Reset

alerting/provider/awsses/awsses.go

@@ -0,0 +1,228 @@
+package awsses
+
+import (
+	"errors"
+	"fmt"
+	"strings"
+
+	"github.com/TwiN/gatus/v5/alerting/alert"
+	"github.com/TwiN/gatus/v5/config/endpoint"
+	"github.com/TwiN/logr"
+	"github.com/aws/aws-sdk-go/aws"
+	"github.com/aws/aws-sdk-go/aws/awserr"
+	"github.com/aws/aws-sdk-go/aws/credentials"
+	"github.com/aws/aws-sdk-go/aws/session"
+	"github.com/aws/aws-sdk-go/service/ses"
+	"gopkg.in/yaml.v3"
+)
+
+const (
+	CharSet = "UTF-8"
+)
+
+var (
+	ErrDuplicateGroupOverride = errors.New("duplicate group override")
+	ErrMissingFromOrToFields  = errors.New("from and to fields are required")
+	ErrInvalidAWSAuthConfig   = errors.New("either both or neither of access-key-id and secret-access-key must be specified")
+)
+
+type Config struct {
+	AccessKeyID     string `yaml:"access-key-id"`
+	SecretAccessKey string `yaml:"secret-access-key"`
+	Region          string `yaml:"region"`
+
+	From string `yaml:"from"`
+	To   string `yaml:"to"`
+}
+
+func (cfg *Config) Validate() error {
+	if len(cfg.From) == 0 || len(cfg.To) == 0 {
+		return ErrMissingFromOrToFields
+	}
+	if !((len(cfg.AccessKeyID) == 0 && len(cfg.SecretAccessKey) == 0) || (len(cfg.AccessKeyID) > 0 && len(cfg.SecretAccessKey) > 0)) {
+		// if both AccessKeyID and SecretAccessKey are specified, we'll use these to authenticate,
+		// otherwise if neither are specified, then we'll fall back on IAM authentication.
+		return ErrInvalidAWSAuthConfig
+	}
+	return nil
+}
+
+func (cfg *Config) Merge(override *Config) {
+	if len(override.AccessKeyID) > 0 {
+		cfg.AccessKeyID = override.AccessKeyID
+	}
+	if len(override.SecretAccessKey) > 0 {
+		cfg.SecretAccessKey = override.SecretAccessKey
+	}
+	if len(override.Region) > 0 {
+		cfg.Region = override.Region
+	}
+	if len(override.From) > 0 {
+		cfg.From = override.From
+	}
+	if len(override.To) > 0 {
+		cfg.To = override.To
+	}
+}
+
+// AlertProvider is the configuration necessary for sending an alert using AWS Simple Email Service
+type AlertProvider struct {
+	DefaultConfig Config `yaml:",inline"`
+
+	// DefaultAlert is the default alert configuration to use for endpoints with an alert of the appropriate type
+	DefaultAlert *alert.Alert `yaml:"default-alert,omitempty"`
+
+	// Overrides is a list of Override that may be prioritized over the default configuration
+	Overrides []Override `yaml:"overrides,omitempty"`
+}
+
+// Override is a case under which the default integration is overridden
+type Override struct {
+	Group  string `yaml:"group"`
+	Config `yaml:",inline"`
+}
+
+// Validate the provider's configuration
+func (provider *AlertProvider) Validate() error {
+	registeredGroups := make(map[string]bool)
+	if provider.Overrides != nil {
+		for _, override := range provider.Overrides {
+			if isAlreadyRegistered := registeredGroups[override.Group]; isAlreadyRegistered || override.Group == "" || len(override.To) == 0 {
+				return ErrDuplicateGroupOverride
+			}
+			registeredGroups[override.Group] = true
+		}
+	}
+	return provider.DefaultConfig.Validate()
+}
+
+// Send an alert using the provider
+func (provider *AlertProvider) Send(ep *endpoint.Endpoint, alert *alert.Alert, result *endpoint.Result, resolved bool) error {
+	cfg, err := provider.GetConfig(ep.Group, alert)
+	if err != nil {
+		return err
+	}
+	awsSession, err := provider.createSession(cfg)
+	if err != nil {
+		return err
+	}
+	svc := ses.New(awsSession)
+	subject, body := provider.buildMessageSubjectAndBody(ep, alert, result, resolved)
+	emails := strings.Split(cfg.To, ",")
+
+	input := &ses.SendEmailInput{
+		Destination: &ses.Destination{
+			ToAddresses: aws.StringSlice(emails),
+		},
+		Message: &ses.Message{
+			Body: &ses.Body{
+				Text: &ses.Content{
+					Charset: aws.String(CharSet),
+					Data:    aws.String(body),
+				},
+			},
+			Subject: &ses.Content{
+				Charset: aws.String(CharSet),
+				Data:    aws.String(subject),
+			},
+		},
+		Source: aws.String(cfg.From),
+	}
+	if _, err = svc.SendEmail(input); err != nil {
+		if aerr, ok := err.(awserr.Error); ok {
+			switch aerr.Code() {
+			case ses.ErrCodeMessageRejected:
+				logr.Error(ses.ErrCodeMessageRejected + ": " + aerr.Error())
+			case ses.ErrCodeMailFromDomainNotVerifiedException:
+				logr.Error(ses.ErrCodeMailFromDomainNotVerifiedException + ": " + aerr.Error())
+			case ses.ErrCodeConfigurationSetDoesNotExistException:
+				logr.Error(ses.ErrCodeConfigurationSetDoesNotExistException + ": " + aerr.Error())
+			default:
+				logr.Error(aerr.Error())
+			}
+		} else {
+			// Print the error, cast err to awserr.Error to get the Code and
+			// Message from an error.
+			logr.Error(err.Error())
+		}
+
+		return err
+	}
+	return nil
+}
+
+func (provider *AlertProvider) createSession(cfg *Config) (*session.Session, error) {
+	awsConfig := &aws.Config{
+		Region: aws.String(cfg.Region),
+	}
+	if len(cfg.AccessKeyID) > 0 && len(cfg.SecretAccessKey) > 0 {
+		awsConfig.Credentials = credentials.NewStaticCredentials(cfg.AccessKeyID, cfg.SecretAccessKey, "")
+	}
+	return session.NewSession(awsConfig)
+}
+
+// buildMessageSubjectAndBody builds the message subject and body
+func (provider *AlertProvider) buildMessageSubjectAndBody(ep *endpoint.Endpoint, alert *alert.Alert, result *endpoint.Result, resolved bool) (string, string) {
+	var subject, message string
+	if resolved {
+		subject = fmt.Sprintf("[%s] Alert resolved", ep.DisplayName())
+		message = fmt.Sprintf("An alert for %s has been resolved after passing successfully %d time(s) in a row", ep.DisplayName(), alert.SuccessThreshold)
+	} else {
+		subject = fmt.Sprintf("[%s] Alert triggered", ep.DisplayName())
+		message = fmt.Sprintf("An alert for %s has been triggered due to having failed %d time(s) in a row", ep.DisplayName(), alert.FailureThreshold)
+	}
+	var formattedConditionResults string
+	if len(result.ConditionResults) > 0 {
+		formattedConditionResults = "\n\nCondition results:\n"
+		for _, conditionResult := range result.ConditionResults {
+			var prefix string
+			if conditionResult.Success {
+				prefix = "✅"
+			} else {
+				prefix = "❌"
+			}
+			formattedConditionResults += fmt.Sprintf("%s %s\n", prefix, conditionResult.Condition)
+		}
+	}
+	var description string
+	if alertDescription := alert.GetDescription(); len(alertDescription) > 0 {
+		description = "\n\nAlert description: " + alertDescription
+	}
+	return subject, message + description + formattedConditionResults
+}
+
+// GetDefaultAlert returns the provider's default alert configuration
+func (provider *AlertProvider) GetDefaultAlert() *alert.Alert {
+	return provider.DefaultAlert
+}
+
+// GetConfig returns the configuration for the provider with the overrides applied
+func (provider *AlertProvider) GetConfig(group string, alert *alert.Alert) (*Config, error) {
+	cfg := provider.DefaultConfig
+	// Handle group overrides
+	if provider.Overrides != nil {
+		for _, override := range provider.Overrides {
+			if group == override.Group {
+				cfg.Merge(&override.Config)
+				break
+			}
+		}
+	}
+	// Handle alert overrides
+	if len(alert.ProviderOverride) != 0 {
+		overrideConfig := Config{}
+		if err := yaml.Unmarshal(alert.ProviderOverrideAsBytes(), &overrideConfig); err != nil {
+			return nil, err
+		}
+		cfg.Merge(&overrideConfig)
+	}
+	// Validate the configuration
+	err := cfg.Validate()
+	return &cfg, err
+}
+
+// ValidateOverrides validates the alert's provider override and, if present, the group override
+func (provider *AlertProvider) ValidateOverrides(group string, alert *alert.Alert) error {
+	_, err := provider.GetConfig(group, alert)
+	return err
+}

alerting/provider/awsses/awsses_test.go

@@ -0,0 +1,250 @@
+package awsses
+
+import (
+	"testing"
+
+	"github.com/TwiN/gatus/v5/alerting/alert"
+	"github.com/TwiN/gatus/v5/config/endpoint"
+)
+
+func TestAlertProvider_Validate(t *testing.T) {
+	invalidProvider := AlertProvider{}
+	if err := invalidProvider.Validate(); err == nil {
+		t.Error("provider shouldn't have been valid")
+	}
+	invalidProviderWithOneKey := AlertProvider{DefaultConfig: Config{From: "from@example.com", To: "to@example.com", AccessKeyID: "1"}}
+	if err := invalidProviderWithOneKey.Validate(); err == nil {
+		t.Error("provider shouldn't have been valid")
+	}
+	validProvider := AlertProvider{DefaultConfig: Config{From: "from@example.com", To: "to@example.com"}}
+	if err := validProvider.Validate(); err != nil {
+		t.Error("provider should've been valid")
+	}
+	validProviderWithKeys := AlertProvider{DefaultConfig: Config{From: "from@example.com", To: "to@example.com", AccessKeyID: "1", SecretAccessKey: "1"}}
+	if err := validProviderWithKeys.Validate(); err != nil {
+		t.Error("provider should've been valid")
+	}
+}
+
+func TestAlertProvider_ValidateWithOverride(t *testing.T) {
+	providerWithInvalidOverrideGroup := AlertProvider{
+		Overrides: []Override{
+			{
+				Config: Config{To: "to@example.com"},
+				Group:  "",
+			},
+		},
+	}
+	if err := providerWithInvalidOverrideGroup.Validate(); err == nil {
+		t.Error("provider Group shouldn't have been valid")
+	}
+	providerWithInvalidOverrideTo := AlertProvider{
+		Overrides: []Override{
+			{
+				Config: Config{To: ""},
+				Group:  "group",
+			},
+		},
+	}
+	if err := providerWithInvalidOverrideTo.Validate(); err == nil {
+		t.Error("provider integration key shouldn't have been valid")
+	}
+	providerWithValidOverride := AlertProvider{
+		DefaultConfig: Config{
+			From: "from@example.com",
+			To:   "to@example.com",
+		},
+		Overrides: []Override{
+			{
+				Config: Config{To: "to@example.com"},
+				Group:  "group",
+			},
+		},
+	}
+	if err := providerWithValidOverride.Validate(); err != nil {
+		t.Error("provider should've been valid")
+	}
+}
+
+func TestAlertProvider_buildRequestBody(t *testing.T) {
+	firstDescription := "description-1"
+	secondDescription := "description-2"
+	scenarios := []struct {
+		Name            string
+		Provider        AlertProvider
+		Alert           alert.Alert
+		Resolved        bool
+		ExpectedSubject string
+		ExpectedBody    string
+	}{
+		{
+			Name:            "triggered",
+			Provider:        AlertProvider{},
+			Alert:           alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:        false,
+			ExpectedSubject: "[endpoint-name] Alert triggered",
+			ExpectedBody:    "An alert for endpoint-name has been triggered due to having failed 3 time(s) in a row\n\nAlert description: description-1\n\nCondition results:\n❌ [CONNECTED] == true\n❌ [STATUS] == 200\n",
+		},
+		{
+			Name:            "resolved",
+			Provider:        AlertProvider{},
+			Alert:           alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:        true,
+			ExpectedSubject: "[endpoint-name] Alert resolved",
+			ExpectedBody:    "An alert for endpoint-name has been resolved after passing successfully 5 time(s) in a row\n\nAlert description: description-2\n\nCondition results:\n✅ [CONNECTED] == true\n✅ [STATUS] == 200\n",
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			subject, body := scenario.Provider.buildMessageSubjectAndBody(
+				&endpoint.Endpoint{Name: "endpoint-name"},
+				&scenario.Alert,
+				&endpoint.Result{
+					ConditionResults: []*endpoint.ConditionResult{
+						{Condition: "[CONNECTED] == true", Success: scenario.Resolved},
+						{Condition: "[STATUS] == 200", Success: scenario.Resolved},
+					},
+				},
+				scenario.Resolved,
+			)
+			if subject != scenario.ExpectedSubject {
+				t.Errorf("expected subject to be %s, got %s", scenario.ExpectedSubject, subject)
+			}
+			if body != scenario.ExpectedBody {
+				t.Errorf("expected body to be %s, got %s", scenario.ExpectedBody, body)
+			}
+		})
+	}
+}
+
+func TestAlertProvider_GetDefaultAlert(t *testing.T) {
+	if (&AlertProvider{DefaultAlert: &alert.Alert{}}).GetDefaultAlert() == nil {
+		t.Error("expected default alert to be not nil")
+	}
+	if (&AlertProvider{DefaultAlert: nil}).GetDefaultAlert() != nil {
+		t.Error("expected default alert to be nil")
+	}
+}
+
+func TestAlertProvider_getConfigWithOverrides(t *testing.T) {
+	scenarios := []struct {
+		Name           string
+		Provider       AlertProvider
+		InputGroup     string
+		InputAlert     alert.Alert
+		ExpectedOutput Config
+	}{
+		{
+			Name: "provider-no-override-specify-no-group-should-default",
+			Provider: AlertProvider{
+				DefaultConfig: Config{
+					From: "from@example.com",
+					To:   "to@example.com",
+				},
+				Overrides: nil,
+			},
+			InputGroup:     "",
+			InputAlert:     alert.Alert{},
+			ExpectedOutput: Config{From: "from@example.com", To: "to@example.com"},
+		},
+		{
+			Name: "provider-no-override-specify-group-should-default",
+			Provider: AlertProvider{
+				DefaultConfig: Config{
+					From: "from@example.com",
+					To:   "to@example.com",
+				},
+				Overrides: nil,
+			},
+			InputGroup:     "group",
+			InputAlert:     alert.Alert{},
+			ExpectedOutput: Config{From: "from@example.com", To: "to@example.com"},
+		},
+		{
+			Name: "provider-with-override-specify-no-group-should-default",
+			Provider: AlertProvider{
+				DefaultConfig: Config{
+					From: "from@example.com",
+					To:   "to@example.com",
+				},
+				Overrides: []Override{
+					{
+						Group:  "group",
+						Config: Config{To: "groupto@example.com"},
+					},
+				},
+			},
+			InputGroup:     "",
+			InputAlert:     alert.Alert{},
+			ExpectedOutput: Config{From: "from@example.com", To: "to@example.com"},
+		},
+		{
+			Name: "provider-with-override-specify-group-should-override",
+			Provider: AlertProvider{
+				DefaultConfig: Config{
+					From: "from@example.com",
+					To:   "to@example.com",
+				},
+				Overrides: []Override{
+					{
+						Group:  "group",
+						Config: Config{To: "groupto@example.com", SecretAccessKey: "wow", AccessKeyID: "noway"},
+					},
+				},
+			},
+			InputGroup:     "group",
+			InputAlert:     alert.Alert{},
+			ExpectedOutput: Config{From: "from@example.com", To: "groupto@example.com", SecretAccessKey: "wow", AccessKeyID: "noway"},
+		},
+		{
+			Name: "provider-with-override-specify-group-but-alert-override-should-override-group-override",
+			Provider: AlertProvider{
+				DefaultConfig: Config{
+					From: "from@example.com",
+					To:   "to@example.com",
+				},
+				Overrides: []Override{
+					{
+						Group:  "group",
+						Config: Config{From: "from@example.com", To: "groupto@example.com", SecretAccessKey: "sekrit"},
+					},
+				},
+			},
+			InputGroup: "group",
+			InputAlert: alert.Alert{
+				ProviderOverride: map[string]any{
+					"to":            "alertto@example.com",
+					"access-key-id": 123,
+				},
+			},
+			ExpectedOutput: Config{To: "alertto@example.com", From: "from@example.com", AccessKeyID: "123", SecretAccessKey: "sekrit"},
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			got, err := scenario.Provider.GetConfig(scenario.InputGroup, &scenario.InputAlert)
+			if err != nil {
+				t.Fatalf("unexpected error: %s", err)
+			}
+			if got.From != scenario.ExpectedOutput.From {
+				t.Errorf("expected From to be %s, got %s", scenario.ExpectedOutput.From, got.From)
+			}
+			if got.To != scenario.ExpectedOutput.To {
+				t.Errorf("expected To to be %s, got %s", scenario.ExpectedOutput.To, got.To)
+			}
+			if got.AccessKeyID != scenario.ExpectedOutput.AccessKeyID {
+				t.Errorf("expected AccessKeyID to be %s, got %s", scenario.ExpectedOutput.AccessKeyID, got.AccessKeyID)
+			}
+			if got.SecretAccessKey != scenario.ExpectedOutput.SecretAccessKey {
+				t.Errorf("expected SecretAccessKey to be %s, got %s", scenario.ExpectedOutput.SecretAccessKey, got.SecretAccessKey)
+			}
+			if got.Region != scenario.ExpectedOutput.Region {
+				t.Errorf("expected Region to be %s, got %s", scenario.ExpectedOutput.Region, got.Region)
+			}
+			// Test ValidateOverrides as well, since it really just calls GetConfig
+			if err = scenario.Provider.ValidateOverrides(scenario.InputGroup, &scenario.InputAlert); err != nil {
+				t.Errorf("unexpected error: %s", err)
+			}
+		})
+	}
+}

alerting/provider/custom/custom.go

@@ -0,0 +1,179 @@
+package custom
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+	"strings"
+
+	"github.com/TwiN/gatus/v5/alerting/alert"
+	"github.com/TwiN/gatus/v5/client"
+	"github.com/TwiN/gatus/v5/config/endpoint"
+	"gopkg.in/yaml.v3"
+)
+
+var (
+	ErrURLNotSet = errors.New("url not set")
+)
+
+type Config struct {
+	URL          string                       `yaml:"url"`
+	Method       string                       `yaml:"method,omitempty"`
+	Body         string                       `yaml:"body,omitempty"`
+	Headers      map[string]string            `yaml:"headers,omitempty"`
+	Placeholders map[string]map[string]string `yaml:"placeholders,omitempty"`
+
+	// ClientConfig is the configuration of the client used to communicate with the provider's target
+	ClientConfig *client.Config `yaml:"client,omitempty"`
+}
+
+func (cfg *Config) Validate() error {
+	if len(cfg.URL) == 0 {
+		return ErrURLNotSet
+	}
+	return nil
+}
+
+func (cfg *Config) Merge(override *Config) {
+	if override.ClientConfig != nil {
+		cfg.ClientConfig = override.ClientConfig
+	}
+	if len(override.URL) > 0 {
+		cfg.URL = override.URL
+	}
+	if len(override.Method) > 0 {
+		cfg.Method = override.Method
+	}
+	if len(override.Body) > 0 {
+		cfg.Body = override.Body
+	}
+	if len(override.Headers) > 0 {
+		cfg.Headers = override.Headers
+	}
+	if len(override.Placeholders) > 0 {
+		cfg.Placeholders = override.Placeholders
+	}
+}
+
+// AlertProvider is the configuration necessary for sending an alert using a custom HTTP request
+// Technically, all alert providers should be reachable using the custom alert provider
+type AlertProvider struct {
+	DefaultConfig Config `yaml:",inline"`
+
+	// DefaultAlert is the default alert configuration to use for endpoints with an alert of the appropriate type
+	DefaultAlert *alert.Alert `yaml:"default-alert,omitempty"`
+
+	// Overrides is a list of Override that may be prioritized over the default configuration
+	Overrides []Override `yaml:"overrides,omitempty"`
+}
+
+// Override is a case under which the default integration is overridden
+type Override struct {
+	Group  string `yaml:"group"`
+	Config `yaml:",inline"`
+}
+
+// Validate the provider's configuration
+func (provider *AlertProvider) Validate() error {
+	return provider.DefaultConfig.Validate()
+}
+
+func (provider *AlertProvider) Send(ep *endpoint.Endpoint, alert *alert.Alert, result *endpoint.Result, resolved bool) error {
+	cfg, err := provider.GetConfig(ep.Group, alert)
+	if err != nil {
+		return err
+	}
+	request := provider.buildHTTPRequest(cfg, ep, alert, result, resolved)
+	response, err := client.GetHTTPClient(cfg.ClientConfig).Do(request)
+	if err != nil {
+		return err
+	}
+	defer response.Body.Close()
+	if response.StatusCode > 399 {
+		body, _ := io.ReadAll(response.Body)
+		return fmt.Errorf("call to provider alert returned status code %d: %s", response.StatusCode, string(body))
+	}
+	return err
+}
+
+func (provider *AlertProvider) buildHTTPRequest(cfg *Config, ep *endpoint.Endpoint, alert *alert.Alert, result *endpoint.Result, resolved bool) *http.Request {
+	body, url, method := cfg.Body, cfg.URL, cfg.Method
+	body = strings.ReplaceAll(body, "[ALERT_DESCRIPTION]", alert.GetDescription())
+	url = strings.ReplaceAll(url, "[ALERT_DESCRIPTION]", alert.GetDescription())
+	body = strings.ReplaceAll(body, "[ENDPOINT_NAME]", ep.Name)
+	url = strings.ReplaceAll(url, "[ENDPOINT_NAME]", ep.Name)
+	body = strings.ReplaceAll(body, "[ENDPOINT_GROUP]", ep.Group)
+	url = strings.ReplaceAll(url, "[ENDPOINT_GROUP]", ep.Group)
+	body = strings.ReplaceAll(body, "[ENDPOINT_URL]", ep.URL)
+	url = strings.ReplaceAll(url, "[ENDPOINT_URL]", ep.URL)
+	body = strings.ReplaceAll(body, "[RESULT_ERRORS]", strings.Join(result.Errors, ","))
+	url = strings.ReplaceAll(url, "[RESULT_ERRORS]", strings.Join(result.Errors, ","))
+	if resolved {
+		body = strings.ReplaceAll(body, "[ALERT_TRIGGERED_OR_RESOLVED]", provider.GetAlertStatePlaceholderValue(cfg, true))
+		url = strings.ReplaceAll(url, "[ALERT_TRIGGERED_OR_RESOLVED]", provider.GetAlertStatePlaceholderValue(cfg, true))
+	} else {
+		body = strings.ReplaceAll(body, "[ALERT_TRIGGERED_OR_RESOLVED]", provider.GetAlertStatePlaceholderValue(cfg, false))
+		url = strings.ReplaceAll(url, "[ALERT_TRIGGERED_OR_RESOLVED]", provider.GetAlertStatePlaceholderValue(cfg, false))
+	}
+	if len(method) == 0 {
+		method = http.MethodGet
+	}
+	bodyBuffer := bytes.NewBuffer([]byte(body))
+	request, _ := http.NewRequest(method, url, bodyBuffer)
+	for k, v := range cfg.Headers {
+		request.Header.Set(k, v)
+	}
+	return request
+}
+
+// GetAlertStatePlaceholderValue returns the Placeholder value for ALERT_TRIGGERED_OR_RESOLVED if configured
+func (provider *AlertProvider) GetAlertStatePlaceholderValue(cfg *Config, resolved bool) string {
+	status := "TRIGGERED"
+	if resolved {
+		status = "RESOLVED"
+	}
+	if _, ok := cfg.Placeholders["ALERT_TRIGGERED_OR_RESOLVED"]; ok {
+		if val, ok := cfg.Placeholders["ALERT_TRIGGERED_OR_RESOLVED"][status]; ok {
+			return val
+		}
+	}
+	return status
+}
+
+// GetDefaultAlert returns the provider's default alert configuration
+func (provider *AlertProvider) GetDefaultAlert() *alert.Alert {
+	return provider.DefaultAlert
+}
+
+// GetConfig returns the configuration for the provider with the overrides applied
+func (provider *AlertProvider) GetConfig(group string, alert *alert.Alert) (*Config, error) {
+	cfg := provider.DefaultConfig
+	// Handle group overrides
+	if provider.Overrides != nil {
+		for _, override := range provider.Overrides {
+			if group == override.Group {
+				cfg.Merge(&override.Config)
+				break
+			}
+		}
+	}
+	// Handle alert overrides
+	if len(alert.ProviderOverride) != 0 {
+		overrideConfig := Config{}
+		if err := yaml.Unmarshal(alert.ProviderOverrideAsBytes(), &overrideConfig); err != nil {
+			return nil, err
+		}
+		cfg.Merge(&overrideConfig)
+	}
+	// Validate the configuration
+	err := cfg.Validate()
+	return &cfg, err
+}
+
+// ValidateOverrides validates the alert's provider override and, if present, the group override
+func (provider *AlertProvider) ValidateOverrides(group string, alert *alert.Alert) error {
+	_, err := provider.GetConfig(group, alert)
+	return err
+}

alerting/provider/custom/custom_test.go

@@ -0,0 +1,395 @@
+package custom
+
+import (
+	"fmt"
+	"io"
+	"net/http"
+	"testing"
+
+	"github.com/TwiN/gatus/v5/alerting/alert"
+	"github.com/TwiN/gatus/v5/client"
+	"github.com/TwiN/gatus/v5/config/endpoint"
+	"github.com/TwiN/gatus/v5/test"
+)
+
+func TestAlertProvider_Validate(t *testing.T) {
+	t.Run("invalid-provider", func(t *testing.T) {
+		invalidProvider := AlertProvider{DefaultConfig: Config{URL: ""}}
+		if err := invalidProvider.Validate(); err == nil {
+			t.Error("provider shouldn't have been valid")
+		}
+	})
+	t.Run("valid-provider", func(t *testing.T) {
+		validProvider := AlertProvider{DefaultConfig: Config{URL: "https://example.com"}}
+		if err := validProvider.Validate(); err != nil {
+			t.Error("provider should've been valid")
+		}
+	})
+}
+
+func TestAlertProvider_Send(t *testing.T) {
+	defer client.InjectHTTPClient(nil)
+	firstDescription := "description-1"
+	secondDescription := "description-2"
+	scenarios := []struct {
+		Name             string
+		Provider         AlertProvider
+		Alert            alert.Alert
+		Resolved         bool
+		MockRoundTripper test.MockRoundTripper
+		ExpectedError    bool
+	}{
+		{
+			Name:     "triggered",
+			Provider: AlertProvider{DefaultConfig: Config{URL: "https://example.com"}},
+			Alert:    alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: false,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusOK, Body: http.NoBody}
+			}),
+			ExpectedError: false,
+		},
+		{
+			Name:     "triggered-error",
+			Provider: AlertProvider{DefaultConfig: Config{URL: "https://example.com"}},
+			Alert:    alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: false,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusInternalServerError, Body: http.NoBody}
+			}),
+			ExpectedError: true,
+		},
+		{
+			Name:     "resolved",
+			Provider: AlertProvider{DefaultConfig: Config{URL: "https://example.com"}},
+			Alert:    alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: true,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusOK, Body: http.NoBody}
+			}),
+			ExpectedError: false,
+		},
+		{
+			Name:     "resolved-error",
+			Provider: AlertProvider{DefaultConfig: Config{URL: "https://example.com"}},
+			Alert:    alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: true,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusInternalServerError, Body: http.NoBody}
+			}),
+			ExpectedError: true,
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			client.InjectHTTPClient(&http.Client{Transport: scenario.MockRoundTripper})
+			err := scenario.Provider.Send(
+				&endpoint.Endpoint{Name: "endpoint-name"},
+				&scenario.Alert,
+				&endpoint.Result{
+					ConditionResults: []*endpoint.ConditionResult{
+						{Condition: "[CONNECTED] == true", Success: scenario.Resolved},
+						{Condition: "[STATUS] == 200", Success: scenario.Resolved},
+					},
+				},
+				scenario.Resolved,
+			)
+			if scenario.ExpectedError && err == nil {
+				t.Error("expected error, got none")
+			}
+			if !scenario.ExpectedError && err != nil {
+				t.Error("expected no error, got", err.Error())
+			}
+		})
+	}
+}
+
+func TestAlertProvider_buildHTTPRequest(t *testing.T) {
+	alertProvider := &AlertProvider{
+		DefaultConfig: Config{
+			URL:  "https://example.com/[ENDPOINT_GROUP]/[ENDPOINT_NAME]?event=[ALERT_TRIGGERED_OR_RESOLVED]&description=[ALERT_DESCRIPTION]&url=[ENDPOINT_URL]",
+			Body: "[ENDPOINT_NAME],[ENDPOINT_GROUP],[ALERT_DESCRIPTION],[ENDPOINT_URL],[ALERT_TRIGGERED_OR_RESOLVED]",
+		},
+	}
+	alertDescription := "alert-description"
+	scenarios := []struct {
+		AlertProvider *AlertProvider
+		Resolved      bool
+		ExpectedURL   string
+		ExpectedBody  string
+	}{
+		{
+			AlertProvider: alertProvider,
+			Resolved:      true,
+			ExpectedURL:   "https://example.com/endpoint-group/endpoint-name?event=RESOLVED&description=alert-description&url=https://example.com",
+			ExpectedBody:  "endpoint-name,endpoint-group,alert-description,https://example.com,RESOLVED",
+		},
+		{
+			AlertProvider: alertProvider,
+			Resolved:      false,
+			ExpectedURL:   "https://example.com/endpoint-group/endpoint-name?event=TRIGGERED&description=alert-description&url=https://example.com",
+			ExpectedBody:  "endpoint-name,endpoint-group,alert-description,https://example.com,TRIGGERED",
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(fmt.Sprintf("resolved-%v-with-default-placeholders", scenario.Resolved), func(t *testing.T) {
+			request := alertProvider.buildHTTPRequest(
+				&alertProvider.DefaultConfig,
+				&endpoint.Endpoint{Name: "endpoint-name", Group: "endpoint-group", URL: "https://example.com"},
+				&alert.Alert{Description: &alertDescription},
+				&endpoint.Result{Errors: []string{}},
+				scenario.Resolved,
+			)
+			if request.URL.String() != scenario.ExpectedURL {
+				t.Error("expected URL to be", scenario.ExpectedURL, "got", request.URL.String())
+			}
+			body, _ := io.ReadAll(request.Body)
+			if string(body) != scenario.ExpectedBody {
+				t.Error("expected body to be", scenario.ExpectedBody, "got", string(body))
+			}
+		})
+	}
+}
+
+func TestAlertProviderWithResultErrors_buildHTTPRequest(t *testing.T) {
+	alertProvider := &AlertProvider{
+		DefaultConfig: Config{
+			URL:  "https://example.com/[ENDPOINT_GROUP]/[ENDPOINT_NAME]?event=[ALERT_TRIGGERED_OR_RESOLVED]&description=[ALERT_DESCRIPTION]&url=[ENDPOINT_URL]&error=[RESULT_ERRORS]",
+			Body: "[ENDPOINT_NAME],[ENDPOINT_GROUP],[ALERT_DESCRIPTION],[ENDPOINT_URL],[ALERT_TRIGGERED_OR_RESOLVED],[RESULT_ERRORS]",
+		},
+	}
+	alertDescription := "alert-description"
+	scenarios := []struct {
+		AlertProvider *AlertProvider
+		Resolved      bool
+		ExpectedURL   string
+		ExpectedBody  string
+		Errors        []string
+	}{
+		{
+			AlertProvider: alertProvider,
+			Resolved:      true,
+			ExpectedURL:   "https://example.com/endpoint-group/endpoint-name?event=RESOLVED&description=alert-description&url=https://example.com&error=",
+			ExpectedBody:  "endpoint-name,endpoint-group,alert-description,https://example.com,RESOLVED,",
+		},
+		{
+			AlertProvider: alertProvider,
+			Resolved:      false,
+			ExpectedURL:   "https://example.com/endpoint-group/endpoint-name?event=TRIGGERED&description=alert-description&url=https://example.com&error=error1,error2",
+			ExpectedBody:  "endpoint-name,endpoint-group,alert-description,https://example.com,TRIGGERED,error1,error2",
+			Errors:        []string{"error1", "error2"},
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(fmt.Sprintf("resolved-%v-with-default-placeholders-and-result-errors", scenario.Resolved), func(t *testing.T) {
+			request := alertProvider.buildHTTPRequest(
+				&alertProvider.DefaultConfig,
+				&endpoint.Endpoint{Name: "endpoint-name", Group: "endpoint-group", URL: "https://example.com"},
+				&alert.Alert{Description: &alertDescription},
+				&endpoint.Result{Errors: scenario.Errors},
+				scenario.Resolved,
+			)
+			if request.URL.String() != scenario.ExpectedURL {
+				t.Error("expected URL to be", scenario.ExpectedURL, "got", request.URL.String())
+			}
+			body, _ := io.ReadAll(request.Body)
+			if string(body) != scenario.ExpectedBody {
+				t.Error("expected body to be", scenario.ExpectedBody, "got", string(body))
+			}
+		})
+	}
+}
+
+func TestAlertProvider_buildHTTPRequestWithCustomPlaceholder(t *testing.T) {
+	alertProvider := &AlertProvider{
+		DefaultConfig: Config{
+			URL:     "https://example.com/[ENDPOINT_GROUP]/[ENDPOINT_NAME]?event=[ALERT_TRIGGERED_OR_RESOLVED]&description=[ALERT_DESCRIPTION]",
+			Body:    "[ENDPOINT_NAME],[ENDPOINT_GROUP],[ALERT_DESCRIPTION],[ALERT_TRIGGERED_OR_RESOLVED]",
+			Headers: nil,
+			Placeholders: map[string]map[string]string{
+				"ALERT_TRIGGERED_OR_RESOLVED": {
+					"RESOLVED":  "fixed",
+					"TRIGGERED": "boom",
+				},
+			},
+		},
+	}
+	alertDescription := "alert-description"
+	scenarios := []struct {
+		AlertProvider *AlertProvider
+		Resolved      bool
+		ExpectedURL   string
+		ExpectedBody  string
+	}{
+		{
+			AlertProvider: alertProvider,
+			Resolved:      true,
+			ExpectedURL:   "https://example.com/endpoint-group/endpoint-name?event=fixed&description=alert-description",
+			ExpectedBody:  "endpoint-name,endpoint-group,alert-description,fixed",
+		},
+		{
+			AlertProvider: alertProvider,
+			Resolved:      false,
+			ExpectedURL:   "https://example.com/endpoint-group/endpoint-name?event=boom&description=alert-description",
+			ExpectedBody:  "endpoint-name,endpoint-group,alert-description,boom",
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(fmt.Sprintf("resolved-%v-with-custom-placeholders", scenario.Resolved), func(t *testing.T) {
+			request := alertProvider.buildHTTPRequest(
+				&alertProvider.DefaultConfig,
+				&endpoint.Endpoint{Name: "endpoint-name", Group: "endpoint-group"},
+				&alert.Alert{Description: &alertDescription},
+				&endpoint.Result{},
+				scenario.Resolved,
+			)
+			if request.URL.String() != scenario.ExpectedURL {
+				t.Error("expected URL to be", scenario.ExpectedURL, "got", request.URL.String())
+			}
+			body, _ := io.ReadAll(request.Body)
+			if string(body) != scenario.ExpectedBody {
+				t.Error("expected body to be", scenario.ExpectedBody, "got", string(body))
+			}
+		})
+	}
+}
+
+func TestAlertProvider_GetAlertStatePlaceholderValueDefaults(t *testing.T) {
+	alertProvider := &AlertProvider{
+		DefaultConfig: Config{
+			URL:  "https://example.com/[ENDPOINT_NAME]?event=[ALERT_TRIGGERED_OR_RESOLVED]&description=[ALERT_DESCRIPTION]",
+			Body: "[ENDPOINT_NAME],[ENDPOINT_GROUP],[ALERT_DESCRIPTION],[ALERT_TRIGGERED_OR_RESOLVED]",
+		},
+	}
+	if alertProvider.GetAlertStatePlaceholderValue(&alertProvider.DefaultConfig, true) != "RESOLVED" {
+		t.Error("expected RESOLVED, got", alertProvider.GetAlertStatePlaceholderValue(&alertProvider.DefaultConfig, true))
+	}
+	if alertProvider.GetAlertStatePlaceholderValue(&alertProvider.DefaultConfig, false) != "TRIGGERED" {
+		t.Error("expected TRIGGERED, got", alertProvider.GetAlertStatePlaceholderValue(&alertProvider.DefaultConfig, false))
+	}
+}
+
+func TestAlertProvider_GetDefaultAlert(t *testing.T) {
+	if (&AlertProvider{DefaultAlert: &alert.Alert{}}).GetDefaultAlert() == nil {
+		t.Error("expected default alert to be not nil")
+	}
+	if (&AlertProvider{DefaultAlert: nil}).GetDefaultAlert() != nil {
+		t.Error("expected default alert to be nil")
+	}
+}
+
+func TestAlertProvider_GetConfig(t *testing.T) {
+	scenarios := []struct {
+		Name           string
+		Provider       AlertProvider
+		InputGroup     string
+		InputAlert     alert.Alert
+		ExpectedOutput Config
+	}{
+		{
+			Name: "provider-no-override-specify-no-group-should-default",
+			Provider: AlertProvider{
+				DefaultConfig: Config{URL: "http://example.com", Body: "default-body"},
+				Overrides:     nil,
+			},
+			InputGroup:     "",
+			InputAlert:     alert.Alert{},
+			ExpectedOutput: Config{URL: "http://example.com", Body: "default-body"},
+		},
+		{
+			Name: "provider-no-override-specify-group-should-default",
+			Provider: AlertProvider{
+				DefaultConfig: Config{URL: "http://example.com"},
+				Overrides:     nil,
+			},
+			InputGroup:     "group",
+			InputAlert:     alert.Alert{},
+			ExpectedOutput: Config{URL: "http://example.com"},
+		},
+		{
+			Name: "provider-with-override-specify-no-group-should-default",
+			Provider: AlertProvider{
+				DefaultConfig: Config{URL: "http://example.com"},
+				Overrides: []Override{
+					{
+						Group:  "group",
+						Config: Config{URL: "http://group-example.com", Headers: map[string]string{"Cache": "true"}},
+					},
+				},
+			},
+			InputGroup:     "",
+			InputAlert:     alert.Alert{},
+			ExpectedOutput: Config{URL: "http://example.com", Headers: map[string]string{"Cache": "true"}},
+		},
+		{
+			Name: "provider-with-override-specify-group-should-override",
+			Provider: AlertProvider{
+				DefaultConfig: Config{URL: "http://example.com", Body: "default-body"},
+				Overrides: []Override{
+					{
+						Group:  "group",
+						Config: Config{URL: "http://group-example.com", Body: "group-body"},
+					},
+				},
+			},
+			InputGroup:     "group",
+			InputAlert:     alert.Alert{},
+			ExpectedOutput: Config{URL: "http://group-example.com", Body: "group-body"},
+		},
+		{
+			Name: "provider-with-group-override-and-alert-override--alert-override-should-take-precedence",
+			Provider: AlertProvider{
+				DefaultConfig: Config{URL: "http://example.com"},
+				Overrides: []Override{
+					{
+						Group:  "group",
+						Config: Config{URL: "http://group-example.com"},
+					},
+				},
+			},
+			InputGroup:     "group",
+			InputAlert:     alert.Alert{ProviderOverride: map[string]any{"url": "http://alert-example.com", "body": "alert-body"}},
+			ExpectedOutput: Config{URL: "http://alert-example.com", Body: "alert-body"},
+		},
+		{
+			Name: "provider-with-partial-overrides",
+			Provider: AlertProvider{
+				DefaultConfig: Config{URL: "http://example.com"},
+				Overrides: []Override{
+					{
+						Group:  "group",
+						Config: Config{Method: "POST"},
+					},
+				},
+			},
+			InputGroup:     "group",
+			InputAlert:     alert.Alert{ProviderOverride: map[string]any{"body": "alert-body"}},
+			ExpectedOutput: Config{URL: "http://example.com", Body: "alert-body", Method: "POST"},
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			got, err := scenario.Provider.GetConfig(scenario.InputGroup, &scenario.InputAlert)
+			if err != nil {
+				t.Fatalf("unexpected error: %s", err)
+			}
+			if got.URL != scenario.ExpectedOutput.URL {
+				t.Errorf("expected webhook URL to be %s, got %s", scenario.ExpectedOutput.URL, got.URL)
+			}
+			if got.Body != scenario.ExpectedOutput.Body {
+				t.Errorf("expected body to be %s, got %s", scenario.ExpectedOutput.Body, got.Body)
+			}
+			if got.Headers != nil {
+				for key, value := range scenario.ExpectedOutput.Headers {
+					if got.Headers[key] != value {
+						t.Errorf("expected header %s to be %s, got %s", key, value, got.Headers[key])
+					}
+				}
+			}
+			// Test ValidateOverrides as well, since it really just calls GetConfig
+			if err = scenario.Provider.ValidateOverrides(scenario.InputGroup, &scenario.InputAlert); err != nil {
+				t.Errorf("unexpected error: %s", err)
+			}
+		})
+	}
+}

alerting/provider/discord/discord.go

@@ -0,0 +1,199 @@
+package discord
+
+import (
+	"bytes"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+
+	"github.com/TwiN/gatus/v5/alerting/alert"
+	"github.com/TwiN/gatus/v5/client"
+	"github.com/TwiN/gatus/v5/config/endpoint"
+	"gopkg.in/yaml.v3"
+)
+
+var (
+	ErrWebhookURLNotSet       = errors.New("webhook-url not set")
+	ErrDuplicateGroupOverride = errors.New("duplicate group override")
+)
+
+type Config struct {
+	WebhookURL string `yaml:"webhook-url"`
+	Title      string `yaml:"title,omitempty"` // Title of the message that will be sent
+}
+
+func (cfg *Config) Validate() error {
+	if len(cfg.WebhookURL) == 0 {
+		return ErrWebhookURLNotSet
+	}
+	return nil
+}
+
+func (cfg *Config) Merge(override *Config) {
+	if len(override.WebhookURL) > 0 {
+		cfg.WebhookURL = override.WebhookURL
+	}
+	if len(override.Title) > 0 {
+		cfg.Title = override.Title
+	}
+}
+
+// AlertProvider is the configuration necessary for sending an alert using Discord
+type AlertProvider struct {
+	DefaultConfig Config `yaml:",inline"`
+
+	// DefaultAlert is the default alert configuration to use for endpoints with an alert of the appropriate type
+	DefaultAlert *alert.Alert `yaml:"default-alert,omitempty"`
+
+	// Overrides is a list of Override that may be prioritized over the default configuration
+	Overrides []Override `yaml:"overrides,omitempty"`
+}
+
+type Override struct {
+	Group  string `yaml:"group"`
+	Config `yaml:",inline"`
+}
+
+// Validate the provider's configuration
+func (provider *AlertProvider) Validate() error {
+	registeredGroups := make(map[string]bool)
+	if provider.Overrides != nil {
+		for _, override := range provider.Overrides {
+			if isAlreadyRegistered := registeredGroups[override.Group]; isAlreadyRegistered || override.Group == "" || len(override.WebhookURL) == 0 {
+				return ErrDuplicateGroupOverride
+			}
+			registeredGroups[override.Group] = true
+		}
+	}
+	return provider.DefaultConfig.Validate()
+}
+
+// Send an alert using the provider
+func (provider *AlertProvider) Send(ep *endpoint.Endpoint, alert *alert.Alert, result *endpoint.Result, resolved bool) error {
+	cfg, err := provider.GetConfig(ep.Group, alert)
+	if err != nil {
+		return err
+	}
+	buffer := bytes.NewBuffer(provider.buildRequestBody(cfg, ep, alert, result, resolved))
+	request, err := http.NewRequest(http.MethodPost, cfg.WebhookURL, buffer)
+	if err != nil {
+		return err
+	}
+	request.Header.Set("Content-Type", "application/json")
+	response, err := client.GetHTTPClient(nil).Do(request)
+	if err != nil {
+		return err
+	}
+	defer response.Body.Close()
+	if response.StatusCode > 399 {
+		body, _ := io.ReadAll(response.Body)
+		return fmt.Errorf("call to provider alert returned status code %d: %s", response.StatusCode, string(body))
+	}
+	return err
+}
+
+type Body struct {
+	Content string  `json:"content"`
+	Embeds  []Embed `json:"embeds"`
+}
+
+type Embed struct {
+	Title       string  `json:"title"`
+	Description string  `json:"description"`
+	Color       int     `json:"color"`
+	Fields      []Field `json:"fields,omitempty"`
+}
+
+type Field struct {
+	Name   string `json:"name"`
+	Value  string `json:"value"`
+	Inline bool   `json:"inline"`
+}
+
+// buildRequestBody builds the request body for the provider
+func (provider *AlertProvider) buildRequestBody(cfg *Config, ep *endpoint.Endpoint, alert *alert.Alert, result *endpoint.Result, resolved bool) []byte {
+	var message string
+	var colorCode int
+	if resolved {
+		message = fmt.Sprintf("An alert for **%s** has been resolved after passing successfully %d time(s) in a row", ep.DisplayName(), alert.SuccessThreshold)
+		colorCode = 3066993
+	} else {
+		message = fmt.Sprintf("An alert for **%s** has been triggered due to having failed %d time(s) in a row", ep.DisplayName(), alert.FailureThreshold)
+		colorCode = 15158332
+	}
+	var formattedConditionResults string
+	for _, conditionResult := range result.ConditionResults {
+		var prefix string
+		if conditionResult.Success {
+			prefix = ":white_check_mark:"
+		} else {
+			prefix = ":x:"
+		}
+		formattedConditionResults += fmt.Sprintf("%s - `%s`\n", prefix, conditionResult.Condition)
+	}
+	var description string
+	if alertDescription := alert.GetDescription(); len(alertDescription) > 0 {
+		description = ":\n> " + alertDescription
+	}
+	title := ":helmet_with_white_cross: Gatus"
+	if cfg.Title != "" {
+		title = cfg.Title
+	}
+	body := Body{
+		Content: "",
+		Embeds: []Embed{
+			{
+				Title:       title,
+				Description: message + description,
+				Color:       colorCode,
+			},
+		},
+	}
+	if len(formattedConditionResults) > 0 {
+		body.Embeds[0].Fields = append(body.Embeds[0].Fields, Field{
+			Name:   "Condition results",
+			Value:  formattedConditionResults,
+			Inline: false,
+		})
+	}
+	bodyAsJSON, _ := json.Marshal(body)
+	return bodyAsJSON
+}
+
+// GetDefaultAlert returns the provider's default alert configuration
+func (provider *AlertProvider) GetDefaultAlert() *alert.Alert {
+	return provider.DefaultAlert
+}
+
+// GetConfig returns the configuration for the provider with the overrides applied
+func (provider *AlertProvider) GetConfig(group string, alert *alert.Alert) (*Config, error) {
+	cfg := provider.DefaultConfig
+	// Handle group overrides
+	if provider.Overrides != nil {
+		for _, override := range provider.Overrides {
+			if group == override.Group {
+				cfg.Merge(&override.Config)
+				break
+			}
+		}
+	}
+	// Handle alert overrides
+	if len(alert.ProviderOverride) != 0 {
+		overrideConfig := Config{}
+		if err := yaml.Unmarshal(alert.ProviderOverrideAsBytes(), &overrideConfig); err != nil {
+			return nil, err
+		}
+		cfg.Merge(&overrideConfig)
+	}
+	// Validate the configuration
+	err := cfg.Validate()
+	return &cfg, err
+}
+
+// ValidateOverrides validates the alert's provider override and, if present, the group override
+func (provider *AlertProvider) ValidateOverrides(group string, alert *alert.Alert) error {
+	_, err := provider.GetConfig(group, alert)
+	return err
+}

alerting/provider/discord/discord_test.go

@@ -0,0 +1,332 @@
+package discord
+
+import (
+	"encoding/json"
+	"net/http"
+	"testing"
+
+	"github.com/TwiN/gatus/v5/alerting/alert"
+	"github.com/TwiN/gatus/v5/client"
+	"github.com/TwiN/gatus/v5/config/endpoint"
+	"github.com/TwiN/gatus/v5/test"
+)
+
+func TestAlertProvider_Validate(t *testing.T) {
+	invalidProvider := AlertProvider{DefaultConfig: Config{WebhookURL: ""}}
+	if err := invalidProvider.Validate(); err == nil {
+		t.Error("provider shouldn't have been valid")
+	}
+	validProvider := AlertProvider{DefaultConfig: Config{WebhookURL: "http://example.com"}}
+	if err := validProvider.Validate(); err != nil {
+		t.Error("provider should've been valid")
+	}
+}
+
+func TestAlertProvider_ValidateWithOverride(t *testing.T) {
+	providerWithInvalidOverrideGroup := AlertProvider{
+		Overrides: []Override{
+			{
+				Config: Config{WebhookURL: "http://example.com"},
+				Group:  "",
+			},
+		},
+	}
+	if err := providerWithInvalidOverrideGroup.Validate(); err == nil {
+		t.Error("provider Group shouldn't have been valid")
+	}
+	providerWithInvalidOverrideTo := AlertProvider{
+		Overrides: []Override{
+			{
+				Config: Config{WebhookURL: ""},
+				Group:  "group",
+			},
+		},
+	}
+	if err := providerWithInvalidOverrideTo.Validate(); err == nil {
+		t.Error("provider integration key shouldn't have been valid")
+	}
+	providerWithValidOverride := AlertProvider{
+		DefaultConfig: Config{
+			WebhookURL: "http://example.com",
+		},
+		Overrides: []Override{
+			{
+				Config: Config{WebhookURL: "http://example.com"},
+				Group:  "group",
+			},
+		},
+	}
+	if err := providerWithValidOverride.Validate(); err != nil {
+		t.Error("provider should've been valid")
+	}
+}
+
+func TestAlertProvider_Send(t *testing.T) {
+	defer client.InjectHTTPClient(nil)
+	firstDescription := "description-1"
+	secondDescription := "description-2"
+	title := "provider-title"
+	scenarios := []struct {
+		Name             string
+		Provider         AlertProvider
+		Alert            alert.Alert
+		Resolved         bool
+		MockRoundTripper test.MockRoundTripper
+		ExpectedError    bool
+	}{
+		{
+			Name:     "triggered",
+			Provider: AlertProvider{DefaultConfig: Config{WebhookURL: "http://example.com"}},
+			Alert:    alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: false,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusOK, Body: http.NoBody}
+			}),
+			ExpectedError: false,
+		},
+		{
+			Name:     "triggered-error",
+			Provider: AlertProvider{DefaultConfig: Config{WebhookURL: "http://example.com"}},
+			Alert:    alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: false,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusInternalServerError, Body: http.NoBody}
+			}),
+			ExpectedError: true,
+		},
+		{
+			Name:     "resolved",
+			Provider: AlertProvider{DefaultConfig: Config{WebhookURL: "http://example.com"}},
+			Alert:    alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: true,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusOK, Body: http.NoBody}
+			}),
+			ExpectedError: false,
+		},
+		{
+			Name:     "resolved-error",
+			Provider: AlertProvider{DefaultConfig: Config{WebhookURL: "http://example.com"}},
+			Alert:    alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: true,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusInternalServerError, Body: http.NoBody}
+			}),
+			ExpectedError: true,
+		},
+		{
+			Name:     "triggered-with-modified-title",
+			Provider: AlertProvider{DefaultConfig: Config{WebhookURL: "http://example.com", Title: title}},
+			Alert:    alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: false,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusOK, Body: http.NoBody}
+			}),
+			ExpectedError: false,
+		},
+		{
+			Name:     "triggered-with-webhook-override",
+			Provider: AlertProvider{DefaultConfig: Config{WebhookURL: "http://example.com"}},
+			Alert:    alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3, ProviderOverride: map[string]any{"webhook-url": "http://example01.com"}},
+			Resolved: false,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusOK, Body: http.NoBody}
+			}),
+			ExpectedError: false,
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			client.InjectHTTPClient(&http.Client{Transport: scenario.MockRoundTripper})
+			err := scenario.Provider.Send(
+				&endpoint.Endpoint{Name: "endpoint-name"},
+				&scenario.Alert,
+				&endpoint.Result{
+					ConditionResults: []*endpoint.ConditionResult{
+						{Condition: "[CONNECTED] == true", Success: scenario.Resolved},
+						{Condition: "[STATUS] == 200", Success: scenario.Resolved},
+					},
+				},
+				scenario.Resolved,
+			)
+			if scenario.ExpectedError && err == nil {
+				t.Error("expected error, got none")
+			}
+			if !scenario.ExpectedError && err != nil {
+				t.Error("expected no error, got", err.Error())
+			}
+		})
+	}
+}
+
+func TestAlertProvider_buildRequestBody(t *testing.T) {
+	firstDescription := "description-1"
+	secondDescription := "description-2"
+	title := "provider-title"
+	scenarios := []struct {
+		Name         string
+		Provider     AlertProvider
+		Alert        alert.Alert
+		NoConditions bool
+		Resolved     bool
+		ExpectedBody string
+	}{
+		{
+			Name:         "triggered",
+			Provider:     AlertProvider{},
+			Alert:        alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     false,
+			ExpectedBody: "{\"content\":\"\",\"embeds\":[{\"title\":\":helmet_with_white_cross: Gatus\",\"description\":\"An alert for **endpoint-name** has been triggered due to having failed 3 time(s) in a row:\\n\\u003e description-1\",\"color\":15158332,\"fields\":[{\"name\":\"Condition results\",\"value\":\":x: - `[CONNECTED] == true`\\n:x: - `[STATUS] == 200`\\n:x: - `[BODY] != \\\"\\\"`\\n\",\"inline\":false}]}]}",
+		},
+		{
+			Name:         "resolved",
+			Provider:     AlertProvider{},
+			Alert:        alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     true,
+			ExpectedBody: "{\"content\":\"\",\"embeds\":[{\"title\":\":helmet_with_white_cross: Gatus\",\"description\":\"An alert for **endpoint-name** has been resolved after passing successfully 5 time(s) in a row:\\n\\u003e description-2\",\"color\":3066993,\"fields\":[{\"name\":\"Condition results\",\"value\":\":white_check_mark: - `[CONNECTED] == true`\\n:white_check_mark: - `[STATUS] == 200`\\n:white_check_mark: - `[BODY] != \\\"\\\"`\\n\",\"inline\":false}]}]}",
+		},
+		{
+			Name:         "triggered-with-modified-title",
+			Provider:     AlertProvider{DefaultConfig: Config{Title: title}},
+			Alert:        alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     false,
+			ExpectedBody: "{\"content\":\"\",\"embeds\":[{\"title\":\"provider-title\",\"description\":\"An alert for **endpoint-name** has been triggered due to having failed 3 time(s) in a row:\\n\\u003e description-1\",\"color\":15158332,\"fields\":[{\"name\":\"Condition results\",\"value\":\":x: - `[CONNECTED] == true`\\n:x: - `[STATUS] == 200`\\n:x: - `[BODY] != \\\"\\\"`\\n\",\"inline\":false}]}]}",
+		},
+		{
+			Name:         "triggered-with-no-conditions",
+			NoConditions: true,
+			Provider:     AlertProvider{DefaultConfig: Config{Title: title}},
+			Alert:        alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     false,
+			ExpectedBody: "{\"content\":\"\",\"embeds\":[{\"title\":\"provider-title\",\"description\":\"An alert for **endpoint-name** has been triggered due to having failed 3 time(s) in a row:\\n\\u003e description-1\",\"color\":15158332}]}",
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			var conditionResults []*endpoint.ConditionResult
+			if !scenario.NoConditions {
+				conditionResults = []*endpoint.ConditionResult{
+					{Condition: "[CONNECTED] == true", Success: scenario.Resolved},
+					{Condition: "[STATUS] == 200", Success: scenario.Resolved},
+					{Condition: "[BODY] != \"\"", Success: scenario.Resolved},
+				}
+			}
+			body := scenario.Provider.buildRequestBody(
+				&scenario.Provider.DefaultConfig,
+				&endpoint.Endpoint{Name: "endpoint-name"},
+				&scenario.Alert,
+				&endpoint.Result{
+					ConditionResults: conditionResults,
+				},
+				scenario.Resolved,
+			)
+			if string(body) != scenario.ExpectedBody {
+				t.Errorf("expected:\n%s\ngot:\n%s", scenario.ExpectedBody, body)
+			}
+			out := make(map[string]interface{})
+			if err := json.Unmarshal(body, &out); err != nil {
+				t.Error("expected body to be valid JSON, got error:", err.Error())
+			}
+		})
+	}
+}
+
+func TestAlertProvider_GetDefaultAlert(t *testing.T) {
+	if (&AlertProvider{DefaultAlert: &alert.Alert{}}).GetDefaultAlert() == nil {
+		t.Error("expected default alert to be not nil")
+	}
+	if (&AlertProvider{DefaultAlert: nil}).GetDefaultAlert() != nil {
+		t.Error("expected default alert to be nil")
+	}
+}
+
+func TestAlertProvider_GetConfig(t *testing.T) {
+	scenarios := []struct {
+		Name           string
+		Provider       AlertProvider
+		InputGroup     string
+		InputAlert     alert.Alert
+		ExpectedOutput Config
+	}{
+		{
+			Name: "provider-no-override-specify-no-group-should-default",
+			Provider: AlertProvider{
+				DefaultConfig: Config{WebhookURL: "http://example.com"},
+				Overrides:     nil,
+			},
+			InputGroup:     "",
+			InputAlert:     alert.Alert{},
+			ExpectedOutput: Config{WebhookURL: "http://example.com"},
+		},
+		{
+			Name: "provider-no-override-specify-group-should-default",
+			Provider: AlertProvider{
+				DefaultConfig: Config{WebhookURL: "http://example.com"},
+				Overrides:     nil,
+			},
+			InputGroup:     "group",
+			InputAlert:     alert.Alert{},
+			ExpectedOutput: Config{WebhookURL: "http://example.com"},
+		},
+		{
+			Name: "provider-with-override-specify-no-group-should-default",
+			Provider: AlertProvider{
+				DefaultConfig: Config{WebhookURL: "http://example.com"},
+				Overrides: []Override{
+					{
+						Group:  "group",
+						Config: Config{WebhookURL: "http://group-example.com"},
+					},
+				},
+			},
+			InputGroup:     "",
+			InputAlert:     alert.Alert{},
+			ExpectedOutput: Config{WebhookURL: "http://example.com"},
+		},
+		{
+			Name: "provider-with-override-specify-group-should-override",
+			Provider: AlertProvider{
+				DefaultConfig: Config{WebhookURL: "http://example.com"},
+				Overrides: []Override{
+					{
+						Group:  "group",
+						Config: Config{WebhookURL: "http://group-example.com"},
+					},
+				},
+			},
+			InputGroup:     "group",
+			InputAlert:     alert.Alert{},
+			ExpectedOutput: Config{WebhookURL: "http://group-example.com"},
+		},
+		{
+			Name: "provider-with-group-override-and-alert-override--alert-override-should-take-precedence",
+			Provider: AlertProvider{
+				DefaultConfig: Config{WebhookURL: "http://example.com"},
+				Overrides: []Override{
+					{
+						Group:  "group",
+						Config: Config{WebhookURL: "http://group-example.com"},
+					},
+				},
+			},
+			InputGroup:     "group",
+			InputAlert:     alert.Alert{ProviderOverride: map[string]any{"webhook-url": "http://alert-example.com"}},
+			ExpectedOutput: Config{WebhookURL: "http://alert-example.com"},
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			got, err := scenario.Provider.GetConfig(scenario.InputGroup, &scenario.InputAlert)
+			if err != nil {
+				t.Fatalf("unexpected error: %s", err)
+			}
+			if got.WebhookURL != scenario.ExpectedOutput.WebhookURL {
+				t.Errorf("expected webhook URL to be %s, got %s", scenario.ExpectedOutput.WebhookURL, got.WebhookURL)
+			}
+			// Test ValidateOverrides as well, since it really just calls GetConfig
+			if err = scenario.Provider.ValidateOverrides(scenario.InputGroup, &scenario.InputAlert); err != nil {
+				t.Errorf("unexpected error: %s", err)
+			}
+		})
+	}
+}

alerting/provider/email/email.go

@@ -0,0 +1,206 @@
+package email
+
+import (
+	"crypto/tls"
+	"errors"
+	"fmt"
+	"math"
+	"strings"
+
+	"github.com/TwiN/gatus/v5/alerting/alert"
+	"github.com/TwiN/gatus/v5/client"
+	"github.com/TwiN/gatus/v5/config/endpoint"
+	gomail "gopkg.in/mail.v2"
+	"gopkg.in/yaml.v3"
+)
+
+var (
+	ErrDuplicateGroupOverride = errors.New("duplicate group override")
+	ErrMissingFromOrToFields  = errors.New("from and to fields are required")
+	ErrInvalidPort            = errors.New("port must be between 1 and 65535 inclusively")
+	ErrMissingHost            = errors.New("host is required")
+)
+
+type Config struct {
+	From     string `yaml:"from"`
+	Username string `yaml:"username"`
+	Password string `yaml:"password"`
+	Host     string `yaml:"host"`
+	Port     int    `yaml:"port"`
+	To       string `yaml:"to"`
+
+	// ClientConfig is the configuration of the client used to communicate with the provider's target
+	ClientConfig *client.Config `yaml:"client,omitempty"`
+}
+
+func (cfg *Config) Validate() error {
+	if len(cfg.From) == 0 || len(cfg.To) == 0 {
+		return ErrMissingFromOrToFields
+	}
+	if cfg.Port < 1 || cfg.Port > math.MaxUint16 {
+		return ErrInvalidPort
+	}
+	if len(cfg.Host) == 0 {
+		return ErrMissingHost
+	}
+	return nil
+}
+
+func (cfg *Config) Merge(override *Config) {
+	if override.ClientConfig != nil {
+		cfg.ClientConfig = override.ClientConfig
+	}
+	if len(override.From) > 0 {
+		cfg.From = override.From
+	}
+	if len(override.Username) > 0 {
+		cfg.Username = override.Username
+	}
+	if len(override.Password) > 0 {
+		cfg.Password = override.Password
+	}
+	if len(override.Host) > 0 {
+		cfg.Host = override.Host
+	}
+	if override.Port > 0 {
+		cfg.Port = override.Port
+	}
+	if len(override.To) > 0 {
+		cfg.To = override.To
+	}
+}
+
+// AlertProvider is the configuration necessary for sending an alert using SMTP
+type AlertProvider struct {
+	DefaultConfig Config `yaml:",inline"`
+
+	// DefaultAlert is the default alert configuration to use for endpoints with an alert of the appropriate type
+	DefaultAlert *alert.Alert `yaml:"default-alert,omitempty"`
+
+	// Overrides is a list of Override that may be prioritized over the default configuration
+	Overrides []Override `yaml:"overrides,omitempty"`
+}
+
+// Override is a case under which the default integration is overridden
+type Override struct {
+	Group  string `yaml:"group"`
+	Config `yaml:",inline"`
+}
+
+// Validate the provider's configuration
+func (provider *AlertProvider) Validate() error {
+	registeredGroups := make(map[string]bool)
+	if provider.Overrides != nil {
+		for _, override := range provider.Overrides {
+			if isAlreadyRegistered := registeredGroups[override.Group]; isAlreadyRegistered || override.Group == "" || len(override.To) == 0 {
+				return ErrDuplicateGroupOverride
+			}
+			registeredGroups[override.Group] = true
+		}
+	}
+	return provider.DefaultConfig.Validate()
+}
+
+// Send an alert using the provider
+func (provider *AlertProvider) Send(ep *endpoint.Endpoint, alert *alert.Alert, result *endpoint.Result, resolved bool) error {
+	cfg, err := provider.GetConfig(ep.Group, alert)
+	if err != nil {
+		return err
+	}
+	var username string
+	if len(cfg.Username) > 0 {
+		username = cfg.Username
+	} else {
+		username = cfg.From
+	}
+	subject, body := provider.buildMessageSubjectAndBody(ep, alert, result, resolved)
+	m := gomail.NewMessage()
+	m.SetHeader("From", cfg.From)
+	m.SetHeader("To", strings.Split(cfg.To, ",")...)
+	m.SetHeader("Subject", subject)
+	m.SetBody("text/plain", body)
+	var d *gomail.Dialer
+	if len(cfg.Password) == 0 {
+		// Get the domain in the From address
+		localName := "localhost"
+		fromParts := strings.Split(cfg.From, `@`)
+		if len(fromParts) == 2 {
+			localName = fromParts[1]
+		}
+		// Create a dialer with no authentication
+		d = &gomail.Dialer{Host: cfg.Host, Port: cfg.Port, LocalName: localName}
+	} else {
+		// Create an authenticated dialer
+		d = gomail.NewDialer(cfg.Host, cfg.Port, username, cfg.Password)
+	}
+	if cfg.ClientConfig != nil && cfg.ClientConfig.Insecure {
+		d.TLSConfig = &tls.Config{InsecureSkipVerify: true}
+	}
+	return d.DialAndSend(m)
+}
+
+// buildMessageSubjectAndBody builds the message subject and body
+func (provider *AlertProvider) buildMessageSubjectAndBody(ep *endpoint.Endpoint, alert *alert.Alert, result *endpoint.Result, resolved bool) (string, string) {
+	var subject, message string
+	if resolved {
+		subject = fmt.Sprintf("[%s] Alert resolved", ep.DisplayName())
+		message = fmt.Sprintf("An alert for %s has been resolved after passing successfully %d time(s) in a row", ep.DisplayName(), alert.SuccessThreshold)
+	} else {
+		subject = fmt.Sprintf("[%s] Alert triggered", ep.DisplayName())
+		message = fmt.Sprintf("An alert for %s has been triggered due to having failed %d time(s) in a row", ep.DisplayName(), alert.FailureThreshold)
+	}
+	var formattedConditionResults string
+	if len(result.ConditionResults) > 0 {
+		formattedConditionResults = "\n\nCondition results:\n"
+		for _, conditionResult := range result.ConditionResults {
+			var prefix string
+			if conditionResult.Success {
+				prefix = "✅"
+			} else {
+				prefix = "❌"
+			}
+			formattedConditionResults += fmt.Sprintf("%s %s\n", prefix, conditionResult.Condition)
+		}
+	}
+	var description string
+	if alertDescription := alert.GetDescription(); len(alertDescription) > 0 {
+		description = "\n\nAlert description: " + alertDescription
+	}
+	return subject, message + description + formattedConditionResults
+}
+
+// GetDefaultAlert returns the provider's default alert configuration
+func (provider *AlertProvider) GetDefaultAlert() *alert.Alert {
+	return provider.DefaultAlert
+}
+
+// GetConfig returns the configuration for the provider with the overrides applied
+func (provider *AlertProvider) GetConfig(group string, alert *alert.Alert) (*Config, error) {
+	cfg := provider.DefaultConfig
+	// Handle group overrides
+	if provider.Overrides != nil {
+		for _, override := range provider.Overrides {
+			if group == override.Group {
+				cfg.Merge(&override.Config)
+				break
+			}
+		}
+	}
+	// Handle alert overrides
+	if len(alert.ProviderOverride) != 0 {
+		overrideConfig := Config{}
+		if err := yaml.Unmarshal(alert.ProviderOverrideAsBytes(), &overrideConfig); err != nil {
+			return nil, err
+		}
+		cfg.Merge(&overrideConfig)
+	}
+	// Validate the configuration
+	err := cfg.Validate()
+	return &cfg, err
+}
+
+// ValidateOverrides validates the alert's provider override and, if present, the group override
+func (provider *AlertProvider) ValidateOverrides(group string, alert *alert.Alert) error {
+	_, err := provider.GetConfig(group, alert)
+	return err
+}

alerting/provider/email/email_test.go

@@ -0,0 +1,232 @@
+package email
+
+import (
+	"testing"
+
+	"github.com/TwiN/gatus/v5/alerting/alert"
+	"github.com/TwiN/gatus/v5/config/endpoint"
+)
+
+func TestAlertProvider_Validate(t *testing.T) {
+	invalidProvider := AlertProvider{}
+	if err := invalidProvider.Validate(); err == nil {
+		t.Error("provider shouldn't have been valid")
+	}
+	validProvider := AlertProvider{DefaultConfig: Config{From: "from@example.com", Password: "password", Host: "smtp.gmail.com", Port: 587, To: "to@example.com"}}
+	if err := validProvider.Validate(); err != nil {
+		t.Error("provider should've been valid")
+	}
+}
+
+func TestAlertProvider_ValidateWithNoCredentials(t *testing.T) {
+	validProvider := AlertProvider{DefaultConfig: Config{From: "from@example.com", Host: "smtp-relay.gmail.com", Port: 587, To: "to@example.com"}}
+	if err := validProvider.Validate(); err != nil {
+		t.Error("provider should've been valid")
+	}
+}
+
+func TestAlertProvider_ValidateWithOverride(t *testing.T) {
+	providerWithInvalidOverrideGroup := AlertProvider{
+		Overrides: []Override{
+			{
+				Config: Config{To: "to@example.com"},
+				Group:  "",
+			},
+		},
+	}
+	if err := providerWithInvalidOverrideGroup.Validate(); err == nil {
+		t.Error("provider Group shouldn't have been valid")
+	}
+	providerWithInvalidOverrideTo := AlertProvider{
+		Overrides: []Override{
+			{
+				Config: Config{To: ""},
+				Group:  "group",
+			},
+		},
+	}
+	if err := providerWithInvalidOverrideTo.Validate(); err == nil {
+		t.Error("provider integration key shouldn't have been valid")
+	}
+	providerWithValidOverride := AlertProvider{
+		DefaultConfig: Config{
+			From:     "from@example.com",
+			Password: "password",
+			Host:     "smtp.gmail.com",
+			Port:     587,
+			To:       "to@example.com",
+		},
+		Overrides: []Override{
+			{
+				Config: Config{To: "to@example.com"},
+				Group:  "group",
+			},
+		},
+	}
+	if err := providerWithValidOverride.Validate(); err != nil {
+		t.Error("provider should've been valid")
+	}
+}
+
+func TestAlertProvider_buildRequestBody(t *testing.T) {
+	firstDescription := "description-1"
+	secondDescription := "description-2"
+	scenarios := []struct {
+		Name            string
+		Provider        AlertProvider
+		Alert           alert.Alert
+		Resolved        bool
+		ExpectedSubject string
+		ExpectedBody    string
+	}{
+		{
+			Name:            "triggered",
+			Provider:        AlertProvider{},
+			Alert:           alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:        false,
+			ExpectedSubject: "[endpoint-name] Alert triggered",
+			ExpectedBody:    "An alert for endpoint-name has been triggered due to having failed 3 time(s) in a row\n\nAlert description: description-1\n\nCondition results:\n❌ [CONNECTED] == true\n❌ [STATUS] == 200\n",
+		},
+		{
+			Name:            "resolved",
+			Provider:        AlertProvider{},
+			Alert:           alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:        true,
+			ExpectedSubject: "[endpoint-name] Alert resolved",
+			ExpectedBody:    "An alert for endpoint-name has been resolved after passing successfully 5 time(s) in a row\n\nAlert description: description-2\n\nCondition results:\n✅ [CONNECTED] == true\n✅ [STATUS] == 200\n",
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			subject, body := scenario.Provider.buildMessageSubjectAndBody(
+				&endpoint.Endpoint{Name: "endpoint-name"},
+				&scenario.Alert,
+				&endpoint.Result{
+					ConditionResults: []*endpoint.ConditionResult{
+						{Condition: "[CONNECTED] == true", Success: scenario.Resolved},
+						{Condition: "[STATUS] == 200", Success: scenario.Resolved},
+					},
+				},
+				scenario.Resolved,
+			)
+			if subject != scenario.ExpectedSubject {
+				t.Errorf("expected subject to be %s, got %s", scenario.ExpectedSubject, subject)
+			}
+			if body != scenario.ExpectedBody {
+				t.Errorf("expected body to be %s, got %s", scenario.ExpectedBody, body)
+			}
+		})
+	}
+}
+
+func TestAlertProvider_GetDefaultAlert(t *testing.T) {
+	if (&AlertProvider{DefaultAlert: &alert.Alert{}}).GetDefaultAlert() == nil {
+		t.Error("expected default alert to be not nil")
+	}
+	if (&AlertProvider{DefaultAlert: nil}).GetDefaultAlert() != nil {
+		t.Error("expected default alert to be nil")
+	}
+}
+
+func TestAlertProvider_GetConfig(t *testing.T) {
+	scenarios := []struct {
+		Name           string
+		Provider       AlertProvider
+		InputGroup     string
+		InputAlert     alert.Alert
+		ExpectedOutput Config
+	}{
+		{
+			Name: "provider-no-override-specify-no-group-should-default",
+			Provider: AlertProvider{
+				DefaultConfig: Config{From: "from@example.com", To: "to@example.com", Host: "smtp.gmail.com", Port: 587, Password: "password"},
+				Overrides:     nil,
+			},
+			InputGroup:     "",
+			InputAlert:     alert.Alert{},
+			ExpectedOutput: Config{From: "from@example.com", To: "to@example.com", Host: "smtp.gmail.com", Port: 587, Password: "password"},
+		},
+		{
+			Name: "provider-no-override-specify-group-should-default",
+			Provider: AlertProvider{
+				DefaultConfig: Config{From: "from@example.com", To: "to@example.com", Host: "smtp.gmail.com", Port: 587, Password: "password"},
+				Overrides:     nil,
+			},
+			InputGroup:     "group",
+			InputAlert:     alert.Alert{},
+			ExpectedOutput: Config{From: "from@example.com", To: "to@example.com", Host: "smtp.gmail.com", Port: 587, Password: "password"},
+		},
+		{
+			Name: "provider-with-override-specify-no-group-should-default",
+			Provider: AlertProvider{
+				DefaultConfig: Config{From: "from@example.com", To: "to@example.com", Host: "smtp.gmail.com", Port: 587, Password: "password"},
+				Overrides: []Override{
+					{
+						Group:  "group",
+						Config: Config{To: "to01@example.com"},
+					},
+				},
+			},
+			InputGroup:     "",
+			InputAlert:     alert.Alert{},
+			ExpectedOutput: Config{From: "from@example.com", To: "to@example.com", Host: "smtp.gmail.com", Port: 587, Password: "password"},
+		},
+		{
+			Name: "provider-with-override-specify-group-should-override",
+			Provider: AlertProvider{
+				DefaultConfig: Config{From: "from@example.com", To: "to@example.com", Host: "smtp.gmail.com", Port: 587, Password: "password"},
+				Overrides: []Override{
+					{
+						Group:  "group",
+						Config: Config{To: "group-to@example.com"},
+					},
+				},
+			},
+			InputGroup:     "group",
+			InputAlert:     alert.Alert{},
+			ExpectedOutput: Config{From: "from@example.com", To: "group-to@example.com", Host: "smtp.gmail.com", Port: 587, Password: "password"},
+		},
+		{
+			Name: "provider-with-group-override-and-alert-override--alert-override-should-take-precedence",
+			Provider: AlertProvider{
+				DefaultConfig: Config{From: "from@example.com", To: "to@example.com", Host: "smtp.gmail.com", Port: 587, Password: "password"},
+				Overrides: []Override{
+					{
+						Group:  "group",
+						Config: Config{To: "group-to@example.com"},
+					},
+				},
+			},
+			InputGroup:     "group",
+			InputAlert:     alert.Alert{ProviderOverride: map[string]any{"to": "alert-to@example.com", "host": "smtp.example.com", "port": 588, "password": "hunter2"}},
+			ExpectedOutput: Config{From: "from@example.com", To: "alert-to@example.com", Host: "smtp.example.com", Port: 588, Password: "hunter2"},
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			got, err := scenario.Provider.GetConfig(scenario.InputGroup, &scenario.InputAlert)
+			if err != nil {
+				t.Fatalf("unexpected error: %s", err)
+			}
+			if got.From != scenario.ExpectedOutput.From {
+				t.Errorf("expected from to be %s, got %s", scenario.ExpectedOutput.From, got.From)
+			}
+			if got.To != scenario.ExpectedOutput.To {
+				t.Errorf("expected to be %s, got %s", scenario.ExpectedOutput.To, got.To)
+			}
+			if got.Host != scenario.ExpectedOutput.Host {
+				t.Errorf("expected host to be %s, got %s", scenario.ExpectedOutput.Host, got.Host)
+			}
+			if got.Port != scenario.ExpectedOutput.Port {
+				t.Errorf("expected port to be %d, got %d", scenario.ExpectedOutput.Port, got.Port)
+			}
+			if got.Password != scenario.ExpectedOutput.Password {
+				t.Errorf("expected password to be %s, got %s", scenario.ExpectedOutput.Password, got.Password)
+			}
+			// Test ValidateOverrides as well, since it really just calls GetConfig
+			if err = scenario.Provider.ValidateOverrides(scenario.InputGroup, &scenario.InputAlert); err != nil {
+				t.Errorf("unexpected error: %s", err)
+			}
+		})
+	}
+}

alerting/provider/gitea/gitea.go

@@ -0,0 +1,217 @@
+package gitea
+
+import (
+	"crypto/tls"
+	"errors"
+	"fmt"
+	"net/http"
+	"net/url"
+	"strings"
+
+	"code.gitea.io/sdk/gitea"
+	"github.com/TwiN/gatus/v5/alerting/alert"
+	"github.com/TwiN/gatus/v5/client"
+	"github.com/TwiN/gatus/v5/config/endpoint"
+	"gopkg.in/yaml.v3"
+)
+
+var (
+	ErrRepositoryURLNotSet  = errors.New("repository-url not set")
+	ErrInvalidRepositoryURL = errors.New("invalid repository-url")
+	ErrTokenNotSet          = errors.New("token not set")
+)
+
+type Config struct {
+	RepositoryURL string   `yaml:"repository-url"`      // The URL of the Gitea repository to create issues in
+	Token         string   `yaml:"token"`               // Token requires at least RW on issues and RO on metadata
+	Assignees     []string `yaml:"assignees,omitempty"` // Assignees is a list of users to assign the issue to
+
+	username        string
+	repositoryOwner string
+	repositoryName  string
+	giteaClient     *gitea.Client
+
+	// ClientConfig is the configuration of the client used to communicate with the provider's target
+	ClientConfig *client.Config `yaml:"client,omitempty"`
+}
+
+func (cfg *Config) Validate() error {
+	if len(cfg.RepositoryURL) == 0 {
+		return ErrRepositoryURLNotSet
+	}
+	if len(cfg.Token) == 0 {
+		return ErrTokenNotSet
+	}
+	// Validate format of the repository URL
+	repositoryURL, err := url.Parse(cfg.RepositoryURL)
+	if err != nil {
+		return err
+	}
+	baseURL := repositoryURL.Scheme + "://" + repositoryURL.Host
+	pathParts := strings.Split(repositoryURL.Path, "/")
+	if len(pathParts) != 3 {
+		return ErrInvalidRepositoryURL
+	}
+	if cfg.repositoryOwner == pathParts[1] && cfg.repositoryName == pathParts[2] && cfg.giteaClient != nil {
+		// Already validated, let's skip the rest of the validation to avoid unnecessary API calls
+		return nil
+	}
+	cfg.repositoryOwner = pathParts[1]
+	cfg.repositoryName = pathParts[2]
+	opts := []gitea.ClientOption{
+		gitea.SetToken(cfg.Token),
+	}
+	if cfg.ClientConfig != nil && cfg.ClientConfig.Insecure {
+		// add new http client for skip verify
+		httpClient := &http.Client{
+			Transport: &http.Transport{
+				TLSClientConfig: &tls.Config{InsecureSkipVerify: true},
+			},
+		}
+		opts = append(opts, gitea.SetHTTPClient(httpClient))
+	}
+	cfg.giteaClient, err = gitea.NewClient(baseURL, opts...)
+	if err != nil {
+		return err
+	}
+	user, _, err := cfg.giteaClient.GetMyUserInfo()
+	if err != nil {
+		return err
+	}
+	cfg.username = user.UserName
+	return nil
+}
+
+func (cfg *Config) Merge(override *Config) {
+	if override.ClientConfig != nil {
+		cfg.ClientConfig = override.ClientConfig
+	}
+	if len(override.RepositoryURL) > 0 {
+		cfg.RepositoryURL = override.RepositoryURL
+	}
+	if len(override.Token) > 0 {
+		cfg.Token = override.Token
+	}
+	if len(override.Assignees) > 0 {
+		cfg.Assignees = override.Assignees
+	}
+}
+
+// AlertProvider is the configuration necessary for sending an alert using Discord
+type AlertProvider struct {
+	DefaultConfig Config `yaml:",inline"`
+
+	// DefaultAlert is the default alert configuration to use for endpoints with an alert of the appropriate type
+	DefaultAlert *alert.Alert `yaml:"default-alert,omitempty"`
+}
+
+// Validate the provider's configuration
+func (provider *AlertProvider) Validate() error {
+	return provider.DefaultConfig.Validate()
+}
+
+// Send creates an issue in the designed RepositoryURL if the resolved parameter passed is false,
+// or closes the relevant issue(s) if the resolved parameter passed is true.
+func (provider *AlertProvider) Send(ep *endpoint.Endpoint, alert *alert.Alert, result *endpoint.Result, resolved bool) error {
+	cfg, err := provider.GetConfig(ep.Group, alert)
+	if err != nil {
+		return err
+	}
+	title := "alert(gatus): " + ep.DisplayName()
+	if !resolved {
+		_, _, err = cfg.giteaClient.CreateIssue(
+			cfg.repositoryOwner,
+			cfg.repositoryName,
+			gitea.CreateIssueOption{
+				Title:     title,
+				Body:      provider.buildIssueBody(ep, alert, result),
+				Assignees: cfg.Assignees,
+			},
+		)
+		if err != nil {
+			return fmt.Errorf("failed to create issue: %w", err)
+		}
+		return nil
+	}
+	issues, _, err := cfg.giteaClient.ListRepoIssues(
+		cfg.repositoryOwner,
+		cfg.repositoryName,
+		gitea.ListIssueOption{
+			State:     gitea.StateOpen,
+			CreatedBy: cfg.username,
+			ListOptions: gitea.ListOptions{
+				Page: 100,
+			},
+		},
+	)
+	if err != nil {
+		return fmt.Errorf("failed to list issues: %w", err)
+	}
+	for _, issue := range issues {
+		if issue.Title == title {
+			stateClosed := gitea.StateClosed
+			_, _, err = cfg.giteaClient.EditIssue(
+				cfg.repositoryOwner,
+				cfg.repositoryName,
+				issue.ID,
+				gitea.EditIssueOption{
+					State: &stateClosed,
+				},
+			)
+			if err != nil {
+				return fmt.Errorf("failed to close issue: %w", err)
+			}
+		}
+	}
+	return nil
+}
+
+// buildIssueBody builds the body of the issue
+func (provider *AlertProvider) buildIssueBody(ep *endpoint.Endpoint, alert *alert.Alert, result *endpoint.Result) string {
+	var formattedConditionResults string
+	if len(result.ConditionResults) > 0 {
+		formattedConditionResults = "\n\n## Condition results\n"
+		for _, conditionResult := range result.ConditionResults {
+			var prefix string
+			if conditionResult.Success {
+				prefix = ":white_check_mark:"
+			} else {
+				prefix = ":x:"
+			}
+			formattedConditionResults += fmt.Sprintf("- %s - `%s`\n", prefix, conditionResult.Condition)
+		}
+	}
+	var description string
+	if alertDescription := alert.GetDescription(); len(alertDescription) > 0 {
+		description = ":\n> " + alertDescription
+	}
+	message := fmt.Sprintf("An alert for **%s** has been triggered due to having failed %d time(s) in a row", ep.DisplayName(), alert.FailureThreshold)
+	return message + description + formattedConditionResults
+}
+
+// GetDefaultAlert returns the provider's default alert configuration
+func (provider *AlertProvider) GetDefaultAlert() *alert.Alert {
+	return provider.DefaultAlert
+}
+
+// GetConfig returns the configuration for the provider with the overrides applied
+func (provider *AlertProvider) GetConfig(group string, alert *alert.Alert) (*Config, error) {
+	cfg := provider.DefaultConfig
+	// Handle alert overrides
+	if len(alert.ProviderOverride) != 0 {
+		overrideConfig := Config{}
+		if err := yaml.Unmarshal(alert.ProviderOverrideAsBytes(), &overrideConfig); err != nil {
+			return nil, err
+		}
+		cfg.Merge(&overrideConfig)
+	}
+	// Validate the configuration (we're returning the cfg here even if there's an error mostly for testing purposes)
+	err := cfg.Validate()
+	return &cfg, err
+}
+
+// ValidateOverrides validates the alert's provider override and, if present, the group override
+func (provider *AlertProvider) ValidateOverrides(group string, alert *alert.Alert) error {
+	_, err := provider.GetConfig(group, alert)
+	return err
+}

alerting/provider/gitea/gitea_test.go

@@ -0,0 +1,229 @@
+package gitea
+
+import (
+	"net/http"
+	"strings"
+	"testing"
+
+	"code.gitea.io/sdk/gitea"
+	"github.com/TwiN/gatus/v5/alerting/alert"
+	"github.com/TwiN/gatus/v5/client"
+	"github.com/TwiN/gatus/v5/config/endpoint"
+	"github.com/TwiN/gatus/v5/test"
+)
+
+func TestAlertProvider_Validate(t *testing.T) {
+	scenarios := []struct {
+		Name          string
+		Provider      AlertProvider
+		ExpectedError bool
+	}{
+		{
+			Name:          "invalid",
+			Provider:      AlertProvider{DefaultConfig: Config{RepositoryURL: "", Token: ""}},
+			ExpectedError: true,
+		},
+		{
+			Name:          "invalid-token",
+			Provider:      AlertProvider{DefaultConfig: Config{RepositoryURL: "https://gitea.com/TwiN/test", Token: "12345"}},
+			ExpectedError: true,
+		},
+		{
+			Name:          "missing-repository-name",
+			Provider:      AlertProvider{DefaultConfig: Config{RepositoryURL: "https://gitea.com/TwiN", Token: "12345"}},
+			ExpectedError: true,
+		},
+		{
+			Name:          "enterprise-client",
+			Provider:      AlertProvider{DefaultConfig: Config{RepositoryURL: "https://gitea.example.com/TwiN/test", Token: "12345"}},
+			ExpectedError: false,
+		},
+		{
+			Name:          "invalid-url",
+			Provider:      AlertProvider{DefaultConfig: Config{RepositoryURL: "gitea.com/TwiN/test", Token: "12345"}},
+			ExpectedError: true,
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			err := scenario.Provider.Validate()
+			if scenario.ExpectedError && err == nil {
+				t.Error("expected error, got none")
+			}
+			if !scenario.ExpectedError && err != nil && !strings.Contains(err.Error(), "user does not exist") && !strings.Contains(err.Error(), "no such host") {
+				t.Error("expected no error, got", err.Error())
+			}
+		})
+	}
+}
+
+func TestAlertProvider_Send(t *testing.T) {
+	defer client.InjectHTTPClient(nil)
+	firstDescription := "description-1"
+	secondDescription := "description-2"
+	scenarios := []struct {
+		Name             string
+		Provider         AlertProvider
+		Alert            alert.Alert
+		Resolved         bool
+		MockRoundTripper test.MockRoundTripper
+		ExpectedError    bool
+	}{
+		{
+			Name:          "triggered-error",
+			Provider:      AlertProvider{DefaultConfig: Config{RepositoryURL: "https://gitea.com/TwiN/test", Token: "12345"}},
+			Alert:         alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:      false,
+			ExpectedError: true,
+		},
+		{
+			Name:          "resolved-error",
+			Provider:      AlertProvider{DefaultConfig: Config{RepositoryURL: "https://gitea.com/TwiN/test", Token: "12345"}},
+			Alert:         alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:      true,
+			ExpectedError: true,
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			cfg, err := scenario.Provider.GetConfig("", &scenario.Alert)
+			if err != nil && !strings.Contains(err.Error(), "user does not exist") && !strings.Contains(err.Error(), "no such host") {
+				t.Error("expected no error, got", err.Error())
+			}
+			cfg.giteaClient, _ = gitea.NewClient("https://gitea.com")
+			client.InjectHTTPClient(&http.Client{Transport: scenario.MockRoundTripper})
+			err = scenario.Provider.Send(
+				&endpoint.Endpoint{Name: "endpoint-name", Group: "endpoint-group"},
+				&scenario.Alert,
+				&endpoint.Result{
+					ConditionResults: []*endpoint.ConditionResult{
+						{Condition: "[CONNECTED] == true", Success: scenario.Resolved},
+						{Condition: "[STATUS] == 200", Success: scenario.Resolved},
+					},
+				},
+				scenario.Resolved,
+			)
+			if scenario.ExpectedError && err == nil {
+				t.Error("expected error, got none")
+			}
+			if !scenario.ExpectedError && err != nil {
+				t.Error("expected no error, got", err.Error())
+			}
+		})
+	}
+}
+
+func TestAlertProvider_buildRequestBody(t *testing.T) {
+	firstDescription := "description-1"
+	scenarios := []struct {
+		Name         string
+		Endpoint     endpoint.Endpoint
+		Provider     AlertProvider
+		Alert        alert.Alert
+		NoConditions bool
+		ExpectedBody string
+	}{
+		{
+			Name:         "triggered",
+			Endpoint:     endpoint.Endpoint{Name: "endpoint-name", URL: "https://example.org"},
+			Provider:     AlertProvider{},
+			Alert:        alert.Alert{Description: &firstDescription, FailureThreshold: 3},
+			ExpectedBody: "An alert for **endpoint-name** has been triggered due to having failed 3 time(s) in a row:\n> description-1\n\n## Condition results\n- :white_check_mark: - `[CONNECTED] == true`\n- :x: - `[STATUS] == 200`",
+		},
+		{
+			Name:         "triggered-with-no-description",
+			Endpoint:     endpoint.Endpoint{Name: "endpoint-name", URL: "https://example.org"},
+			Provider:     AlertProvider{},
+			Alert:        alert.Alert{FailureThreshold: 10},
+			ExpectedBody: "An alert for **endpoint-name** has been triggered due to having failed 10 time(s) in a row\n\n## Condition results\n- :white_check_mark: - `[CONNECTED] == true`\n- :x: - `[STATUS] == 200`",
+		},
+		{
+			Name:         "triggered-with-no-conditions",
+			NoConditions: true,
+			Endpoint:     endpoint.Endpoint{Name: "endpoint-name", URL: "https://example.org"},
+			Provider:     AlertProvider{},
+			Alert:        alert.Alert{Description: &firstDescription, FailureThreshold: 10},
+			ExpectedBody: "An alert for **endpoint-name** has been triggered due to having failed 10 time(s) in a row:\n> description-1",
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			var conditionResults []*endpoint.ConditionResult
+			if !scenario.NoConditions {
+				conditionResults = []*endpoint.ConditionResult{
+					{Condition: "[CONNECTED] == true", Success: true},
+					{Condition: "[STATUS] == 200", Success: false},
+				}
+			}
+			body := scenario.Provider.buildIssueBody(
+				&scenario.Endpoint,
+				&scenario.Alert,
+				&endpoint.Result{ConditionResults: conditionResults},
+			)
+			if strings.TrimSpace(body) != strings.TrimSpace(scenario.ExpectedBody) {
+				t.Errorf("expected:\n%s\ngot:\n%s", scenario.ExpectedBody, body)
+			}
+		})
+	}
+}
+
+func TestAlertProvider_GetDefaultAlert(t *testing.T) {
+	if (&AlertProvider{DefaultAlert: &alert.Alert{}}).GetDefaultAlert() == nil {
+		t.Error("expected default alert to be not nil")
+	}
+	if (&AlertProvider{DefaultAlert: nil}).GetDefaultAlert() != nil {
+		t.Error("expected default alert to be nil")
+	}
+}
+
+func TestAlertProvider_GetConfig(t *testing.T) {
+	scenarios := []struct {
+		Name           string
+		Provider       AlertProvider
+		InputAlert     alert.Alert
+		ExpectedOutput Config
+	}{
+		{
+			Name: "provider-no-override-should-default",
+			Provider: AlertProvider{
+				DefaultConfig: Config{RepositoryURL: "https://gitea.com/TwiN/test", Token: "12345"},
+			},
+			InputAlert:     alert.Alert{},
+			ExpectedOutput: Config{RepositoryURL: "https://gitea.com/TwiN/test", Token: "12345"},
+		},
+		{
+			Name: "provider-with-alert-override",
+			Provider: AlertProvider{
+				DefaultConfig: Config{RepositoryURL: "https://gitea.com/TwiN/test", Token: "12345"},
+			},
+			InputAlert:     alert.Alert{ProviderOverride: map[string]any{"repository-url": "https://gitea.com/TwiN/alert-test", "token": "54321", "assignees": []string{"TwiN"}}},
+			ExpectedOutput: Config{RepositoryURL: "https://gitea.com/TwiN/alert-test", Token: "54321", Assignees: []string{"TwiN"}},
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			got, err := scenario.Provider.GetConfig("", &scenario.InputAlert)
+			if err != nil && !strings.Contains(err.Error(), "user does not exist") && !strings.Contains(err.Error(), "no such host") {
+				t.Fatalf("unexpected error: %s", err)
+			}
+			if got.RepositoryURL != scenario.ExpectedOutput.RepositoryURL {
+				t.Errorf("expected repository URL %s, got %s", scenario.ExpectedOutput.RepositoryURL, got.RepositoryURL)
+			}
+			if got.Token != scenario.ExpectedOutput.Token {
+				t.Errorf("expected token %s, got %s", scenario.ExpectedOutput.Token, got.Token)
+			}
+			if len(got.Assignees) != len(scenario.ExpectedOutput.Assignees) {
+				t.Errorf("expected %d assignees, got %d", len(scenario.ExpectedOutput.Assignees), len(got.Assignees))
+			}
+			for i, assignee := range got.Assignees {
+				if assignee != scenario.ExpectedOutput.Assignees[i] {
+					t.Errorf("expected assignee %s, got %s", scenario.ExpectedOutput.Assignees[i], assignee)
+				}
+			}
+			// Test ValidateOverrides as well, since it really just calls GetConfig
+			if err = scenario.Provider.ValidateOverrides("", &scenario.InputAlert); err != nil && !strings.Contains(err.Error(), "user does not exist") {
+				t.Errorf("unexpected error: %s", err)
+			}
+		})
+	}
+}

alerting/provider/github/github.go

@@ -0,0 +1,190 @@
+package github
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"net/url"
+	"strings"
+	"time"
+
+	"github.com/TwiN/gatus/v5/alerting/alert"
+	"github.com/TwiN/gatus/v5/config/endpoint"
+	"github.com/google/go-github/v48/github"
+	"golang.org/x/oauth2"
+	"gopkg.in/yaml.v3"
+)
+
+var (
+	ErrRepositoryURLNotSet  = errors.New("repository-url not set")
+	ErrInvalidRepositoryURL = errors.New("invalid repository-url")
+	ErrTokenNotSet          = errors.New("token not set")
+)
+
+type Config struct {
+	RepositoryURL string `yaml:"repository-url"` // The URL of the GitHub repository to create issues in
+	Token         string `yaml:"token"`          // Token requires at least RW on issues and RO on metadata
+
+	username        string
+	repositoryOwner string
+	repositoryName  string
+	githubClient    *github.Client
+}
+
+func (cfg *Config) Validate() error {
+	if len(cfg.RepositoryURL) == 0 {
+		return ErrRepositoryURLNotSet
+	}
+	if len(cfg.Token) == 0 {
+		return ErrTokenNotSet
+	}
+	// Validate format of the repository URL
+	repositoryURL, err := url.Parse(cfg.RepositoryURL)
+	if err != nil {
+		return err
+	}
+	baseURL := repositoryURL.Scheme + "://" + repositoryURL.Host
+	pathParts := strings.Split(repositoryURL.Path, "/")
+	if len(pathParts) != 3 {
+		return ErrInvalidRepositoryURL
+	}
+	if cfg.repositoryOwner == pathParts[1] && cfg.repositoryName == pathParts[2] && cfg.githubClient != nil {
+		// Already validated, let's skip the rest of the validation to avoid unnecessary API calls
+		return nil
+	}
+	cfg.repositoryOwner = pathParts[1]
+	cfg.repositoryName = pathParts[2]
+	// Create oauth2 HTTP client with GitHub token
+	httpClientWithStaticTokenSource := oauth2.NewClient(context.Background(), oauth2.StaticTokenSource(&oauth2.Token{
+		AccessToken: cfg.Token,
+	}))
+	// Create GitHub client
+	if baseURL == "https://github.com" {
+		cfg.githubClient = github.NewClient(httpClientWithStaticTokenSource)
+	} else {
+		cfg.githubClient, err = github.NewEnterpriseClient(baseURL, baseURL, httpClientWithStaticTokenSource)
+		if err != nil {
+			return fmt.Errorf("failed to create enterprise GitHub client: %w", err)
+		}
+	}
+	// Retrieve the username once to validate that the token is valid
+	ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
+	defer cancel()
+	user, _, err := cfg.githubClient.Users.Get(ctx, "")
+	if err != nil {
+		return fmt.Errorf("failed to retrieve GitHub user: %w", err)
+	}
+	cfg.username = *user.Login
+	return nil
+}
+
+func (cfg *Config) Merge(override *Config) {
+	if len(override.RepositoryURL) > 0 {
+		cfg.RepositoryURL = override.RepositoryURL
+	}
+	if len(override.Token) > 0 {
+		cfg.Token = override.Token
+	}
+}
+
+// AlertProvider is the configuration necessary for sending an alert using Discord
+type AlertProvider struct {
+	DefaultConfig Config `yaml:",inline"`
+
+	// DefaultAlert is the default alert configuration to use for endpoints with an alert of the appropriate type
+	DefaultAlert *alert.Alert `yaml:"default-alert,omitempty"`
+}
+
+// Validate the provider's configuration
+func (provider *AlertProvider) Validate() error {
+	return provider.DefaultConfig.Validate()
+}
+
+// Send creates an issue in the designed RepositoryURL if the resolved parameter passed is false,
+// or closes the relevant issue(s) if the resolved parameter passed is true.
+func (provider *AlertProvider) Send(ep *endpoint.Endpoint, alert *alert.Alert, result *endpoint.Result, resolved bool) error {
+	cfg, err := provider.GetConfig(ep.Group, alert)
+	if err != nil {
+		return err
+	}
+	title := "alert(gatus): " + ep.DisplayName()
+	if !resolved {
+		_, _, err := cfg.githubClient.Issues.Create(context.Background(), cfg.repositoryOwner, cfg.repositoryName, &github.IssueRequest{
+			Title: github.String(title),
+			Body:  github.String(provider.buildIssueBody(ep, alert, result)),
+		})
+		if err != nil {
+			return fmt.Errorf("failed to create issue: %w", err)
+		}
+	} else {
+		issues, _, err := cfg.githubClient.Issues.ListByRepo(context.Background(), cfg.repositoryOwner, cfg.repositoryName, &github.IssueListByRepoOptions{
+			State:       "open",
+			Creator:     cfg.username,
+			ListOptions: github.ListOptions{PerPage: 100},
+		})
+		if err != nil {
+			return fmt.Errorf("failed to list issues: %w", err)
+		}
+		for _, issue := range issues {
+			if *issue.Title == title {
+				_, _, err = cfg.githubClient.Issues.Edit(context.Background(), cfg.repositoryOwner, cfg.repositoryName, *issue.Number, &github.IssueRequest{
+					State: github.String("closed"),
+				})
+				if err != nil {
+					return fmt.Errorf("failed to close issue: %w", err)
+				}
+			}
+		}
+	}
+	return nil
+}
+
+// buildIssueBody builds the body of the issue
+func (provider *AlertProvider) buildIssueBody(ep *endpoint.Endpoint, alert *alert.Alert, result *endpoint.Result) string {
+	var formattedConditionResults string
+	if len(result.ConditionResults) > 0 {
+		formattedConditionResults = "\n\n## Condition results\n"
+		for _, conditionResult := range result.ConditionResults {
+			var prefix string
+			if conditionResult.Success {
+				prefix = ":white_check_mark:"
+			} else {
+				prefix = ":x:"
+			}
+			formattedConditionResults += fmt.Sprintf("- %s - `%s`\n", prefix, conditionResult.Condition)
+		}
+	}
+	var description string
+	if alertDescription := alert.GetDescription(); len(alertDescription) > 0 {
+		description = ":\n> " + alertDescription
+	}
+	message := fmt.Sprintf("An alert for **%s** has been triggered due to having failed %d time(s) in a row", ep.DisplayName(), alert.FailureThreshold)
+	return message + description + formattedConditionResults
+}
+
+// GetDefaultAlert returns the provider's default alert configuration
+func (provider *AlertProvider) GetDefaultAlert() *alert.Alert {
+	return provider.DefaultAlert
+}
+
+// GetConfig returns the configuration for the provider with the overrides applied
+func (provider *AlertProvider) GetConfig(group string, alert *alert.Alert) (*Config, error) {
+	cfg := provider.DefaultConfig
+	// Handle alert overrides
+	if len(alert.ProviderOverride) != 0 {
+		overrideConfig := Config{}
+		if err := yaml.Unmarshal(alert.ProviderOverrideAsBytes(), &overrideConfig); err != nil {
+			return nil, err
+		}
+		cfg.Merge(&overrideConfig)
+	}
+	// Validate the configuration (we're returning the cfg here even if there's an error mostly for testing purposes)
+	err := cfg.Validate()
+	return &cfg, err
+}
+
+// ValidateOverrides validates the alert's provider override and, if present, the group override
+func (provider *AlertProvider) ValidateOverrides(group string, alert *alert.Alert) error {
+	_, err := provider.GetConfig(group, alert)
+	return err
+}

alerting/provider/github/github_test.go

@@ -0,0 +1,221 @@
+package github
+
+import (
+	"net/http"
+	"strings"
+	"testing"
+
+	"github.com/TwiN/gatus/v5/alerting/alert"
+	"github.com/TwiN/gatus/v5/client"
+	"github.com/TwiN/gatus/v5/config/endpoint"
+	"github.com/TwiN/gatus/v5/test"
+	"github.com/google/go-github/v48/github"
+)
+
+func TestAlertProvider_Validate(t *testing.T) {
+	scenarios := []struct {
+		Name          string
+		Provider      AlertProvider
+		ExpectedError bool
+	}{
+		{
+			Name:          "invalid",
+			Provider:      AlertProvider{DefaultConfig: Config{RepositoryURL: "", Token: ""}},
+			ExpectedError: true,
+		},
+		{
+			Name:          "invalid-token",
+			Provider:      AlertProvider{DefaultConfig: Config{RepositoryURL: "https://github.com/TwiN/test", Token: "12345"}},
+			ExpectedError: true,
+		},
+		{
+			Name:          "missing-repository-name",
+			Provider:      AlertProvider{DefaultConfig: Config{RepositoryURL: "https://github.com/TwiN", Token: "12345"}},
+			ExpectedError: true,
+		},
+		{
+			Name:          "enterprise-client",
+			Provider:      AlertProvider{DefaultConfig: Config{RepositoryURL: "https://github.example.com/TwiN/test", Token: "12345"}},
+			ExpectedError: true,
+		},
+		{
+			Name:          "invalid-url",
+			Provider:      AlertProvider{DefaultConfig: Config{RepositoryURL: "github.com/TwiN/test", Token: "12345"}},
+			ExpectedError: true,
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			err := scenario.Provider.Validate()
+			if scenario.ExpectedError && err == nil {
+				t.Error("expected error, got none")
+			}
+			if !scenario.ExpectedError && err != nil && !strings.Contains(err.Error(), "user does not exist") && !strings.Contains(err.Error(), "no such host") {
+				t.Error("expected no error, got", err.Error())
+			}
+		})
+	}
+}
+
+func TestAlertProvider_Send(t *testing.T) {
+	defer client.InjectHTTPClient(nil)
+	firstDescription := "description-1"
+	secondDescription := "description-2"
+	scenarios := []struct {
+		Name             string
+		Provider         AlertProvider
+		Alert            alert.Alert
+		Resolved         bool
+		MockRoundTripper test.MockRoundTripper
+		ExpectedError    bool
+	}{
+		{
+			Name:          "triggered-error",
+			Provider:      AlertProvider{DefaultConfig: Config{RepositoryURL: "https://github.com/TwiN/test", Token: "12345"}},
+			Alert:         alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:      false,
+			ExpectedError: true,
+		},
+		{
+			Name:          "resolved-error",
+			Provider:      AlertProvider{DefaultConfig: Config{RepositoryURL: "https://github.com/TwiN/test", Token: "12345"}},
+			Alert:         alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:      true,
+			ExpectedError: true,
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			cfg, err := scenario.Provider.GetConfig("", &scenario.Alert)
+			if err != nil && !strings.Contains(err.Error(), "failed to retrieve GitHub user") && !strings.Contains(err.Error(), "no such host") {
+				t.Error("expected no error, got", err.Error())
+			}
+			cfg.githubClient = github.NewClient(nil)
+			client.InjectHTTPClient(&http.Client{Transport: scenario.MockRoundTripper})
+			err = scenario.Provider.Send(
+				&endpoint.Endpoint{Name: "endpoint-name", Group: "endpoint-group"},
+				&scenario.Alert,
+				&endpoint.Result{
+					ConditionResults: []*endpoint.ConditionResult{
+						{Condition: "[CONNECTED] == true", Success: scenario.Resolved},
+						{Condition: "[STATUS] == 200", Success: scenario.Resolved},
+					},
+				},
+				scenario.Resolved,
+			)
+			if scenario.ExpectedError && err == nil {
+				t.Error("expected error, got none")
+			}
+			if !scenario.ExpectedError && err != nil {
+				t.Error("expected no error, got", err.Error())
+			}
+		})
+	}
+}
+
+func TestAlertProvider_buildRequestBody(t *testing.T) {
+	firstDescription := "description-1"
+	scenarios := []struct {
+		Name         string
+		Endpoint     endpoint.Endpoint
+		Provider     AlertProvider
+		Alert        alert.Alert
+		NoConditions bool
+		ExpectedBody string
+	}{
+		{
+			Name:         "triggered",
+			Endpoint:     endpoint.Endpoint{Name: "endpoint-name", URL: "https://example.org"},
+			Provider:     AlertProvider{},
+			Alert:        alert.Alert{Description: &firstDescription, FailureThreshold: 3},
+			ExpectedBody: "An alert for **endpoint-name** has been triggered due to having failed 3 time(s) in a row:\n> description-1\n\n## Condition results\n- :white_check_mark: - `[CONNECTED] == true`\n- :x: - `[STATUS] == 200`",
+		},
+		{
+			Name:         "triggered-with-no-description",
+			Endpoint:     endpoint.Endpoint{Name: "endpoint-name", URL: "https://example.org"},
+			Provider:     AlertProvider{},
+			Alert:        alert.Alert{FailureThreshold: 10},
+			ExpectedBody: "An alert for **endpoint-name** has been triggered due to having failed 10 time(s) in a row\n\n## Condition results\n- :white_check_mark: - `[CONNECTED] == true`\n- :x: - `[STATUS] == 200`",
+		},
+		{
+			Name:         "triggered-with-no-conditions",
+			NoConditions: true,
+			Endpoint:     endpoint.Endpoint{Name: "endpoint-name", URL: "https://example.org"},
+			Provider:     AlertProvider{},
+			Alert:        alert.Alert{Description: &firstDescription, FailureThreshold: 10},
+			ExpectedBody: "An alert for **endpoint-name** has been triggered due to having failed 10 time(s) in a row:\n> description-1",
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			var conditionResults []*endpoint.ConditionResult
+			if !scenario.NoConditions {
+				conditionResults = []*endpoint.ConditionResult{
+					{Condition: "[CONNECTED] == true", Success: true},
+					{Condition: "[STATUS] == 200", Success: false},
+				}
+			}
+			body := scenario.Provider.buildIssueBody(
+				&scenario.Endpoint,
+				&scenario.Alert,
+				&endpoint.Result{ConditionResults: conditionResults},
+			)
+			if strings.TrimSpace(body) != strings.TrimSpace(scenario.ExpectedBody) {
+				t.Errorf("expected:\n%s\ngot:\n%s", scenario.ExpectedBody, body)
+			}
+		})
+	}
+}
+
+func TestAlertProvider_GetDefaultAlert(t *testing.T) {
+	if (&AlertProvider{DefaultAlert: &alert.Alert{}}).GetDefaultAlert() == nil {
+		t.Error("expected default alert to be not nil")
+	}
+	if (&AlertProvider{DefaultAlert: nil}).GetDefaultAlert() != nil {
+		t.Error("expected default alert to be nil")
+	}
+}
+
+func TestAlertProvider_GetConfig(t *testing.T) {
+	scenarios := []struct {
+		Name           string
+		Provider       AlertProvider
+		InputAlert     alert.Alert
+		ExpectedOutput Config
+	}{
+		{
+			Name: "provider-no-override-should-default",
+			Provider: AlertProvider{
+				DefaultConfig: Config{RepositoryURL: "https://github.com/TwiN/test", Token: "12345"},
+			},
+			InputAlert:     alert.Alert{},
+			ExpectedOutput: Config{RepositoryURL: "https://github.com/TwiN/test", Token: "12345"},
+		},
+		{
+			Name: "provider-with-alert-override",
+			Provider: AlertProvider{
+				DefaultConfig: Config{RepositoryURL: "https://github.com/TwiN/test", Token: "12345"},
+			},
+			InputAlert:     alert.Alert{ProviderOverride: map[string]any{"repository-url": "https://github.com/TwiN/alert-test", "token": "54321"}},
+			ExpectedOutput: Config{RepositoryURL: "https://github.com/TwiN/alert-test", Token: "54321"},
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			got, err := scenario.Provider.GetConfig("", &scenario.InputAlert)
+			if err != nil && !strings.Contains(err.Error(), "failed to retrieve GitHub user") && !strings.Contains(err.Error(), "no such host") {
+				t.Fatalf("unexpected error: %s", err)
+			}
+			if got.RepositoryURL != scenario.ExpectedOutput.RepositoryURL {
+				t.Errorf("expected repository URL %s, got %s", scenario.ExpectedOutput.RepositoryURL, got.RepositoryURL)
+			}
+			if got.Token != scenario.ExpectedOutput.Token {
+				t.Errorf("expected token %s, got %s", scenario.ExpectedOutput.Token, got.Token)
+			}
+			// Test ValidateOverrides as well, since it really just calls GetConfig
+			if err = scenario.Provider.ValidateOverrides("", &scenario.InputAlert); err != nil && !strings.Contains(err.Error(), "failed to retrieve GitHub user") {
+				t.Errorf("unexpected error: %s", err)
+			}
+		})
+	}
+}

alerting/provider/gitlab/gitlab.go

@@ -0,0 +1,204 @@
+package gitlab
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"net/url"
+	"time"
+
+	"github.com/TwiN/gatus/v5/alerting/alert"
+	"github.com/TwiN/gatus/v5/client"
+	"github.com/TwiN/gatus/v5/config/endpoint"
+	"github.com/google/uuid"
+	"gopkg.in/yaml.v3"
+)
+
+const (
+	DefaultSeverity       = "critical"
+	DefaultMonitoringTool = "gatus"
+)
+
+var (
+	ErrInvalidWebhookURL      = fmt.Errorf("invalid webhook-url")
+	ErrAuthorizationKeyNotSet = fmt.Errorf("authorization-key not set")
+)
+
+type Config struct {
+	WebhookURL       string `yaml:"webhook-url"`                // The webhook url provided by GitLab
+	AuthorizationKey string `yaml:"authorization-key"`          // The authorization key provided by GitLab
+	Severity         string `yaml:"severity,omitempty"`         // Severity can be one of: critical, high, medium, low, info, unknown. Defaults to critical
+	MonitoringTool   string `yaml:"monitoring-tool,omitempty"`  // MonitoringTool overrides the name sent to gitlab. Defaults to gatus
+	EnvironmentName  string `yaml:"environment-name,omitempty"` // EnvironmentName is the name of the associated GitLab environment. Required to display alerts on a dashboard.
+	Service          string `yaml:"service,omitempty"`          // Service affected. Defaults to the endpoint's display name
+}
+
+func (cfg *Config) Validate() error {
+	if len(cfg.WebhookURL) == 0 {
+		return ErrInvalidWebhookURL
+	} else if _, err := url.Parse(cfg.WebhookURL); err != nil {
+		return ErrInvalidWebhookURL
+	}
+	if len(cfg.AuthorizationKey) == 0 {
+		return ErrAuthorizationKeyNotSet
+	}
+	if len(cfg.Severity) == 0 {
+		cfg.Severity = DefaultSeverity
+	}
+	if len(cfg.MonitoringTool) == 0 {
+		cfg.MonitoringTool = DefaultMonitoringTool
+	}
+	return nil
+}
+
+func (cfg *Config) Merge(override *Config) {
+	if len(override.WebhookURL) > 0 {
+		cfg.WebhookURL = override.WebhookURL
+	}
+	if len(override.AuthorizationKey) > 0 {
+		cfg.AuthorizationKey = override.AuthorizationKey
+	}
+	if len(override.Severity) > 0 {
+		cfg.Severity = override.Severity
+	}
+	if len(override.MonitoringTool) > 0 {
+		cfg.MonitoringTool = override.MonitoringTool
+	}
+	if len(override.EnvironmentName) > 0 {
+		cfg.EnvironmentName = override.EnvironmentName
+	}
+	if len(override.Service) > 0 {
+		cfg.Service = override.Service
+	}
+}
+
+// AlertProvider is the configuration necessary for sending an alert using GitLab
+type AlertProvider struct {
+	DefaultConfig Config `yaml:",inline"`
+
+	// DefaultAlert is the default alert configuration to use for endpoints with an alert of the appropriate type
+	DefaultAlert *alert.Alert `yaml:"default-alert,omitempty"`
+}
+
+// Validate the provider's configuration
+func (provider *AlertProvider) Validate() error {
+	return provider.DefaultConfig.Validate()
+}
+
+// Send creates an issue in the designed RepositoryURL if the resolved parameter passed is false,
+// or closes the relevant issue(s) if the resolved parameter passed is true.
+func (provider *AlertProvider) Send(ep *endpoint.Endpoint, alert *alert.Alert, result *endpoint.Result, resolved bool) error {
+	cfg, err := provider.GetConfig(ep.Group, alert)
+	if err != nil {
+		return err
+	}
+	if len(alert.ResolveKey) == 0 {
+		alert.ResolveKey = uuid.NewString()
+	}
+	buffer := bytes.NewBuffer(provider.buildAlertBody(cfg, ep, alert, result, resolved))
+	request, err := http.NewRequest(http.MethodPost, cfg.WebhookURL, buffer)
+	if err != nil {
+		return err
+	}
+	request.Header.Set("Content-Type", "application/json")
+	request.Header.Set("Authorization", fmt.Sprintf("Bearer %s", cfg.AuthorizationKey))
+	response, err := client.GetHTTPClient(nil).Do(request)
+	if err != nil {
+		return err
+	}
+	defer response.Body.Close()
+	if response.StatusCode > 399 {
+		body, _ := io.ReadAll(response.Body)
+		return fmt.Errorf("call to provider alert returned status code %d: %s", response.StatusCode, string(body))
+	}
+	return err
+}
+
+type AlertBody struct {
+	Title                 string `json:"title,omitempty"`                   // The title of the alert.
+	Description           string `json:"description,omitempty"`             // A high-level summary of the problem.
+	StartTime             string `json:"start_time,omitempty"`              // The time of the alert. If none is provided, a current time is used.
+	EndTime               string `json:"end_time,omitempty"`                // The resolution time of the alert. If provided, the alert is resolved.
+	Service               string `json:"service,omitempty"`                 // The affected service.
+	MonitoringTool        string `json:"monitoring_tool,omitempty"`         // The name of the associated monitoring tool.
+	Hosts                 string `json:"hosts,omitempty"`                   // One or more hosts, as to where this incident occurred.
+	Severity              string `json:"severity,omitempty"`                // The severity of the alert. Case-insensitive. Can be one of: critical, high, medium, low, info, unknown. Defaults to critical if missing or value is not in this list.
+	Fingerprint           string `json:"fingerprint,omitempty"`             // The unique identifier of the alert. This can be used to group occurrences of the same alert.
+	GitlabEnvironmentName string `json:"gitlab_environment_name,omitempty"` // The name of the associated GitLab environment. Required to display alerts on a dashboard.
+}
+
+// buildAlertBody builds the body of the alert
+func (provider *AlertProvider) buildAlertBody(cfg *Config, ep *endpoint.Endpoint, alert *alert.Alert, result *endpoint.Result, resolved bool) []byte {
+	service := cfg.Service
+	if len(service) == 0 {
+		service = ep.DisplayName()
+	}
+	body := AlertBody{
+		Title:                 fmt.Sprintf("alert(%s): %s", cfg.MonitoringTool, service),
+		StartTime:             result.Timestamp.Format(time.RFC3339),
+		Service:               service,
+		MonitoringTool:        cfg.MonitoringTool,
+		Hosts:                 ep.URL,
+		GitlabEnvironmentName: cfg.EnvironmentName,
+		Severity:              cfg.Severity,
+		Fingerprint:           alert.ResolveKey,
+	}
+	if resolved {
+		body.EndTime = result.Timestamp.Format(time.RFC3339)
+	}
+	var formattedConditionResults string
+	if len(result.ConditionResults) > 0 {
+		formattedConditionResults = "\n\n## Condition results\n"
+		for _, conditionResult := range result.ConditionResults {
+			var prefix string
+			if conditionResult.Success {
+				prefix = ":white_check_mark:"
+			} else {
+				prefix = ":x:"
+			}
+			formattedConditionResults += fmt.Sprintf("- %s - `%s`\n", prefix, conditionResult.Condition)
+		}
+	}
+	var description string
+	if alertDescription := alert.GetDescription(); len(alertDescription) > 0 {
+		description = ":\n> " + alertDescription
+	}
+	var message string
+	if resolved {
+		message = fmt.Sprintf("An alert for *%s* has been resolved after passing successfully %d time(s) in a row", ep.DisplayName(), alert.SuccessThreshold)
+	} else {
+		message = fmt.Sprintf("An alert for *%s* has been triggered due to having failed %d time(s) in a row", ep.DisplayName(), alert.FailureThreshold)
+	}
+	body.Description = message + description + formattedConditionResults
+	bodyAsJSON, _ := json.Marshal(body)
+	return bodyAsJSON
+}
+
+// GetDefaultAlert returns the provider's default alert configuration
+func (provider *AlertProvider) GetDefaultAlert() *alert.Alert {
+	return provider.DefaultAlert
+}
+
+// GetConfig returns the configuration for the provider with the overrides applied
+func (provider *AlertProvider) GetConfig(group string, alert *alert.Alert) (*Config, error) {
+	cfg := provider.DefaultConfig
+	// Handle alert overrides
+	if len(alert.ProviderOverride) != 0 {
+		overrideConfig := Config{}
+		if err := yaml.Unmarshal(alert.ProviderOverrideAsBytes(), &overrideConfig); err != nil {
+			return nil, err
+		}
+		cfg.Merge(&overrideConfig)
+	}
+	// Validate the configuration (we're returning the cfg here even if there's an error mostly for testing purposes)
+	err := cfg.Validate()
+	return &cfg, err
+}
+
+// ValidateOverrides validates the alert's provider override and, if present, the group override
+func (provider *AlertProvider) ValidateOverrides(group string, alert *alert.Alert) error {
+	_, err := provider.GetConfig(group, alert)
+	return err
+}

alerting/provider/gitlab/gitlab_test.go

@@ -0,0 +1,223 @@
+package gitlab
+
+import (
+	"net/http"
+	"strings"
+	"testing"
+
+	"github.com/TwiN/gatus/v5/alerting/alert"
+	"github.com/TwiN/gatus/v5/client"
+	"github.com/TwiN/gatus/v5/config/endpoint"
+	"github.com/TwiN/gatus/v5/test"
+)
+
+func TestAlertProvider_Validate(t *testing.T) {
+	scenarios := []struct {
+		Name          string
+		Provider      AlertProvider
+		ExpectedError bool
+	}{
+		{
+			Name:          "invalid",
+			Provider:      AlertProvider{DefaultConfig: Config{WebhookURL: "", AuthorizationKey: ""}},
+			ExpectedError: true,
+		},
+		{
+			Name:          "missing-webhook-url",
+			Provider:      AlertProvider{DefaultConfig: Config{WebhookURL: "", AuthorizationKey: "12345"}},
+			ExpectedError: true,
+		},
+		{
+			Name:          "missing-authorization-key",
+			Provider:      AlertProvider{DefaultConfig: Config{WebhookURL: "https://gitlab.com/whatever/text/alerts/notify/gatus/xxxxxxxxxxxxxxxx.json", AuthorizationKey: ""}},
+			ExpectedError: true,
+		},
+		{
+			Name:          "invalid-url",
+			Provider:      AlertProvider{DefaultConfig: Config{WebhookURL: " http://foo.com", AuthorizationKey: "12345"}},
+			ExpectedError: true,
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			err := scenario.Provider.Validate()
+			if scenario.ExpectedError && err == nil {
+				t.Error("expected error, got none")
+			}
+			if !scenario.ExpectedError && err != nil && !strings.Contains(err.Error(), "user does not exist") && !strings.Contains(err.Error(), "no such host") {
+				t.Error("expected no error, got", err.Error())
+			}
+		})
+	}
+}
+
+func TestAlertProvider_Send(t *testing.T) {
+	defer client.InjectHTTPClient(nil)
+	firstDescription := "description-1"
+	secondDescription := "description-2"
+	scenarios := []struct {
+		Name             string
+		Provider         AlertProvider
+		Alert            alert.Alert
+		Resolved         bool
+		MockRoundTripper test.MockRoundTripper
+		ExpectedError    bool
+	}{
+		{
+			Name:          "triggered-error",
+			Provider:      AlertProvider{DefaultConfig: Config{WebhookURL: "https://gitlab.com/hlidotbe/text/alerts/notify/gatus/xxxxxxxxxxxxxxxx.json", AuthorizationKey: "12345"}},
+			Alert:         alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:      false,
+			ExpectedError: false,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusOK, Body: http.NoBody}
+			}),
+		},
+		{
+			Name:          "resolved-error",
+			Provider:      AlertProvider{DefaultConfig: Config{WebhookURL: "https://gitlab.com/hlidotbe/text/alerts/notify/gatus/xxxxxxxxxxxxxxxx.json", AuthorizationKey: "12345"}},
+			Alert:         alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:      true,
+			ExpectedError: false,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusOK, Body: http.NoBody}
+			}),
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			client.InjectHTTPClient(&http.Client{Transport: scenario.MockRoundTripper})
+			err := scenario.Provider.Send(
+				&endpoint.Endpoint{Name: "endpoint-name", Group: "endpoint-group"},
+				&scenario.Alert,
+				&endpoint.Result{
+					ConditionResults: []*endpoint.ConditionResult{
+						{Condition: "[CONNECTED] == true", Success: scenario.Resolved},
+						{Condition: "[STATUS] == 200", Success: scenario.Resolved},
+					},
+				},
+				scenario.Resolved,
+			)
+			if scenario.ExpectedError && err == nil {
+				t.Error("expected error, got none")
+			}
+			if !scenario.ExpectedError && err != nil {
+				t.Error("expected no error, got", err.Error())
+			}
+		})
+	}
+}
+
+func TestAlertProvider_buildAlertBody(t *testing.T) {
+	firstDescription := "description-1"
+	scenarios := []struct {
+		Name         string
+		Endpoint     endpoint.Endpoint
+		Provider     AlertProvider
+		Alert        alert.Alert
+		ExpectedBody string
+	}{
+		{
+			Name:         "triggered",
+			Endpoint:     endpoint.Endpoint{Name: "endpoint-name", URL: "https://example.org"},
+			Provider:     AlertProvider{DefaultConfig: Config{WebhookURL: "https://gitlab.com/hlidotbe/text/alerts/notify/gatus/xxxxxxxxxxxxxxxx.json", AuthorizationKey: "12345"}},
+			Alert:        alert.Alert{Description: &firstDescription, FailureThreshold: 3},
+			ExpectedBody: "{\"title\":\"alert(gatus): endpoint-name\",\"description\":\"An alert for *endpoint-name* has been triggered due to having failed 3 time(s) in a row:\\n\\u003e description-1\\n\\n## Condition results\\n- :white_check_mark: - `[CONNECTED] == true`\\n- :x: - `[STATUS] == 200`\\n\",\"start_time\":\"0001-01-01T00:00:00Z\",\"service\":\"endpoint-name\",\"monitoring_tool\":\"gatus\",\"hosts\":\"https://example.org\",\"severity\":\"critical\"}",
+		},
+		{
+			Name:         "no-description",
+			Endpoint:     endpoint.Endpoint{Name: "endpoint-name", URL: "https://example.org"},
+			Provider:     AlertProvider{DefaultConfig: Config{WebhookURL: "https://gitlab.com/hlidotbe/text/alerts/notify/gatus/xxxxxxxxxxxxxxxx.json", AuthorizationKey: "12345"}},
+			Alert:        alert.Alert{FailureThreshold: 10},
+			ExpectedBody: "{\"title\":\"alert(gatus): endpoint-name\",\"description\":\"An alert for *endpoint-name* has been triggered due to having failed 10 time(s) in a row\\n\\n## Condition results\\n- :white_check_mark: - `[CONNECTED] == true`\\n- :x: - `[STATUS] == 200`\\n\",\"start_time\":\"0001-01-01T00:00:00Z\",\"service\":\"endpoint-name\",\"monitoring_tool\":\"gatus\",\"hosts\":\"https://example.org\",\"severity\":\"critical\"}",
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			cfg, err := scenario.Provider.GetConfig("", &scenario.Alert)
+			if err != nil {
+				t.Error("expected no error, got", err.Error())
+			}
+			body := scenario.Provider.buildAlertBody(
+				cfg,
+				&scenario.Endpoint,
+				&scenario.Alert,
+				&endpoint.Result{
+					ConditionResults: []*endpoint.ConditionResult{
+						{Condition: "[CONNECTED] == true", Success: true},
+						{Condition: "[STATUS] == 200", Success: false},
+					},
+				},
+				false,
+			)
+			if strings.TrimSpace(string(body)) != strings.TrimSpace(scenario.ExpectedBody) {
+				t.Errorf("expected:\n%s\ngot:\n%s", scenario.ExpectedBody, body)
+			}
+		})
+	}
+}
+
+func TestAlertProvider_GetDefaultAlert(t *testing.T) {
+	if (&AlertProvider{DefaultAlert: &alert.Alert{}}).GetDefaultAlert() == nil {
+		t.Error("expected default alert to be not nil")
+	}
+	if (&AlertProvider{DefaultAlert: nil}).GetDefaultAlert() != nil {
+		t.Error("expected default alert to be nil")
+	}
+}
+
+func TestAlertProvider_GetConfig(t *testing.T) {
+	scenarios := []struct {
+		Name           string
+		Provider       AlertProvider
+		InputAlert     alert.Alert
+		ExpectedOutput Config
+	}{
+		{
+			Name: "provider-no-override-should-default",
+			Provider: AlertProvider{
+				DefaultConfig: Config{WebhookURL: "https://github.com/TwiN/test", AuthorizationKey: "12345"},
+			},
+			InputAlert:     alert.Alert{},
+			ExpectedOutput: Config{WebhookURL: "https://github.com/TwiN/test", AuthorizationKey: "12345", Severity: DefaultSeverity, MonitoringTool: DefaultMonitoringTool},
+		},
+		{
+			Name: "provider-with-alert-override",
+			Provider: AlertProvider{
+				DefaultConfig: Config{WebhookURL: "https://github.com/TwiN/test", AuthorizationKey: "12345"},
+			},
+			InputAlert:     alert.Alert{ProviderOverride: map[string]any{"repository-url": "https://github.com/TwiN/alert-test", "authorization-key": "54321", "severity": "info", "monitoring-tool": "not-gatus", "environment-name": "prod", "service": "example"}},
+			ExpectedOutput: Config{WebhookURL: "https://github.com/TwiN/test", AuthorizationKey: "54321", Severity: "info", MonitoringTool: "not-gatus", EnvironmentName: "prod", Service: "example"},
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			got, err := scenario.Provider.GetConfig("", &scenario.InputAlert)
+			if err != nil && !strings.Contains(err.Error(), "user does not exist") && !strings.Contains(err.Error(), "no such host") {
+				t.Fatalf("unexpected error: %s", err)
+			}
+			if got.WebhookURL != scenario.ExpectedOutput.WebhookURL {
+				t.Errorf("expected repository URL %s, got %s", scenario.ExpectedOutput.WebhookURL, got.WebhookURL)
+			}
+			if got.AuthorizationKey != scenario.ExpectedOutput.AuthorizationKey {
+				t.Errorf("expected AuthorizationKey %s, got %s", scenario.ExpectedOutput.AuthorizationKey, got.AuthorizationKey)
+			}
+			if got.Severity != scenario.ExpectedOutput.Severity {
+				t.Errorf("expected Severity %s, got %s", scenario.ExpectedOutput.Severity, got.Severity)
+			}
+			if got.MonitoringTool != scenario.ExpectedOutput.MonitoringTool {
+				t.Errorf("expected MonitoringTool %s, got %s", scenario.ExpectedOutput.MonitoringTool, got.MonitoringTool)
+			}
+			if got.EnvironmentName != scenario.ExpectedOutput.EnvironmentName {
+				t.Errorf("expected EnvironmentName %s, got %s", scenario.ExpectedOutput.EnvironmentName, got.EnvironmentName)
+			}
+			if got.Service != scenario.ExpectedOutput.Service {
+				t.Errorf("expected Service %s, got %s", scenario.ExpectedOutput.Service, got.Service)
+			}
+			// Test ValidateOverrides as well, since it really just calls GetConfig
+			if err = scenario.Provider.ValidateOverrides("", &scenario.InputAlert); err != nil {
+				t.Errorf("unexpected error: %s", err)
+			}
+		})
+	}
+}

alerting/provider/googlechat/googlechat.go

@@ -0,0 +1,248 @@
+package googlechat
+
+import (
+	"bytes"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+
+	"github.com/TwiN/gatus/v5/alerting/alert"
+	"github.com/TwiN/gatus/v5/client"
+	"github.com/TwiN/gatus/v5/config/endpoint"
+	"gopkg.in/yaml.v3"
+)
+
+var (
+	ErrWebhookURLNotSet       = errors.New("webhook-url not set")
+	ErrDuplicateGroupOverride = errors.New("duplicate group override")
+)
+
+type Config struct {
+	WebhookURL   string         `yaml:"webhook-url"`
+	ClientConfig *client.Config `yaml:"client,omitempty"`
+}
+
+func (cfg *Config) Validate() error {
+	if len(cfg.WebhookURL) == 0 {
+		return ErrWebhookURLNotSet
+	}
+	return nil
+}
+
+func (cfg *Config) Merge(override *Config) {
+	if override.ClientConfig != nil {
+		cfg.ClientConfig = override.ClientConfig
+	}
+	if len(override.WebhookURL) > 0 {
+		cfg.WebhookURL = override.WebhookURL
+	}
+}
+
+// AlertProvider is the configuration necessary for sending an alert using Google chat
+type AlertProvider struct {
+	DefaultConfig Config `yaml:",inline"`
+
+	// DefaultAlert is the default alert configuration to use for endpoints with an alert of the appropriate type
+	DefaultAlert *alert.Alert `yaml:"default-alert,omitempty"`
+
+	// Overrides is a list of Override that may be prioritized over the default configuration
+	Overrides []Override `yaml:"overrides,omitempty"`
+}
+
+// Override is a case under which the default integration is overridden
+type Override struct {
+	Group  string `yaml:"group"`
+	Config `yaml:",inline"`
+}
+
+// Validate the provider's configuration
+func (provider *AlertProvider) Validate() error {
+	registeredGroups := make(map[string]bool)
+	if provider.Overrides != nil {
+		for _, override := range provider.Overrides {
+			if isAlreadyRegistered := registeredGroups[override.Group]; isAlreadyRegistered || override.Group == "" || len(override.WebhookURL) == 0 {
+				return ErrDuplicateGroupOverride
+			}
+			registeredGroups[override.Group] = true
+		}
+	}
+	return provider.DefaultConfig.Validate()
+}
+
+// Send an alert using the provider
+func (provider *AlertProvider) Send(ep *endpoint.Endpoint, alert *alert.Alert, result *endpoint.Result, resolved bool) error {
+	cfg, err := provider.GetConfig(ep.Group, alert)
+	if err != nil {
+		return err
+	}
+	buffer := bytes.NewBuffer(provider.buildRequestBody(ep, alert, result, resolved))
+	request, err := http.NewRequest(http.MethodPost, cfg.WebhookURL, buffer)
+	if err != nil {
+		return err
+	}
+	request.Header.Set("Content-Type", "application/json")
+	response, err := client.GetHTTPClient(cfg.ClientConfig).Do(request)
+	if err != nil {
+		return err
+	}
+	defer response.Body.Close()
+	if response.StatusCode > 399 {
+		body, _ := io.ReadAll(response.Body)
+		return fmt.Errorf("call to provider alert returned status code %d: %s", response.StatusCode, string(body))
+	}
+	return err
+}
+
+type Body struct {
+	Cards []Cards `json:"cards"`
+}
+
+type Cards struct {
+	Sections []Sections `json:"sections"`
+}
+
+type Sections struct {
+	Widgets []Widgets `json:"widgets"`
+}
+
+type Widgets struct {
+	KeyValue *KeyValue `json:"keyValue,omitempty"`
+	Buttons  []Buttons `json:"buttons,omitempty"`
+}
+
+type KeyValue struct {
+	TopLabel         string `json:"topLabel,omitempty"`
+	Content          string `json:"content,omitempty"`
+	ContentMultiline string `json:"contentMultiline,omitempty"`
+	BottomLabel      string `json:"bottomLabel,omitempty"`
+	Icon             string `json:"icon,omitempty"`
+}
+
+type Buttons struct {
+	TextButton TextButton `json:"textButton"`
+}
+
+type TextButton struct {
+	Text    string  `json:"text"`
+	OnClick OnClick `json:"onClick"`
+}
+
+type OnClick struct {
+	OpenLink OpenLink `json:"openLink"`
+}
+
+type OpenLink struct {
+	URL string `json:"url"`
+}
+
+// buildRequestBody builds the request body for the provider
+func (provider *AlertProvider) buildRequestBody(ep *endpoint.Endpoint, alert *alert.Alert, result *endpoint.Result, resolved bool) []byte {
+	var message, color string
+	if resolved {
+		color = "#36A64F"
+		message = fmt.Sprintf("<font color='%s'>An alert has been resolved after passing successfully %d time(s) in a row</font>", color, alert.SuccessThreshold)
+	} else {
+		color = "#DD0000"
+		message = fmt.Sprintf("<font color='%s'>An alert has been triggered due to having failed %d time(s) in a row</font>", color, alert.FailureThreshold)
+	}
+	var formattedConditionResults string
+	for _, conditionResult := range result.ConditionResults {
+		var prefix string
+		if conditionResult.Success {
+			prefix = "✅"
+		} else {
+			prefix = "❌"
+		}
+		formattedConditionResults += fmt.Sprintf("%s   %s<br>", prefix, conditionResult.Condition)
+	}
+	var description string
+	if alertDescription := alert.GetDescription(); len(alertDescription) > 0 {
+		description = ":: " + alertDescription
+	}
+	payload := Body{
+		Cards: []Cards{
+			{
+				Sections: []Sections{
+					{
+						Widgets: []Widgets{
+							{
+								KeyValue: &KeyValue{
+									TopLabel:         ep.DisplayName(),
+									Content:          message,
+									ContentMultiline: "true",
+									BottomLabel:      description,
+									Icon:             "BOOKMARK",
+								},
+							},
+						},
+					},
+				},
+			},
+		},
+	}
+	if len(formattedConditionResults) > 0 {
+		payload.Cards[0].Sections[0].Widgets = append(payload.Cards[0].Sections[0].Widgets, Widgets{
+			KeyValue: &KeyValue{
+				TopLabel:         "Condition results",
+				Content:          formattedConditionResults,
+				ContentMultiline: "true",
+				Icon:             "DESCRIPTION",
+			},
+		})
+	}
+	if ep.Type() == endpoint.TypeHTTP {
+		// We only include a button targeting the URL if the endpoint is an HTTP endpoint
+		// If the URL isn't prefixed with https://, Google Chat will just display a blank message aynways.
+		// See https://github.com/TwiN/gatus/issues/362
+		payload.Cards[0].Sections[0].Widgets = append(payload.Cards[0].Sections[0].Widgets, Widgets{
+			Buttons: []Buttons{
+				{
+					TextButton: TextButton{
+						Text:    "URL",
+						OnClick: OnClick{OpenLink: OpenLink{URL: ep.URL}},
+					},
+				},
+			},
+		})
+	}
+	bodyAsJSON, _ := json.Marshal(payload)
+	return bodyAsJSON
+}
+
+// GetDefaultAlert returns the provider's default alert configuration
+func (provider *AlertProvider) GetDefaultAlert() *alert.Alert {
+	return provider.DefaultAlert
+}
+
+// GetConfig returns the configuration for the provider with the overrides applied
+func (provider *AlertProvider) GetConfig(group string, alert *alert.Alert) (*Config, error) {
+	cfg := provider.DefaultConfig
+	// Handle group overrides
+	if provider.Overrides != nil {
+		for _, override := range provider.Overrides {
+			if group == override.Group {
+				cfg.Merge(&override.Config)
+				break
+			}
+		}
+	}
+	// Handle alert overrides
+	if len(alert.ProviderOverride) != 0 {
+		overrideConfig := Config{}
+		if err := yaml.Unmarshal(alert.ProviderOverrideAsBytes(), &overrideConfig); err != nil {
+			return nil, err
+		}
+		cfg.Merge(&overrideConfig)
+	}
+	// Validate the configuration
+	err := cfg.Validate()
+	return &cfg, err
+}
+
+// ValidateOverrides validates the alert's provider override and, if present, the group override
+func (provider *AlertProvider) ValidateOverrides(group string, alert *alert.Alert) error {
+	_, err := provider.GetConfig(group, alert)
+	return err
+}

alerting/provider/googlechat/googlechat_test.go

@@ -0,0 +1,305 @@
+package googlechat
+
+import (
+	"encoding/json"
+	"net/http"
+	"testing"
+
+	"github.com/TwiN/gatus/v5/alerting/alert"
+	"github.com/TwiN/gatus/v5/client"
+	"github.com/TwiN/gatus/v5/config/endpoint"
+	"github.com/TwiN/gatus/v5/test"
+)
+
+func TestAlertProvider_Validate(t *testing.T) {
+	invalidProvider := AlertProvider{DefaultConfig: Config{WebhookURL: ""}}
+	if err := invalidProvider.Validate(); err == nil {
+		t.Error("provider shouldn't have been valid")
+	}
+	validProvider := AlertProvider{DefaultConfig: Config{WebhookURL: "http://example.com"}}
+	if err := validProvider.Validate(); err != nil {
+		t.Error("provider should've been valid")
+	}
+}
+
+func TestAlertProvider_ValidateWithOverride(t *testing.T) {
+	providerWithInvalidOverrideGroup := AlertProvider{
+		Overrides: []Override{
+			{
+				Config: Config{WebhookURL: "http://example.com"},
+				Group:  "",
+			},
+		},
+	}
+	if err := providerWithInvalidOverrideGroup.Validate(); err == nil {
+		t.Error("provider Group shouldn't have been valid")
+	}
+	providerWithInvalidOverrideTo := AlertProvider{
+		Overrides: []Override{
+			{
+				Config: Config{WebhookURL: ""},
+				Group:  "group",
+			},
+		},
+	}
+	if err := providerWithInvalidOverrideTo.Validate(); err == nil {
+		t.Error("provider integration key shouldn't have been valid")
+	}
+	providerWithValidOverride := AlertProvider{
+		DefaultConfig: Config{WebhookURL: "http://example.com"},
+		Overrides: []Override{
+			{
+				Config: Config{WebhookURL: "http://example.com"},
+				Group:  "group",
+			},
+		},
+	}
+	if err := providerWithValidOverride.Validate(); err != nil {
+		t.Error("provider should've been valid")
+	}
+}
+
+func TestAlertProvider_Send(t *testing.T) {
+	defer client.InjectHTTPClient(nil)
+	firstDescription := "description-1"
+	secondDescription := "description-2"
+	scenarios := []struct {
+		Name             string
+		Provider         AlertProvider
+		Alert            alert.Alert
+		Resolved         bool
+		MockRoundTripper test.MockRoundTripper
+		ExpectedError    bool
+	}{
+		{
+			Name:     "triggered",
+			Provider: AlertProvider{DefaultConfig: Config{WebhookURL: "http://example.com"}},
+			Alert:    alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: false,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusOK, Body: http.NoBody}
+			}),
+			ExpectedError: false,
+		},
+		{
+			Name:     "triggered-error",
+			Provider: AlertProvider{DefaultConfig: Config{WebhookURL: "http://example.com"}},
+			Alert:    alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: false,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusInternalServerError, Body: http.NoBody}
+			}),
+			ExpectedError: true,
+		},
+		{
+			Name:     "resolved",
+			Provider: AlertProvider{DefaultConfig: Config{WebhookURL: "http://example.com"}},
+			Alert:    alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: true,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusOK, Body: http.NoBody}
+			}),
+			ExpectedError: false,
+		},
+		{
+			Name:     "resolved-error",
+			Provider: AlertProvider{DefaultConfig: Config{WebhookURL: "http://example.com"}},
+			Alert:    alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: true,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusInternalServerError, Body: http.NoBody}
+			}),
+			ExpectedError: true,
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			client.InjectHTTPClient(&http.Client{Transport: scenario.MockRoundTripper})
+			err := scenario.Provider.Send(
+				&endpoint.Endpoint{Name: "endpoint-name", Group: "endpoint-group"},
+				&scenario.Alert,
+				&endpoint.Result{
+					ConditionResults: []*endpoint.ConditionResult{
+						{Condition: "[CONNECTED] == true", Success: scenario.Resolved},
+						{Condition: "[STATUS] == 200", Success: scenario.Resolved},
+					},
+				},
+				scenario.Resolved,
+			)
+			if scenario.ExpectedError && err == nil {
+				t.Error("expected error, got none")
+			}
+			if !scenario.ExpectedError && err != nil {
+				t.Error("expected no error, got", err.Error())
+			}
+		})
+	}
+}
+
+func TestAlertProvider_buildRequestBody(t *testing.T) {
+	firstDescription := "description-1"
+	secondDescription := "description-2"
+	scenarios := []struct {
+		Name         string
+		Endpoint     endpoint.Endpoint
+		Provider     AlertProvider
+		Alert        alert.Alert
+		Resolved     bool
+		ExpectedBody string
+	}{
+		{
+			Name:         "triggered",
+			Endpoint:     endpoint.Endpoint{Name: "endpoint-name", URL: "https://example.org"},
+			Provider:     AlertProvider{},
+			Alert:        alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     false,
+			ExpectedBody: `{"cards":[{"sections":[{"widgets":[{"keyValue":{"topLabel":"endpoint-name","content":"\u003cfont color='#DD0000'\u003eAn alert has been triggered due to having failed 3 time(s) in a row\u003c/font\u003e","contentMultiline":"true","bottomLabel":":: description-1","icon":"BOOKMARK"}},{"keyValue":{"topLabel":"Condition results","content":"❌   [CONNECTED] == true\u003cbr\u003e❌   [STATUS] == 200\u003cbr\u003e","contentMultiline":"true","icon":"DESCRIPTION"}},{"buttons":[{"textButton":{"text":"URL","onClick":{"openLink":{"url":"https://example.org"}}}}]}]}]}]}`,
+		},
+		{
+			Name:         "resolved",
+			Endpoint:     endpoint.Endpoint{Name: "endpoint-name", URL: "https://example.org"},
+			Provider:     AlertProvider{},
+			Alert:        alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     true,
+			ExpectedBody: `{"cards":[{"sections":[{"widgets":[{"keyValue":{"topLabel":"endpoint-name","content":"\u003cfont color='#36A64F'\u003eAn alert has been resolved after passing successfully 5 time(s) in a row\u003c/font\u003e","contentMultiline":"true","bottomLabel":":: description-2","icon":"BOOKMARK"}},{"keyValue":{"topLabel":"Condition results","content":"✅   [CONNECTED] == true\u003cbr\u003e✅   [STATUS] == 200\u003cbr\u003e","contentMultiline":"true","icon":"DESCRIPTION"}},{"buttons":[{"textButton":{"text":"URL","onClick":{"openLink":{"url":"https://example.org"}}}}]}]}]}]}`,
+		},
+		{
+			Name:         "icmp-should-not-include-url", // See https://github.com/TwiN/gatus/issues/362
+			Endpoint:     endpoint.Endpoint{Name: "endpoint-name", URL: "icmp://example.org"},
+			Provider:     AlertProvider{},
+			Alert:        alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     false,
+			ExpectedBody: `{"cards":[{"sections":[{"widgets":[{"keyValue":{"topLabel":"endpoint-name","content":"\u003cfont color='#DD0000'\u003eAn alert has been triggered due to having failed 3 time(s) in a row\u003c/font\u003e","contentMultiline":"true","bottomLabel":":: description-1","icon":"BOOKMARK"}},{"keyValue":{"topLabel":"Condition results","content":"❌   [CONNECTED] == true\u003cbr\u003e❌   [STATUS] == 200\u003cbr\u003e","contentMultiline":"true","icon":"DESCRIPTION"}}]}]}]}`,
+		},
+		{
+			Name:         "tcp-should-not-include-url", // See https://github.com/TwiN/gatus/issues/362
+			Endpoint:     endpoint.Endpoint{Name: "endpoint-name", URL: "tcp://example.org"},
+			Provider:     AlertProvider{},
+			Alert:        alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     false,
+			ExpectedBody: `{"cards":[{"sections":[{"widgets":[{"keyValue":{"topLabel":"endpoint-name","content":"\u003cfont color='#DD0000'\u003eAn alert has been triggered due to having failed 3 time(s) in a row\u003c/font\u003e","contentMultiline":"true","bottomLabel":":: description-1","icon":"BOOKMARK"}},{"keyValue":{"topLabel":"Condition results","content":"❌   [CONNECTED] == true\u003cbr\u003e❌   [STATUS] == 200\u003cbr\u003e","contentMultiline":"true","icon":"DESCRIPTION"}}]}]}]}`,
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			body := scenario.Provider.buildRequestBody(
+				&scenario.Endpoint,
+				&scenario.Alert,
+				&endpoint.Result{
+					ConditionResults: []*endpoint.ConditionResult{
+						{Condition: "[CONNECTED] == true", Success: scenario.Resolved},
+						{Condition: "[STATUS] == 200", Success: scenario.Resolved},
+					},
+				},
+				scenario.Resolved,
+			)
+			if string(body) != scenario.ExpectedBody {
+				t.Errorf("expected:\n%s\ngot:\n%s", scenario.ExpectedBody, body)
+			}
+			out := make(map[string]interface{})
+			if err := json.Unmarshal(body, &out); err != nil {
+				t.Error("expected body to be valid JSON, got error:", err.Error())
+			}
+		})
+	}
+}
+
+func TestAlertProvider_GetDefaultAlert(t *testing.T) {
+	if (&AlertProvider{DefaultAlert: &alert.Alert{}}).GetDefaultAlert() == nil {
+		t.Error("expected default alert to be not nil")
+	}
+	if (&AlertProvider{DefaultAlert: nil}).GetDefaultAlert() != nil {
+		t.Error("expected default alert to be nil")
+	}
+}
+
+func TestAlertProvider_GetConfig(t *testing.T) {
+	scenarios := []struct {
+		Name           string
+		Provider       AlertProvider
+		InputGroup     string
+		InputAlert     alert.Alert
+		ExpectedOutput Config
+	}{
+		{
+			Name: "provider-no-override-specify-no-group-should-default",
+			Provider: AlertProvider{
+				DefaultConfig: Config{WebhookURL: "http://example.com"},
+				Overrides:     nil,
+			},
+			InputGroup:     "",
+			InputAlert:     alert.Alert{},
+			ExpectedOutput: Config{WebhookURL: "http://example.com"},
+		},
+		{
+			Name: "provider-no-override-specify-group-should-default",
+			Provider: AlertProvider{
+				DefaultConfig: Config{WebhookURL: "http://example.com"},
+				Overrides:     nil,
+			},
+			InputGroup:     "group",
+			InputAlert:     alert.Alert{},
+			ExpectedOutput: Config{WebhookURL: "http://example.com"},
+		},
+		{
+			Name: "provider-with-override-specify-no-group-should-default",
+			Provider: AlertProvider{
+				DefaultConfig: Config{WebhookURL: "http://example.com"},
+				Overrides: []Override{
+					{
+						Group:  "group",
+						Config: Config{WebhookURL: "http://example01.com"},
+					},
+				},
+			},
+			InputGroup:     "",
+			InputAlert:     alert.Alert{},
+			ExpectedOutput: Config{WebhookURL: "http://example.com"},
+		},
+		{
+			Name: "provider-with-override-specify-group-should-override",
+			Provider: AlertProvider{
+				DefaultConfig: Config{WebhookURL: "http://example.com"},
+				Overrides: []Override{
+					{
+						Group:  "group",
+						Config: Config{WebhookURL: "http://group-example.com"},
+					},
+				},
+			},
+			InputGroup:     "group",
+			InputAlert:     alert.Alert{},
+			ExpectedOutput: Config{WebhookURL: "http://group-example.com"},
+		},
+		{
+			Name: "provider-with-group-override-and-alert-override--alert-override-should-take-precedence",
+			Provider: AlertProvider{
+				DefaultConfig: Config{WebhookURL: "http://example.com"},
+				Overrides: []Override{
+					{
+						Group:  "group",
+						Config: Config{WebhookURL: "http://group-example.com"},
+					},
+				},
+			},
+			InputGroup:     "group",
+			InputAlert:     alert.Alert{ProviderOverride: map[string]any{"webhook-url": "http://alert-example.com"}},
+			ExpectedOutput: Config{WebhookURL: "http://alert-example.com"},
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			got, err := scenario.Provider.GetConfig(scenario.InputGroup, &scenario.InputAlert)
+			if err != nil {
+				t.Fatalf("unexpected error: %s", err)
+			}
+			if got.WebhookURL != scenario.ExpectedOutput.WebhookURL {
+				t.Errorf("expected webhook URL to be %s, got %s", scenario.ExpectedOutput.WebhookURL, got.WebhookURL)
+			}
+			// Test ValidateOverrides as well, since it really just calls GetConfig
+			if err = scenario.Provider.ValidateOverrides(scenario.InputGroup, &scenario.InputAlert); err != nil {
+				t.Errorf("unexpected error: %s", err)
+			}
+		})
+	}
+}

alerting/provider/gotify/gotify.go

@@ -0,0 +1,161 @@
+package gotify
+
+import (
+	"bytes"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+
+	"github.com/TwiN/gatus/v5/alerting/alert"
+	"github.com/TwiN/gatus/v5/client"
+	"github.com/TwiN/gatus/v5/config/endpoint"
+	"gopkg.in/yaml.v3"
+)
+
+const DefaultPriority = 5
+
+var (
+	ErrServerURLNotSet = errors.New("server URL not set")
+	ErrTokenNotSet     = errors.New("token not set")
+)
+
+type Config struct {
+	ServerURL string `yaml:"server-url"`         // URL of the Gotify server
+	Token     string `yaml:"token"`              // Token to use when sending a message to the Gotify server
+	Priority  int    `yaml:"priority,omitempty"` // Priority of the message. Defaults to DefaultPriority.
+	Title     string `yaml:"title,omitempty"`    // Title of the message that will be sent
+}
+
+func (cfg *Config) Validate() error {
+	if cfg.Priority == 0 {
+		cfg.Priority = DefaultPriority
+	}
+	if len(cfg.ServerURL) == 0 {
+		return ErrServerURLNotSet
+	}
+	if len(cfg.Token) == 0 {
+		return ErrTokenNotSet
+	}
+	return nil
+}
+
+func (cfg *Config) Merge(override *Config) {
+	if len(override.ServerURL) > 0 {
+		cfg.ServerURL = override.ServerURL
+	}
+	if len(override.Token) > 0 {
+		cfg.Token = override.Token
+	}
+	if override.Priority != 0 {
+		cfg.Priority = override.Priority
+	}
+	if len(override.Title) > 0 {
+		cfg.Title = override.Title
+	}
+}
+
+// AlertProvider is the configuration necessary for sending an alert using Gotify
+type AlertProvider struct {
+	DefaultConfig Config `yaml:",inline"`
+
+	// DefaultAlert is the default alert configuration to use for endpoints with an alert of the appropriate type
+	DefaultAlert *alert.Alert `yaml:"default-alert,omitempty"`
+}
+
+// Validate the provider's configuration
+func (provider *AlertProvider) Validate() error {
+	return provider.DefaultConfig.Validate()
+}
+
+// Send an alert using the provider
+func (provider *AlertProvider) Send(ep *endpoint.Endpoint, alert *alert.Alert, result *endpoint.Result, resolved bool) error {
+	cfg, err := provider.GetConfig(ep.Group, alert)
+	if err != nil {
+		return err
+	}
+	buffer := bytes.NewBuffer(provider.buildRequestBody(cfg, ep, alert, result, resolved))
+	request, err := http.NewRequest(http.MethodPost, cfg.ServerURL+"/message?token="+cfg.Token, buffer)
+	if err != nil {
+		return err
+	}
+	request.Header.Set("Content-Type", "application/json")
+	response, err := client.GetHTTPClient(nil).Do(request)
+	if err != nil {
+		return err
+	}
+	defer response.Body.Close()
+	if response.StatusCode > 399 {
+		body, _ := io.ReadAll(response.Body)
+		return fmt.Errorf("failed to send alert to Gotify: %s", string(body))
+	}
+	return nil
+}
+
+type Body struct {
+	Message  string `json:"message"`
+	Title    string `json:"title"`
+	Priority int    `json:"priority"`
+}
+
+// buildRequestBody builds the request body for the provider
+func (provider *AlertProvider) buildRequestBody(cfg *Config, ep *endpoint.Endpoint, alert *alert.Alert, result *endpoint.Result, resolved bool) []byte {
+	var message string
+	if resolved {
+		message = fmt.Sprintf("An alert for `%s` has been resolved after passing successfully %d time(s) in a row", ep.DisplayName(), alert.SuccessThreshold)
+	} else {
+		message = fmt.Sprintf("An alert for `%s` has been triggered due to having failed %d time(s) in a row", ep.DisplayName(), alert.FailureThreshold)
+	}
+	var formattedConditionResults string
+	for _, conditionResult := range result.ConditionResults {
+		var prefix string
+		if conditionResult.Success {
+			prefix = "✓"
+		} else {
+			prefix = "✕"
+		}
+		formattedConditionResults += fmt.Sprintf("\n%s - %s", prefix, conditionResult.Condition)
+	}
+	if len(alert.GetDescription()) > 0 {
+		message += " with the following description: " + alert.GetDescription()
+	}
+	message += formattedConditionResults
+	title := "Gatus: " + ep.DisplayName()
+	if cfg.Title != "" {
+		title = cfg.Title
+	}
+	bodyAsJSON, _ := json.Marshal(Body{
+		Message:  message,
+		Title:    title,
+		Priority: cfg.Priority,
+	})
+	return bodyAsJSON
+}
+
+// GetDefaultAlert returns the provider's default alert configuration
+func (provider *AlertProvider) GetDefaultAlert() *alert.Alert {
+	return provider.DefaultAlert
+}
+
+// GetConfig returns the configuration for the provider with the overrides applied
+func (provider *AlertProvider) GetConfig(group string, alert *alert.Alert) (*Config, error) {
+	cfg := provider.DefaultConfig
+	// Handle alert overrides
+	if len(alert.ProviderOverride) != 0 {
+		overrideConfig := Config{}
+		if err := yaml.Unmarshal(alert.ProviderOverrideAsBytes(), &overrideConfig); err != nil {
+			return nil, err
+		}
+		cfg.Merge(&overrideConfig)
+	}
+	// Validate the configuration
+	err := cfg.Validate()
+	return &cfg, err
+}
+
+// ValidateOverrides validates the alert's provider override and, if present, the group override
+func (provider *AlertProvider) ValidateOverrides(group string, alert *alert.Alert) error {
+	_, err := provider.GetConfig(group, alert)
+	return err
+}

alerting/provider/gotify/gotify_test.go

@@ -0,0 +1,163 @@
+package gotify
+
+import (
+	"encoding/json"
+	"fmt"
+	"testing"
+
+	"github.com/TwiN/gatus/v5/alerting/alert"
+	"github.com/TwiN/gatus/v5/config/endpoint"
+)
+
+func TestAlertProvider_Validate(t *testing.T) {
+	scenarios := []struct {
+		name     string
+		provider AlertProvider
+		expected bool
+	}{
+		{
+			name:     "valid",
+			provider: AlertProvider{DefaultConfig: Config{ServerURL: "https://gotify.example.com", Token: "faketoken"}},
+			expected: true,
+		},
+		{
+			name:     "invalid-server-url",
+			provider: AlertProvider{DefaultConfig: Config{ServerURL: "", Token: "faketoken"}},
+			expected: false,
+		},
+		{
+			name:     "invalid-app-token",
+			provider: AlertProvider{DefaultConfig: Config{ServerURL: "https://gotify.example.com", Token: ""}},
+			expected: false,
+		},
+		{
+			name:     "no-priority-should-use-default-value",
+			provider: AlertProvider{DefaultConfig: Config{ServerURL: "https://gotify.example.com", Token: "faketoken"}},
+			expected: true,
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.name, func(t *testing.T) {
+			if err := scenario.provider.Validate(); (err == nil) != scenario.expected {
+				t.Errorf("expected: %t, got: %t", scenario.expected, err == nil)
+			}
+		})
+	}
+}
+
+func TestAlertProvider_buildRequestBody(t *testing.T) {
+	var (
+		description = "custom-description"
+		//title       = "custom-title"
+		endpointName = "custom-endpoint"
+	)
+	scenarios := []struct {
+		Name         string
+		Provider     AlertProvider
+		Alert        alert.Alert
+		Resolved     bool
+		ExpectedBody string
+	}{
+		{
+			Name:         "triggered",
+			Provider:     AlertProvider{DefaultConfig: Config{ServerURL: "https://gotify.example.com", Token: "faketoken"}},
+			Alert:        alert.Alert{Description: &description, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     false,
+			ExpectedBody: fmt.Sprintf("{\"message\":\"An alert for `%s` has been triggered due to having failed 3 time(s) in a row with the following description: %s\\n✕ - [CONNECTED] == true\\n✕ - [STATUS] == 200\",\"title\":\"Gatus: custom-endpoint\",\"priority\":0}", endpointName, description),
+		},
+		{
+			Name:         "resolved",
+			Provider:     AlertProvider{DefaultConfig: Config{ServerURL: "https://gotify.example.com", Token: "faketoken"}},
+			Alert:        alert.Alert{Description: &description, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     true,
+			ExpectedBody: fmt.Sprintf("{\"message\":\"An alert for `%s` has been resolved after passing successfully 5 time(s) in a row with the following description: %s\\n✓ - [CONNECTED] == true\\n✓ - [STATUS] == 200\",\"title\":\"Gatus: custom-endpoint\",\"priority\":0}", endpointName, description),
+		},
+		{
+			Name:         "custom-title",
+			Provider:     AlertProvider{DefaultConfig: Config{ServerURL: "https://gotify.example.com", Token: "faketoken", Title: "custom-title"}},
+			Alert:        alert.Alert{Description: &description, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     false,
+			ExpectedBody: fmt.Sprintf("{\"message\":\"An alert for `%s` has been triggered due to having failed 3 time(s) in a row with the following description: %s\\n✕ - [CONNECTED] == true\\n✕ - [STATUS] == 200\",\"title\":\"custom-title\",\"priority\":0}", endpointName, description),
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			body := scenario.Provider.buildRequestBody(
+				&scenario.Provider.DefaultConfig,
+				&endpoint.Endpoint{Name: endpointName},
+				&scenario.Alert,
+				&endpoint.Result{
+					ConditionResults: []*endpoint.ConditionResult{
+						{Condition: "[CONNECTED] == true", Success: scenario.Resolved},
+						{Condition: "[STATUS] == 200", Success: scenario.Resolved},
+					},
+				},
+				scenario.Resolved,
+			)
+			if string(body) != scenario.ExpectedBody {
+				t.Errorf("expected:\n%s\ngot:\n%s", scenario.ExpectedBody, body)
+			}
+			out := make(map[string]interface{})
+			if err := json.Unmarshal(body, &out); err != nil {
+				t.Error("expected body to be valid JSON, got error:", err.Error())
+			}
+		})
+	}
+}
+
+func TestAlertProvider_GetDefaultAlert(t *testing.T) {
+	provider := AlertProvider{DefaultAlert: &alert.Alert{}}
+	if provider.GetDefaultAlert() != provider.DefaultAlert {
+		t.Error("expected default alert to be returned")
+	}
+}
+
+func TestAlertProvider_GetConfig(t *testing.T) {
+	scenarios := []struct {
+		Name           string
+		Provider       AlertProvider
+		InputAlert     alert.Alert
+		ExpectedOutput Config
+	}{
+		{
+			Name: "provider-no-override-should-default",
+			Provider: AlertProvider{
+				DefaultConfig: Config{ServerURL: "https://gotify.example.com", Token: "12345"},
+			},
+			InputAlert:     alert.Alert{},
+			ExpectedOutput: Config{ServerURL: "https://gotify.example.com", Token: "12345", Priority: DefaultPriority},
+		},
+		{
+			Name: "provider-with-alert-override",
+			Provider: AlertProvider{
+				DefaultConfig: Config{ServerURL: "https://gotify.example.com", Token: "12345"},
+			},
+			InputAlert:     alert.Alert{ProviderOverride: map[string]any{"server-url": "https://gotify.group-example.com", "token": "54321", "title": "alert-title", "priority": 3}},
+			ExpectedOutput: Config{ServerURL: "https://gotify.group-example.com", Token: "54321", Title: "alert-title", Priority: 3},
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			got, err := scenario.Provider.GetConfig("", &scenario.InputAlert)
+			if err != nil {
+				t.Error("expected no error, got:", err.Error())
+			}
+			if got.ServerURL != scenario.ExpectedOutput.ServerURL {
+				t.Errorf("expected server URL to be %s, got %s", scenario.ExpectedOutput.ServerURL, got.ServerURL)
+			}
+			if got.Token != scenario.ExpectedOutput.Token {
+				t.Errorf("expected token to be %s, got %s", scenario.ExpectedOutput.Token, got.Token)
+			}
+			if got.Title != scenario.ExpectedOutput.Title {
+				t.Errorf("expected title to be %s, got %s", scenario.ExpectedOutput.Title, got.Title)
+			}
+			if got.Priority != scenario.ExpectedOutput.Priority {
+				t.Errorf("expected priority to be %d, got %d", scenario.ExpectedOutput.Priority, got.Priority)
+			}
+			// Test ValidateOverrides as well, since it really just calls GetConfig
+			if err = scenario.Provider.ValidateOverrides("", &scenario.InputAlert); err != nil {
+				t.Errorf("unexpected error: %s", err)
+			}
+		})
+	}
+}

alerting/provider/incidentio/incidentio.go

@@ -0,0 +1,210 @@
+package incidentio
+
+import (
+	"bytes"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+	"strconv"
+	"strings"
+
+	"github.com/TwiN/gatus/v5/alerting/alert"
+	"github.com/TwiN/gatus/v5/client"
+	"github.com/TwiN/gatus/v5/config/endpoint"
+	"github.com/TwiN/logr"
+	"gopkg.in/yaml.v3"
+)
+
+const (
+	restAPIUrl = "https://api.incident.io/v2/alert_events/http/"
+)
+
+var (
+	ErrURLNotSet                    = errors.New("url not set")
+	ErrURLNotPrefixedWithRestAPIURL = fmt.Errorf("url must be prefixed with %s", restAPIUrl)
+	ErrDuplicateGroupOverride       = errors.New("duplicate group override")
+	ErrAuthTokenNotSet              = errors.New("auth-token not set")
+)
+
+type Config struct {
+	URL       string                 `yaml:"url,omitempty"`
+	AuthToken string                 `yaml:"auth-token,omitempty"`
+	SourceURL string                 `yaml:"source-url,omitempty"`
+	Metadata  map[string]interface{} `yaml:"metadata,omitempty"`
+}
+
+func (cfg *Config) Validate() error {
+	if len(cfg.URL) == 0 {
+		return ErrURLNotSet
+	}
+	if !strings.HasPrefix(cfg.URL, restAPIUrl) {
+		return ErrURLNotPrefixedWithRestAPIURL
+	}
+	if len(cfg.AuthToken) == 0 {
+		return ErrAuthTokenNotSet
+	}
+	return nil
+}
+
+func (cfg *Config) Merge(override *Config) {
+	if len(override.URL) > 0 {
+		cfg.URL = override.URL
+	}
+	if len(override.AuthToken) > 0 {
+		cfg.AuthToken = override.AuthToken
+	}
+	if len(override.SourceURL) > 0 {
+		cfg.SourceURL = override.SourceURL
+	}
+	if len(override.Metadata) > 0 {
+		cfg.Metadata = override.Metadata
+	}
+}
+
+// AlertProvider is the configuration necessary for sending an alert using incident.io
+type AlertProvider struct {
+	DefaultConfig Config `yaml:",inline"`
+
+	// DefaultAlert is the default alert configuration to use for endpoints with an alert of the appropriate type
+	DefaultAlert *alert.Alert `yaml:"default-alert,omitempty"`
+
+	// Overrides is a list of Override that may be prioritized over the default configuration
+	Overrides []Override `yaml:"overrides,omitempty"`
+}
+
+type Override struct {
+	Group  string `yaml:"group"`
+	Config `yaml:",inline"`
+}
+
+func (provider *AlertProvider) Validate() error {
+	registeredGroups := make(map[string]bool)
+	if provider.Overrides != nil {
+		for _, override := range provider.Overrides {
+			if isAlreadyRegistered := registeredGroups[override.Group]; isAlreadyRegistered || override.Group == "" {
+				return ErrDuplicateGroupOverride
+			}
+			registeredGroups[override.Group] = true
+		}
+	}
+	return provider.DefaultConfig.Validate()
+}
+
+func (provider *AlertProvider) Send(ep *endpoint.Endpoint, alert *alert.Alert, result *endpoint.Result, resolved bool) error {
+	cfg, err := provider.GetConfig(ep.Group, alert)
+	if err != nil {
+		return err
+	}
+	buffer := bytes.NewBuffer(provider.buildRequestBody(cfg, ep, alert, result, resolved))
+	req, err := http.NewRequest(http.MethodPost, cfg.URL, buffer)
+	if err != nil {
+		return err
+	}
+	req.Header.Set("Content-Type", "application/json")
+	req.Header.Set("Authorization", "Bearer "+cfg.AuthToken)
+	response, err := client.GetHTTPClient(nil).Do(req)
+	if err != nil {
+		return err
+	}
+	defer response.Body.Close()
+	if response.StatusCode > 399 {
+		body, _ := io.ReadAll(response.Body)
+		return fmt.Errorf("call to provider alert returned status code %d: %s", response.StatusCode, string(body))
+	}
+	incidentioResponse := Response{}
+	err = json.NewDecoder(response.Body).Decode(&incidentioResponse)
+	if err != nil {
+		// Silently fail. We don't want to create tons of alerts just because we failed to parse the body.
+		logr.Errorf("[incidentio.Send] Ran into error decoding pagerduty response: %s", err.Error())
+	}
+	alert.ResolveKey = incidentioResponse.DeduplicationKey
+	return err
+}
+
+type Body struct {
+	AlertSourceConfigID string                 `json:"alert_source_config_id"`
+	Status              string                 `json:"status"`
+	Title               string                 `json:"title"`
+	DeduplicationKey    string                 `json:"deduplication_key,omitempty"`
+	Description         string                 `json:"description,omitempty"`
+	SourceURL           string                 `json:"source_url,omitempty"`
+	Metadata            map[string]interface{} `json:"metadata,omitempty"`
+}
+
+type Response struct {
+	DeduplicationKey string `json:"deduplication_key"`
+}
+
+func (provider *AlertProvider) buildRequestBody(cfg *Config, ep *endpoint.Endpoint, alert *alert.Alert, result *endpoint.Result, resolved bool) []byte {
+	var message, formattedConditionResults, status string
+	if resolved {
+		message = "An alert has been resolved after passing successfully " + strconv.Itoa(alert.SuccessThreshold) + " time(s) in a row"
+		status = "resolved"
+	} else {
+		message = "An alert has been triggered due to having failed " + strconv.Itoa(alert.FailureThreshold) + " time(s) in a row"
+		status = "firing"
+	}
+	for _, conditionResult := range result.ConditionResults {
+		var prefix string
+		if conditionResult.Success {
+			prefix = "🟢"
+		} else {
+			prefix = "🔴"
+		}
+		// No need for \n since incident.io trims it anyways.
+		formattedConditionResults += fmt.Sprintf(" %s %s ", prefix, conditionResult.Condition)
+	}
+	if len(alert.GetDescription()) > 0 {
+		message += " with the following description: " + alert.GetDescription()
+	}
+	message += fmt.Sprintf(" and the following conditions: %s ", formattedConditionResults)
+	var body []byte
+	alertSourceID := strings.TrimPrefix(cfg.URL, restAPIUrl)
+	body, _ = json.Marshal(Body{
+		AlertSourceConfigID: alertSourceID,
+		Title:               "Gatus: " + ep.DisplayName(),
+		Status:              status,
+		DeduplicationKey:    alert.ResolveKey,
+		Description:         message,
+		SourceURL:           cfg.SourceURL,
+		Metadata:            cfg.Metadata,
+	})
+	fmt.Printf("%v", string(body))
+	return body
+
+}
+func (provider *AlertProvider) GetConfig(group string, alert *alert.Alert) (*Config, error) {
+	cfg := provider.DefaultConfig
+	// Handle group overrides
+	if provider.Overrides != nil {
+		for _, override := range provider.Overrides {
+			if group == override.Group {
+				cfg.Merge(&override.Config)
+				break
+			}
+		}
+	}
+	// Handle alert overrides
+	if len(alert.ProviderOverride) != 0 {
+		overrideConfig := Config{}
+		if err := yaml.Unmarshal(alert.ProviderOverrideAsBytes(), &overrideConfig); err != nil {
+			return nil, err
+		}
+		cfg.Merge(&overrideConfig)
+	}
+	// Validate the configuration
+	err := cfg.Validate()
+	return &cfg, err
+}
+
+// GetDefaultAlert returns the provider's default alert configuration
+func (provider *AlertProvider) GetDefaultAlert() *alert.Alert {
+	return provider.DefaultAlert
+}
+
+func (provider *AlertProvider) ValidateOverrides(group string, alert *alert.Alert) error {
+	_, err := provider.GetConfig(group, alert)
+	return err
+}

alerting/provider/incidentio/incidentio_test.go

@@ -0,0 +1,390 @@
+package incidentio
+
+import (
+	"bytes"
+	"encoding/json"
+	"io"
+	"net/http"
+	"testing"
+
+	"github.com/TwiN/gatus/v5/alerting/alert"
+	"github.com/TwiN/gatus/v5/client"
+	"github.com/TwiN/gatus/v5/config/endpoint"
+	"github.com/TwiN/gatus/v5/test"
+)
+
+func TestAlertProvider_Validate(t *testing.T) {
+	scenarios := []struct {
+		name     string
+		provider AlertProvider
+		expected bool
+	}{
+		{
+			name: "valid",
+			provider: AlertProvider{
+				DefaultConfig: Config{
+					URL:       "https://api.incident.io/v2/alert_events/http/some-id",
+					AuthToken: "some-token",
+				},
+			},
+			expected: true,
+		},
+		{
+			name: "invalid-url",
+			provider: AlertProvider{
+				DefaultConfig: Config{
+					URL:       "id-without-rest-api-url-as-prefix",
+					AuthToken: "some-token",
+				},
+			},
+			expected: false,
+		},
+		{
+			name: "invalid-missing-auth-token",
+			provider: AlertProvider{
+				DefaultConfig: Config{
+					URL: "some-id",
+				},
+			},
+			expected: false,
+		},
+		{
+			name: "invalid-missing-alert-source-config-id",
+			provider: AlertProvider{
+				DefaultConfig: Config{
+					AuthToken: "some-token",
+				},
+			},
+			expected: false,
+		},
+		{
+			name: "valid-override",
+			provider: AlertProvider{
+				DefaultConfig: Config{
+					AuthToken: "some-token",
+					URL:       "https://api.incident.io/v2/alert_events/http/some-id",
+				},
+				Overrides: []Override{{Group: "core", Config: Config{URL: "https://api.incident.io/v2/alert_events/http/another-id"}}},
+			},
+			expected: true,
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.name, func(t *testing.T) {
+			err := scenario.provider.Validate()
+			if scenario.expected && err != nil {
+				t.Error("expected no error, got", err.Error())
+			}
+			if !scenario.expected && err == nil {
+				t.Error("expected error, got none")
+			}
+		})
+	}
+}
+
+func TestAlertProvider_Send(t *testing.T) {
+	defer client.InjectHTTPClient(nil)
+	firstDescription := "description-1"
+	secondDescription := "description-2"
+	restAPIUrl := "https://api.incident.io/v2/alert_events/http/"
+	scenarios := []struct {
+		Name             string
+		Provider         AlertProvider
+		Alert            alert.Alert
+		Resolved         bool
+		MockRoundTripper test.MockRoundTripper
+		ExpectedError    bool
+	}{
+		{
+			Name: "triggered",
+			Provider: AlertProvider{DefaultConfig: Config{
+				URL:       restAPIUrl + "some-id",
+				AuthToken: "some-token",
+			}},
+			Alert:    alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: false,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				var b bytes.Buffer
+
+				response := Response{DeduplicationKey: "some-key"}
+				json.NewEncoder(&b).Encode(response)
+				reader := io.NopCloser(&b)
+				return &http.Response{StatusCode: http.StatusAccepted, Body: reader}
+			}),
+			ExpectedError: false,
+		},
+		{
+			Name: "triggered-error",
+			Provider: AlertProvider{DefaultConfig: Config{
+				URL:       restAPIUrl + "some-id",
+				AuthToken: "some-token",
+			}},
+			Alert:    alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: false,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusInternalServerError, Body: http.NoBody}
+			}),
+			ExpectedError: true,
+		},
+		{
+			Name: "resolved",
+			Provider: AlertProvider{DefaultConfig: Config{
+				URL:       restAPIUrl + "some-id",
+				AuthToken: "some-token",
+			}},
+			Alert:    alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: true,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				var b bytes.Buffer
+				response := Response{DeduplicationKey: "some-key"}
+				json.NewEncoder(&b).Encode(response)
+				reader := io.NopCloser(&b)
+				return &http.Response{StatusCode: http.StatusAccepted, Body: reader}
+			}),
+			ExpectedError: false,
+		},
+		{
+			Name:     "resolved-error",
+			Provider: AlertProvider{DefaultConfig: Config{}},
+			Alert:    alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: true,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusInternalServerError, Body: http.NoBody}
+			}),
+			ExpectedError: true,
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			client.InjectHTTPClient(&http.Client{Transport: scenario.MockRoundTripper})
+			err := scenario.Provider.Send(
+				&endpoint.Endpoint{Name: "endpoint-name"},
+				&scenario.Alert,
+				&endpoint.Result{
+					ConditionResults: []*endpoint.ConditionResult{
+						{Condition: "[CONNECTED] == true", Success: scenario.Resolved},
+						{Condition: "[STATUS] == 200", Success: scenario.Resolved},
+					},
+				},
+				scenario.Resolved,
+			)
+			if scenario.ExpectedError && err == nil {
+				t.Error("expected error, got none")
+			}
+			if !scenario.ExpectedError && err != nil {
+				t.Error("expected no error, got", err.Error())
+			}
+		})
+	}
+}
+
+func TestAlertProvider_BuildRequestBody(t *testing.T) {
+	firstDescription := "description-1"
+	secondDescription := "description-2"
+	restAPIUrl := "https://api.incident.io/v2/alert_events/http/"
+	scenarios := []struct {
+		Name         string
+		Provider     AlertProvider
+		Alert        alert.Alert
+		Resolved     bool
+		ExpectedBody string
+	}{
+		{
+			Name:         "triggered",
+			Provider:     AlertProvider{DefaultConfig: Config{URL: restAPIUrl + "some-id", AuthToken: "some-token"}},
+			Alert:        alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     false,
+			ExpectedBody: `{"alert_source_config_id":"some-id","status":"firing","title":"Gatus: endpoint-name","description":"An alert has been triggered due to having failed 3 time(s) in a row with the following description: description-1 and the following conditions:  🔴 [CONNECTED] == true  🔴 [STATUS] == 200  "}`,
+		},
+		{
+			Name:         "resolved",
+			Provider:     AlertProvider{DefaultConfig: Config{URL: restAPIUrl + "some-id", AuthToken: "some-token"}},
+			Alert:        alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     true,
+			ExpectedBody: `{"alert_source_config_id":"some-id","status":"resolved","title":"Gatus: endpoint-name","description":"An alert has been resolved after passing successfully 5 time(s) in a row with the following description: description-2 and the following conditions:  🟢 [CONNECTED] == true  🟢 [STATUS] == 200  "}`,
+		},
+		{
+			Name:         "resolved-with-metadata-source-url",
+			Provider:     AlertProvider{DefaultConfig: Config{URL: restAPIUrl + "some-id", AuthToken: "some-token", Metadata: map[string]interface{}{"service": "some-service", "team": "very-core"}, SourceURL: "some-source-url"}},
+			Alert:        alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     true,
+			ExpectedBody: `{"alert_source_config_id":"some-id","status":"resolved","title":"Gatus: endpoint-name","description":"An alert has been resolved after passing successfully 5 time(s) in a row with the following description: description-2 and the following conditions:  🟢 [CONNECTED] == true  🟢 [STATUS] == 200  ","source_url":"some-source-url","metadata":{"service":"some-service","team":"very-core"}}`,
+		},
+		{
+			Name:         "group-override",
+			Provider:     AlertProvider{DefaultConfig: Config{URL: restAPIUrl + "some-id", AuthToken: "some-token"}, Overrides: []Override{{Group: "g", Config: Config{URL: restAPIUrl + "different-id", AuthToken: "some-token"}}}},
+			Alert:        alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     false,
+			ExpectedBody: `{"alert_source_config_id":"different-id","status":"firing","title":"Gatus: endpoint-name","description":"An alert has been triggered due to having failed 3 time(s) in a row with the following description: description-1 and the following conditions:  🔴 [CONNECTED] == true  🔴 [STATUS] == 200  "}`,
+		},
+	}
+
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			cfg, err := scenario.Provider.GetConfig("g", &scenario.Alert)
+			if err != nil {
+				t.Error("expected no error, got", err.Error())
+			}
+			body := scenario.Provider.buildRequestBody(
+				cfg,
+				&endpoint.Endpoint{Name: "endpoint-name"},
+				&scenario.Alert,
+				&endpoint.Result{
+					ConditionResults: []*endpoint.ConditionResult{
+						{Condition: "[CONNECTED] == true", Success: scenario.Resolved},
+						{Condition: "[STATUS] == 200", Success: scenario.Resolved},
+					},
+				},
+				scenario.Resolved,
+			)
+			if string(body) != scenario.ExpectedBody {
+				t.Errorf("expected:\n%s\ngot:\n%s", scenario.ExpectedBody, body)
+			}
+			out := make(map[string]interface{})
+			if err := json.Unmarshal(body, &out); err != nil {
+				t.Error("expected body to be valid JSON, got error:", err.Error())
+			}
+		})
+	}
+}
+
+func TestAlertProvider_GetDefaultAlert(t *testing.T) {
+	if (&AlertProvider{DefaultAlert: &alert.Alert{}}).GetDefaultAlert() == nil {
+		t.Error("expected default alert to be not nil")
+	}
+	if (&AlertProvider{DefaultAlert: nil}).GetDefaultAlert() != nil {
+		t.Error("expected default alert to be nil")
+	}
+}
+
+func TestAlertProvider_GetConfig(t *testing.T) {
+	scenarios := []struct {
+		Name           string
+		Provider       AlertProvider
+		InputGroup     string
+		InputAlert     alert.Alert
+		ExpectedOutput Config
+	}{
+		{
+			Name: "provider-no-override-specify-no-group-should-default",
+			Provider: AlertProvider{
+				DefaultConfig: Config{URL: "https://api.incident.io/v2/alert_events/http/some-id", AuthToken: "some-token"},
+				Overrides:     nil,
+			},
+			InputGroup:     "",
+			InputAlert:     alert.Alert{},
+			ExpectedOutput: Config{URL: "https://api.incident.io/v2/alert_events/http/some-id", AuthToken: "some-token"},
+		},
+		{
+			Name: "provider-no-override-specify-group-should-default",
+			Provider: AlertProvider{
+				DefaultConfig: Config{URL: "https://api.incident.io/v2/alert_events/http/some-id", AuthToken: "some-token"},
+				Overrides:     nil,
+			},
+			InputGroup:     "group",
+			InputAlert:     alert.Alert{},
+			ExpectedOutput: Config{URL: "https://api.incident.io/v2/alert_events/http/some-id", AuthToken: "some-token"},
+		},
+		{
+			Name: "provider-with-override-specify-no-group-should-default",
+			Provider: AlertProvider{
+				DefaultConfig: Config{URL: "https://api.incident.io/v2/alert_events/http/some-id", AuthToken: "some-token"},
+				Overrides: []Override{
+					{
+						Group:  "group",
+						Config: Config{URL: "https://api.incident.io/v2/alert_events/http/diff-id"},
+					},
+				},
+			},
+			InputGroup:     "",
+			InputAlert:     alert.Alert{},
+			ExpectedOutput: Config{URL: "https://api.incident.io/v2/alert_events/http/some-id", AuthToken: "some-token"},
+		},
+		{
+			Name: "provider-with-override-specify-group-should-override",
+			Provider: AlertProvider{
+				DefaultConfig: Config{URL: "https://api.incident.io/v2/alert_events/http/some-id", AuthToken: "some-token"},
+				Overrides: []Override{
+					{
+						Group:  "group",
+						Config: Config{URL: "https://api.incident.io/v2/alert_events/http/diff-id", AuthToken: "some-token"},
+					},
+				},
+			},
+			InputGroup:     "group",
+			InputAlert:     alert.Alert{},
+			ExpectedOutput: Config{URL: "https://api.incident.io/v2/alert_events/http/diff-id", AuthToken: "some-token"},
+		},
+		{
+			Name: "provider-with-group-override-and-alert-override--alert-override-should-take-precedence",
+			Provider: AlertProvider{
+				DefaultConfig: Config{URL: "https://api.incident.io/v2/alert_events/http/some-id", AuthToken: "some-token"},
+				Overrides: []Override{
+					{
+						Group:  "group",
+						Config: Config{URL: "https://api.incident.io/v2/alert_events/http/diff-id", AuthToken: "some-token"},
+					},
+				},
+			},
+			InputGroup:     "group",
+			InputAlert:     alert.Alert{ProviderOverride: map[string]any{"url": "https://api.incident.io/v2/alert_events/http/another-id"}},
+			ExpectedOutput: Config{URL: "https://api.incident.io/v2/alert_events/http/another-id", AuthToken: "some-token"},
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			got, err := scenario.Provider.GetConfig(scenario.InputGroup, &scenario.InputAlert)
+			if err != nil {
+				t.Fatalf("unexpected error: %s", err)
+			}
+			if got.URL != scenario.ExpectedOutput.URL {
+				t.Errorf("expected alert source config to be %s, got %s", scenario.ExpectedOutput.URL, got.URL)
+			}
+			if got.AuthToken != scenario.ExpectedOutput.AuthToken {
+				t.Errorf("expected alert auth token to be %s, got %s", scenario.ExpectedOutput.AuthToken, got.AuthToken)
+			}
+
+			// Test ValidateOverrides as well, since it really just calls GetConfig
+			if err = scenario.Provider.ValidateOverrides(scenario.InputGroup, &scenario.InputAlert); err != nil {
+				t.Errorf("unexpected error: %s", err)
+			}
+		})
+	}
+}
+
+func TestAlertProvider_ValidateWithOverride(t *testing.T) {
+	providerWithInvalidOverrideGroup := AlertProvider{
+		Overrides: []Override{
+			{
+				Config: Config{URL: "https://api.incident.io/v2/alert_events/http/some-id", AuthToken: "some-token"},
+				Group:  "",
+			},
+		},
+	}
+	if err := providerWithInvalidOverrideGroup.Validate(); err == nil {
+		t.Error("provider Group shouldn't have been valid")
+	}
+	providerWithInvalidOverrideTo := AlertProvider{
+		Overrides: []Override{
+			{
+				Config: Config{URL: "", AuthToken: "some-token"},
+				Group:  "group",
+			},
+		},
+	}
+	if err := providerWithInvalidOverrideTo.Validate(); err == nil {
+		t.Error("provider integration key shouldn't have been valid")
+	}
+	providerWithValidOverride := AlertProvider{
+		DefaultConfig: Config{URL: "https://api.incident.io/v2/alert_events/http/nice-id", AuthToken: "some-token"},
+		Overrides: []Override{
+			{
+				Config: Config{URL: "https://api.incident.io/v2/alert_events/http/very-good-id", AuthToken: "some-token"},
+				Group:  "group",
+			},
+		},
+	}
+	if err := providerWithValidOverride.Validate(); err != nil {
+		t.Error("provider should've been valid")
+	}
+}

alerting/provider/jetbrainsspace/jetbrainsspace.go

@@ -0,0 +1,223 @@
+package jetbrainsspace
+
+import (
+	"bytes"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+
+	"github.com/TwiN/gatus/v5/alerting/alert"
+	"github.com/TwiN/gatus/v5/client"
+	"github.com/TwiN/gatus/v5/config/endpoint"
+	"gopkg.in/yaml.v3"
+)
+
+var (
+	ErrProjectNotSet          = errors.New("project not set")
+	ErrChannelIDNotSet        = errors.New("channel-id not set")
+	ErrTokenNotSet            = errors.New("token not set")
+	ErrDuplicateGroupOverride = errors.New("duplicate group override")
+)
+
+type Config struct {
+	Project   string `yaml:"project"`    // Project name
+	ChannelID string `yaml:"channel-id"` // Chat Channel ID
+	Token     string `yaml:"token"`      // Bearer Token
+}
+
+func (cfg *Config) Validate() error {
+	if len(cfg.Project) == 0 {
+		return ErrProjectNotSet
+	}
+	if len(cfg.ChannelID) == 0 {
+		return ErrChannelIDNotSet
+	}
+	if len(cfg.Token) == 0 {
+		return ErrTokenNotSet
+	}
+	return nil
+}
+
+func (cfg *Config) Merge(override *Config) {
+	if len(override.Project) > 0 {
+		cfg.Project = override.Project
+	}
+	if len(override.ChannelID) > 0 {
+		cfg.ChannelID = override.ChannelID
+	}
+	if len(override.Token) > 0 {
+		cfg.Token = override.Token
+	}
+}
+
+// AlertProvider is the configuration necessary for sending an alert using JetBrains Space
+type AlertProvider struct {
+	DefaultConfig Config `yaml:",inline"`
+
+	// DefaultAlert is the default alert configuration to use for endpoints with an alert of the appropriate type
+	DefaultAlert *alert.Alert `yaml:"default-alert,omitempty"`
+
+	// Overrides is a list of Override that may be prioritized over the default configuration
+	Overrides []Override `yaml:"overrides,omitempty"`
+}
+
+// Override is a case under which the default integration is overridden
+type Override struct {
+	Group  string `yaml:"group"`
+	Config `yaml:",inline"`
+}
+
+// Validate the provider's configuration
+func (provider *AlertProvider) Validate() error {
+	registeredGroups := make(map[string]bool)
+	if provider.Overrides != nil {
+		for _, override := range provider.Overrides {
+			if isAlreadyRegistered := registeredGroups[override.Group]; isAlreadyRegistered || override.Group == "" {
+				return ErrDuplicateGroupOverride
+			}
+			registeredGroups[override.Group] = true
+		}
+	}
+	return provider.DefaultConfig.Validate()
+}
+
+// Send an alert using the provider
+func (provider *AlertProvider) Send(ep *endpoint.Endpoint, alert *alert.Alert, result *endpoint.Result, resolved bool) error {
+	cfg, err := provider.GetConfig(ep.Group, alert)
+	if err != nil {
+		return err
+	}
+	buffer := bytes.NewBuffer(provider.buildRequestBody(cfg, ep, alert, result, resolved))
+	url := fmt.Sprintf("https://%s.jetbrains.space/api/http/chats/messages/send-message", cfg.Project)
+	request, err := http.NewRequest(http.MethodPost, url, buffer)
+	if err != nil {
+		return err
+	}
+	request.Header.Set("Content-Type", "application/json")
+	request.Header.Set("Authorization", "Bearer "+cfg.Token)
+	response, err := client.GetHTTPClient(nil).Do(request)
+	if err != nil {
+		return err
+	}
+	defer response.Body.Close()
+	if response.StatusCode > 399 {
+		body, _ := io.ReadAll(response.Body)
+		return fmt.Errorf("call to provider alert returned status code %d: %s", response.StatusCode, string(body))
+	}
+	return err
+}
+
+type Body struct {
+	Channel string  `json:"channel"`
+	Content Content `json:"content"`
+}
+
+type Content struct {
+	ClassName string    `json:"className"`
+	Style     string    `json:"style"`
+	Sections  []Section `json:"sections,omitempty"`
+}
+
+type Section struct {
+	ClassName string    `json:"className"`
+	Elements  []Element `json:"elements"`
+	Header    string    `json:"header"`
+}
+
+type Element struct {
+	ClassName string    `json:"className"`
+	Accessory Accessory `json:"accessory"`
+	Style     string    `json:"style"`
+	Size      string    `json:"size"`
+	Content   string    `json:"content"`
+}
+
+type Accessory struct {
+	ClassName string `json:"className"`
+	Icon      Icon   `json:"icon"`
+	Style     string `json:"style"`
+}
+
+type Icon struct {
+	Icon string `json:"icon"`
+}
+
+// buildRequestBody builds the request body for the provider
+func (provider *AlertProvider) buildRequestBody(cfg *Config, ep *endpoint.Endpoint, alert *alert.Alert, result *endpoint.Result, resolved bool) []byte {
+	body := Body{
+		Channel: "id:" + cfg.ChannelID,
+		Content: Content{
+			ClassName: "ChatMessage.Block",
+			Sections: []Section{{
+				ClassName: "MessageSection",
+				Elements:  []Element{},
+			}},
+		},
+	}
+	if resolved {
+		body.Content.Style = "SUCCESS"
+		body.Content.Sections[0].Header = fmt.Sprintf("An alert for *%s* has been resolved after passing successfully %d time(s) in a row", ep.DisplayName(), alert.SuccessThreshold)
+	} else {
+		body.Content.Style = "WARNING"
+		body.Content.Sections[0].Header = fmt.Sprintf("An alert for *%s* has been triggered due to having failed %d time(s) in a row", ep.DisplayName(), alert.FailureThreshold)
+	}
+	for _, conditionResult := range result.ConditionResults {
+		icon := "warning"
+		style := "WARNING"
+		if conditionResult.Success {
+			icon = "success"
+			style = "SUCCESS"
+		}
+		body.Content.Sections[0].Elements = append(body.Content.Sections[0].Elements, Element{
+			ClassName: "MessageText",
+			Accessory: Accessory{
+				ClassName: "MessageIcon",
+				Icon:      Icon{Icon: icon},
+				Style:     style,
+			},
+			Style:   style,
+			Size:    "REGULAR",
+			Content: conditionResult.Condition,
+		})
+	}
+	bodyAsJSON, _ := json.Marshal(body)
+	return bodyAsJSON
+}
+
+// GetDefaultAlert returns the provider's default alert configuration
+func (provider *AlertProvider) GetDefaultAlert() *alert.Alert {
+	return provider.DefaultAlert
+}
+
+// GetConfig returns the configuration for the provider with the overrides applied
+func (provider *AlertProvider) GetConfig(group string, alert *alert.Alert) (*Config, error) {
+	cfg := provider.DefaultConfig
+	// Handle group overrides
+	if provider.Overrides != nil {
+		for _, override := range provider.Overrides {
+			if group == override.Group {
+				cfg.Merge(&override.Config)
+				break
+			}
+		}
+	}
+	// Handle alert overrides
+	if len(alert.ProviderOverride) != 0 {
+		overrideConfig := Config{}
+		if err := yaml.Unmarshal(alert.ProviderOverrideAsBytes(), &overrideConfig); err != nil {
+			return nil, err
+		}
+		cfg.Merge(&overrideConfig)
+	}
+	// Validate the configuration
+	err := cfg.Validate()
+	return &cfg, err
+}
+
+// ValidateOverrides validates the alert's provider override and, if present, the group override
+func (provider *AlertProvider) ValidateOverrides(group string, alert *alert.Alert) error {
+	_, err := provider.GetConfig(group, alert)
+	return err
+}

alerting/provider/jetbrainsspace/jetbrainsspace_test.go

@@ -0,0 +1,318 @@
+package jetbrainsspace
+
+import (
+	"encoding/json"
+	"net/http"
+	"testing"
+
+	"github.com/TwiN/gatus/v5/alerting/alert"
+	"github.com/TwiN/gatus/v5/client"
+	"github.com/TwiN/gatus/v5/config/endpoint"
+	"github.com/TwiN/gatus/v5/test"
+)
+
+func TestAlertProvider_Validate(t *testing.T) {
+	invalidProvider := AlertProvider{DefaultConfig: Config{Project: ""}}
+	if err := invalidProvider.Validate(); err == nil {
+		t.Error("provider shouldn't have been valid")
+	}
+	validProvider := AlertProvider{DefaultConfig: Config{Project: "foo", ChannelID: "bar", Token: "baz"}}
+	if err := validProvider.Validate(); err != nil {
+		t.Error("provider should've been valid")
+	}
+}
+
+func TestAlertProvider_ValidateWithOverride(t *testing.T) {
+	providerWithInvalidOverrideGroup := AlertProvider{
+		DefaultConfig: Config{Project: "foobar"},
+		Overrides: []Override{
+			{
+				Config: Config{ChannelID: "http://example.com"},
+				Group:  "",
+			},
+		},
+	}
+	if err := providerWithInvalidOverrideGroup.Validate(); err == nil {
+		t.Error("provider Group shouldn't have been valid")
+	}
+	providerWithInvalidOverrideTo := AlertProvider{
+		DefaultConfig: Config{Project: "foobar"},
+		Overrides: []Override{
+			{
+				Config: Config{ChannelID: ""},
+				Group:  "group",
+			},
+		},
+	}
+	if err := providerWithInvalidOverrideTo.Validate(); err == nil {
+		t.Error("provider integration key shouldn't have been valid")
+	}
+	providerWithValidOverride := AlertProvider{
+		DefaultConfig: Config{
+			Project:   "foo",
+			ChannelID: "bar",
+			Token:     "baz",
+		},
+		Overrides: []Override{
+			{
+				Config: Config{ChannelID: "foobar"},
+				Group:  "group",
+			},
+		},
+	}
+	if err := providerWithValidOverride.Validate(); err != nil {
+		t.Error("provider should've been valid")
+	}
+}
+
+func TestAlertProvider_Send(t *testing.T) {
+	defer client.InjectHTTPClient(nil)
+	firstDescription := "description-1"
+	secondDescription := "description-2"
+	scenarios := []struct {
+		Name             string
+		Provider         AlertProvider
+		Alert            alert.Alert
+		Resolved         bool
+		MockRoundTripper test.MockRoundTripper
+		ExpectedError    bool
+	}{
+		{
+			Name:     "triggered",
+			Provider: AlertProvider{DefaultConfig: Config{ChannelID: "1", Project: "project", Token: "token"}},
+			Alert:    alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: false,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusOK, Body: http.NoBody}
+			}),
+			ExpectedError: false,
+		},
+		{
+			Name:     "triggered-error",
+			Provider: AlertProvider{DefaultConfig: Config{ChannelID: "1", Project: "project", Token: "token"}},
+			Alert:    alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: false,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusInternalServerError, Body: http.NoBody}
+			}),
+			ExpectedError: true,
+		},
+		{
+			Name:     "resolved",
+			Provider: AlertProvider{DefaultConfig: Config{ChannelID: "1", Project: "project", Token: "token"}},
+			Alert:    alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: true,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusOK, Body: http.NoBody}
+			}),
+			ExpectedError: false,
+		},
+		{
+			Name:     "resolved-error",
+			Provider: AlertProvider{DefaultConfig: Config{ChannelID: "1", Project: "project", Token: "token"}},
+			Alert:    alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: true,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusInternalServerError, Body: http.NoBody}
+			}),
+			ExpectedError: true,
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			client.InjectHTTPClient(&http.Client{Transport: scenario.MockRoundTripper})
+			err := scenario.Provider.Send(
+				&endpoint.Endpoint{Name: "endpoint-name"},
+				&scenario.Alert,
+				&endpoint.Result{
+					ConditionResults: []*endpoint.ConditionResult{
+						{Condition: "[CONNECTED] == true", Success: scenario.Resolved},
+						{Condition: "[STATUS] == 200", Success: scenario.Resolved},
+					},
+				},
+				scenario.Resolved,
+			)
+			if scenario.ExpectedError && err == nil {
+				t.Error("expected error, got none")
+			}
+			if !scenario.ExpectedError && err != nil {
+				t.Error("expected no error, got", err.Error())
+			}
+		})
+	}
+}
+
+func TestAlertProvider_buildRequestBody(t *testing.T) {
+	firstDescription := "description-1"
+	secondDescription := "description-2"
+	scenarios := []struct {
+		Name         string
+		Provider     AlertProvider
+		Endpoint     endpoint.Endpoint
+		Alert        alert.Alert
+		Resolved     bool
+		ExpectedBody string
+	}{
+		{
+			Name:         "triggered",
+			Provider:     AlertProvider{DefaultConfig: Config{ChannelID: "1", Project: "project"}},
+			Endpoint:     endpoint.Endpoint{Name: "name"},
+			Alert:        alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     false,
+			ExpectedBody: `{"channel":"id:1","content":{"className":"ChatMessage.Block","style":"WARNING","sections":[{"className":"MessageSection","elements":[{"className":"MessageText","accessory":{"className":"MessageIcon","icon":{"icon":"warning"},"style":"WARNING"},"style":"WARNING","size":"REGULAR","content":"[CONNECTED] == true"},{"className":"MessageText","accessory":{"className":"MessageIcon","icon":{"icon":"warning"},"style":"WARNING"},"style":"WARNING","size":"REGULAR","content":"[STATUS] == 200"}],"header":"An alert for *name* has been triggered due to having failed 3 time(s) in a row"}]}}`,
+		},
+		{
+			Name:         "triggered-with-group",
+			Provider:     AlertProvider{DefaultConfig: Config{ChannelID: "1", Project: "project"}},
+			Endpoint:     endpoint.Endpoint{Name: "name", Group: "group"},
+			Alert:        alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     false,
+			ExpectedBody: `{"channel":"id:1","content":{"className":"ChatMessage.Block","style":"WARNING","sections":[{"className":"MessageSection","elements":[{"className":"MessageText","accessory":{"className":"MessageIcon","icon":{"icon":"warning"},"style":"WARNING"},"style":"WARNING","size":"REGULAR","content":"[CONNECTED] == true"},{"className":"MessageText","accessory":{"className":"MessageIcon","icon":{"icon":"warning"},"style":"WARNING"},"style":"WARNING","size":"REGULAR","content":"[STATUS] == 200"}],"header":"An alert for *group/name* has been triggered due to having failed 3 time(s) in a row"}]}}`,
+		},
+		{
+			Name:         "resolved",
+			Provider:     AlertProvider{DefaultConfig: Config{ChannelID: "1", Project: "project"}},
+			Endpoint:     endpoint.Endpoint{Name: "name"},
+			Alert:        alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     true,
+			ExpectedBody: `{"channel":"id:1","content":{"className":"ChatMessage.Block","style":"SUCCESS","sections":[{"className":"MessageSection","elements":[{"className":"MessageText","accessory":{"className":"MessageIcon","icon":{"icon":"success"},"style":"SUCCESS"},"style":"SUCCESS","size":"REGULAR","content":"[CONNECTED] == true"},{"className":"MessageText","accessory":{"className":"MessageIcon","icon":{"icon":"success"},"style":"SUCCESS"},"style":"SUCCESS","size":"REGULAR","content":"[STATUS] == 200"}],"header":"An alert for *name* has been resolved after passing successfully 5 time(s) in a row"}]}}`,
+		},
+		{
+			Name:         "resolved-with-group",
+			Provider:     AlertProvider{DefaultConfig: Config{ChannelID: "1", Project: "project"}},
+			Endpoint:     endpoint.Endpoint{Name: "name", Group: "group"},
+			Alert:        alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     true,
+			ExpectedBody: `{"channel":"id:1","content":{"className":"ChatMessage.Block","style":"SUCCESS","sections":[{"className":"MessageSection","elements":[{"className":"MessageText","accessory":{"className":"MessageIcon","icon":{"icon":"success"},"style":"SUCCESS"},"style":"SUCCESS","size":"REGULAR","content":"[CONNECTED] == true"},{"className":"MessageText","accessory":{"className":"MessageIcon","icon":{"icon":"success"},"style":"SUCCESS"},"style":"SUCCESS","size":"REGULAR","content":"[STATUS] == 200"}],"header":"An alert for *group/name* has been resolved after passing successfully 5 time(s) in a row"}]}}`,
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			body := scenario.Provider.buildRequestBody(
+				&scenario.Provider.DefaultConfig,
+				&scenario.Endpoint,
+				&scenario.Alert,
+				&endpoint.Result{
+					ConditionResults: []*endpoint.ConditionResult{
+						{Condition: "[CONNECTED] == true", Success: scenario.Resolved},
+						{Condition: "[STATUS] == 200", Success: scenario.Resolved},
+					},
+				},
+				scenario.Resolved,
+			)
+			if string(body) != scenario.ExpectedBody {
+				t.Errorf("expected:\n%s\ngot:\n%s", scenario.ExpectedBody, body)
+			}
+			out := make(map[string]interface{})
+			if err := json.Unmarshal(body, &out); err != nil {
+				t.Error("expected body to be valid JSON, got error:", err.Error())
+			}
+		})
+	}
+}
+
+func TestAlertProvider_GetDefaultAlert(t *testing.T) {
+	if (&AlertProvider{DefaultAlert: &alert.Alert{}}).GetDefaultAlert() == nil {
+		t.Error("expected default alert to be not nil")
+	}
+	if (&AlertProvider{DefaultAlert: nil}).GetDefaultAlert() != nil {
+		t.Error("expected default alert to be nil")
+	}
+}
+
+func TestAlertProvider_GetConfig(t *testing.T) {
+	scenarios := []struct {
+		Name           string
+		Provider       AlertProvider
+		InputGroup     string
+		InputAlert     alert.Alert
+		ExpectedOutput Config
+	}{
+		{
+			Name: "provider-no-override-specify-no-group-should-default",
+			Provider: AlertProvider{
+				DefaultConfig: Config{ChannelID: "default", Project: "project", Token: "token"},
+				Overrides:     nil,
+			},
+			InputGroup:     "",
+			InputAlert:     alert.Alert{},
+			ExpectedOutput: Config{ChannelID: "default", Project: "project", Token: "token"},
+		},
+		{
+			Name: "provider-no-override-specify-group-should-default",
+			Provider: AlertProvider{
+				DefaultConfig: Config{ChannelID: "default", Project: "project", Token: "token"},
+				Overrides:     nil,
+			},
+			InputGroup:     "group",
+			InputAlert:     alert.Alert{},
+			ExpectedOutput: Config{ChannelID: "default", Project: "project", Token: "token"},
+		},
+		{
+			Name: "provider-with-override-specify-no-group-should-default",
+			Provider: AlertProvider{
+				DefaultConfig: Config{ChannelID: "default", Project: "project", Token: "token"},
+				Overrides: []Override{
+					{
+						Group:  "group",
+						Config: Config{ChannelID: "group-channel"},
+					},
+				},
+			},
+			InputGroup:     "",
+			InputAlert:     alert.Alert{},
+			ExpectedOutput: Config{ChannelID: "default", Project: "project", Token: "token"},
+		},
+		{
+			Name: "provider-with-override-specify-group-should-override",
+			Provider: AlertProvider{
+				DefaultConfig: Config{ChannelID: "default", Project: "project", Token: "token"},
+				Overrides: []Override{
+					{
+						Group:  "group",
+						Config: Config{ChannelID: "group-channel"},
+					},
+				},
+			},
+			InputGroup:     "group",
+			InputAlert:     alert.Alert{},
+			ExpectedOutput: Config{ChannelID: "group-channel", Project: "project", Token: "token"},
+		},
+		{
+			Name: "provider-with-group-override-and-alert-override--alert-override-should-take-precedence",
+			Provider: AlertProvider{
+				DefaultConfig: Config{ChannelID: "default", Project: "project", Token: "token"},
+				Overrides: []Override{
+					{
+						Group:  "group",
+						Config: Config{ChannelID: "group-channel"},
+					},
+				},
+			},
+			InputGroup:     "group",
+			InputAlert:     alert.Alert{ProviderOverride: map[string]any{"channel-id": "alert-channel", "project": "alert-project", "token": "alert-token"}},
+			ExpectedOutput: Config{ChannelID: "alert-channel", Project: "alert-project", Token: "alert-token"},
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			got, err := scenario.Provider.GetConfig(scenario.InputGroup, &scenario.InputAlert)
+			if err != nil {
+				t.Fatalf("unexpected error: %s", err)
+			}
+			if got.ChannelID != scenario.ExpectedOutput.ChannelID {
+				t.Errorf("expected %s, got %s", scenario.ExpectedOutput.ChannelID, got.ChannelID)
+			}
+			if got.Project != scenario.ExpectedOutput.Project {
+				t.Errorf("expected %s, got %s", scenario.ExpectedOutput.Project, got.Project)
+			}
+			if got.Token != scenario.ExpectedOutput.Token {
+				t.Errorf("expected %s, got %s", scenario.ExpectedOutput.Token, got.Token)
+			}
+			// Test ValidateOverrides as well, since it really just calls GetConfig
+			if err = scenario.Provider.ValidateOverrides(scenario.InputGroup, &scenario.InputAlert); err != nil {
+				t.Errorf("unexpected error: %s", err)
+			}
+		})
+	}
+}

alerting/provider/matrix/matrix.go

@@ -0,0 +1,247 @@
+package matrix
+
+import (
+	"bytes"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"math/rand"
+	"net/http"
+	"net/url"
+	"time"
+
+	"github.com/TwiN/gatus/v5/alerting/alert"
+	"github.com/TwiN/gatus/v5/client"
+	"github.com/TwiN/gatus/v5/config/endpoint"
+	"gopkg.in/yaml.v3"
+)
+
+const defaultServerURL = "https://matrix-client.matrix.org"
+
+var (
+	ErrAccessTokenNotSet      = errors.New("access-token not set")
+	ErrInternalRoomID         = errors.New("internal-room-id not set")
+	ErrDuplicateGroupOverride = errors.New("duplicate group override")
+)
+
+type Config struct {
+	// ServerURL is the custom homeserver to use (optional)
+	ServerURL string `yaml:"server-url"`
+
+	// AccessToken is the bot user's access token to send messages
+	AccessToken string `yaml:"access-token"`
+
+	// InternalRoomID is the room that the bot user has permissions to send messages to
+	InternalRoomID string `yaml:"internal-room-id"`
+}
+
+func (cfg *Config) Validate() error {
+	if len(cfg.ServerURL) == 0 {
+		cfg.ServerURL = defaultServerURL
+	}
+	if len(cfg.AccessToken) == 0 {
+		return ErrAccessTokenNotSet
+	}
+	if len(cfg.InternalRoomID) == 0 {
+		return ErrInternalRoomID
+	}
+	return nil
+}
+
+func (cfg *Config) Merge(override *Config) {
+	if len(override.ServerURL) > 0 {
+		cfg.ServerURL = override.ServerURL
+	}
+	if len(override.AccessToken) > 0 {
+		cfg.AccessToken = override.AccessToken
+	}
+	if len(override.InternalRoomID) > 0 {
+		cfg.InternalRoomID = override.InternalRoomID
+	}
+}
+
+// AlertProvider is the configuration necessary for sending an alert using Matrix
+type AlertProvider struct {
+	DefaultConfig Config `yaml:",inline"`
+
+	// DefaultAlert is the default alert configuration to use for endpoints with an alert of the appropriate type
+	DefaultAlert *alert.Alert `yaml:"default-alert,omitempty"`
+
+	// Overrides is a list of Override that may be prioritized over the default configuration
+	Overrides []Override `yaml:"overrides,omitempty"`
+}
+
+// Override is a case under which the default integration is overridden
+type Override struct {
+	Group  string `yaml:"group"`
+	Config `yaml:",inline"`
+}
+
+// Validate the provider's configuration
+func (provider *AlertProvider) Validate() error {
+	registeredGroups := make(map[string]bool)
+	if provider.Overrides != nil {
+		for _, override := range provider.Overrides {
+			if isAlreadyRegistered := registeredGroups[override.Group]; isAlreadyRegistered || override.Group == "" || len(override.AccessToken) == 0 || len(override.InternalRoomID) == 0 {
+				return ErrDuplicateGroupOverride
+			}
+			registeredGroups[override.Group] = true
+		}
+	}
+	return provider.DefaultConfig.Validate()
+}
+
+// Send an alert using the provider
+func (provider *AlertProvider) Send(ep *endpoint.Endpoint, alert *alert.Alert, result *endpoint.Result, resolved bool) error {
+	cfg, err := provider.GetConfig(ep.Group, alert)
+	if err != nil {
+		return err
+	}
+	buffer := bytes.NewBuffer(provider.buildRequestBody(ep, alert, result, resolved))
+	// The Matrix endpoint requires a unique transaction ID for each event sent
+	txnId := randStringBytes(24)
+	request, err := http.NewRequest(
+		http.MethodPut,
+		fmt.Sprintf("%s/_matrix/client/v3/rooms/%s/send/m.room.message/%s?access_token=%s",
+			cfg.ServerURL,
+			url.PathEscape(cfg.InternalRoomID),
+			txnId,
+			url.QueryEscape(cfg.AccessToken),
+		),
+		buffer,
+	)
+	if err != nil {
+		return err
+	}
+	request.Header.Set("Content-Type", "application/json")
+	response, err := client.GetHTTPClient(nil).Do(request)
+	if err != nil {
+		return err
+	}
+	defer response.Body.Close()
+	if response.StatusCode > 399 {
+		body, _ := io.ReadAll(response.Body)
+		return fmt.Errorf("call to provider alert returned status code %d: %s", response.StatusCode, string(body))
+	}
+	return err
+}
+
+type Body struct {
+	MsgType       string `json:"msgtype"`
+	Format        string `json:"format"`
+	Body          string `json:"body"`
+	FormattedBody string `json:"formatted_body"`
+}
+
+// buildRequestBody builds the request body for the provider
+func (provider *AlertProvider) buildRequestBody(ep *endpoint.Endpoint, alert *alert.Alert, result *endpoint.Result, resolved bool) []byte {
+	body, _ := json.Marshal(Body{
+		MsgType:       "m.text",
+		Format:        "org.matrix.custom.html",
+		Body:          buildPlaintextMessageBody(ep, alert, result, resolved),
+		FormattedBody: buildHTMLMessageBody(ep, alert, result, resolved),
+	})
+	return body
+}
+
+// buildPlaintextMessageBody builds the message body in plaintext to include in request
+func buildPlaintextMessageBody(ep *endpoint.Endpoint, alert *alert.Alert, result *endpoint.Result, resolved bool) string {
+	var message string
+	if resolved {
+		message = fmt.Sprintf("An alert for `%s` has been resolved after passing successfully %d time(s) in a row", ep.DisplayName(), alert.SuccessThreshold)
+	} else {
+		message = fmt.Sprintf("An alert for `%s` has been triggered due to having failed %d time(s) in a row", ep.DisplayName(), alert.FailureThreshold)
+	}
+	var formattedConditionResults string
+	for _, conditionResult := range result.ConditionResults {
+		var prefix string
+		if conditionResult.Success {
+			prefix = "✓"
+		} else {
+			prefix = "✕"
+		}
+		formattedConditionResults += fmt.Sprintf("\n%s - %s", prefix, conditionResult.Condition)
+	}
+	var description string
+	if alertDescription := alert.GetDescription(); len(alertDescription) > 0 {
+		description = "\n" + alertDescription
+	}
+	return fmt.Sprintf("%s%s\n%s", message, description, formattedConditionResults)
+}
+
+// buildHTMLMessageBody builds the message body in HTML to include in request
+func buildHTMLMessageBody(ep *endpoint.Endpoint, alert *alert.Alert, result *endpoint.Result, resolved bool) string {
+	var message string
+	if resolved {
+		message = fmt.Sprintf("An alert for <code>%s</code> has been resolved after passing successfully %d time(s) in a row", ep.DisplayName(), alert.SuccessThreshold)
+	} else {
+		message = fmt.Sprintf("An alert for <code>%s</code> has been triggered due to having failed %d time(s) in a row", ep.DisplayName(), alert.FailureThreshold)
+	}
+	var formattedConditionResults string
+	if len(result.ConditionResults) > 0 {
+		formattedConditionResults = "\n<h5>Condition results</h5><ul>"
+		for _, conditionResult := range result.ConditionResults {
+			var prefix string
+			if conditionResult.Success {
+				prefix = "✅"
+			} else {
+				prefix = "❌"
+			}
+			formattedConditionResults += fmt.Sprintf("<li>%s - <code>%s</code></li>", prefix, conditionResult.Condition)
+		}
+		formattedConditionResults += "</ul>"
+	}
+	var description string
+	if alertDescription := alert.GetDescription(); len(alertDescription) > 0 {
+		description = fmt.Sprintf("\n<blockquote>%s</blockquote>", alertDescription)
+	}
+	return fmt.Sprintf("<h3>%s</h3>%s%s", message, description, formattedConditionResults)
+}
+
+func randStringBytes(n int) string {
+	// All the compatible characters to use in a transaction ID
+	const availableCharacterBytes = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
+	b := make([]byte, n)
+	rand.Seed(time.Now().UnixNano())
+	for i := range b {
+		b[i] = availableCharacterBytes[rand.Intn(len(availableCharacterBytes))]
+	}
+	return string(b)
+}
+
+// GetDefaultAlert returns the provider's default alert configuration
+func (provider *AlertProvider) GetDefaultAlert() *alert.Alert {
+	return provider.DefaultAlert
+}
+
+// GetConfig returns the configuration for the provider with the overrides applied
+func (provider *AlertProvider) GetConfig(group string, alert *alert.Alert) (*Config, error) {
+	cfg := provider.DefaultConfig
+	// Handle group overrides
+	if provider.Overrides != nil {
+		for _, override := range provider.Overrides {
+			if group == override.Group {
+				cfg.Merge(&override.Config)
+				break
+			}
+		}
+	}
+	// Handle alert overrides
+	if len(alert.ProviderOverride) != 0 {
+		overrideConfig := Config{}
+		if err := yaml.Unmarshal(alert.ProviderOverrideAsBytes(), &overrideConfig); err != nil {
+			return nil, err
+		}
+		cfg.Merge(&overrideConfig)
+	}
+	// Validate the configuration
+	err := cfg.Validate()
+	return &cfg, err
+}
+
+// ValidateOverrides validates the alert's provider override and, if present, the group override
+func (provider *AlertProvider) ValidateOverrides(group string, alert *alert.Alert) error {
+	_, err := provider.GetConfig(group, alert)
+	return err
+}

alerting/provider/matrix/matrix_test.go

@@ -0,0 +1,387 @@
+package matrix
+
+import (
+	"encoding/json"
+	"net/http"
+	"testing"
+
+	"github.com/TwiN/gatus/v5/alerting/alert"
+	"github.com/TwiN/gatus/v5/client"
+	"github.com/TwiN/gatus/v5/config/endpoint"
+	"github.com/TwiN/gatus/v5/test"
+)
+
+func TestAlertProvider_Validate(t *testing.T) {
+	invalidProvider := AlertProvider{
+		DefaultConfig: Config{
+			AccessToken:    "",
+			InternalRoomID: "",
+		},
+	}
+	if err := invalidProvider.Validate(); err == nil {
+		t.Error("provider shouldn't have been valid")
+	}
+	validProvider := AlertProvider{
+		DefaultConfig: Config{
+			AccessToken:    "1",
+			InternalRoomID: "!a:example.com",
+		},
+	}
+	if err := validProvider.Validate(); err != nil {
+		t.Error("provider should've been valid")
+	}
+	validProviderWithHomeserver := AlertProvider{
+		DefaultConfig: Config{
+			ServerURL:      "https://example.com",
+			AccessToken:    "1",
+			InternalRoomID: "!a:example.com",
+		},
+	}
+	if err := validProviderWithHomeserver.Validate(); err != nil {
+		t.Error("provider with homeserver should've been valid")
+	}
+}
+
+func TestAlertProvider_ValidateWithOverride(t *testing.T) {
+	providerWithInvalidOverrideGroup := AlertProvider{
+		Overrides: []Override{
+			{
+				Group: "",
+				Config: Config{
+					AccessToken:    "",
+					InternalRoomID: "",
+				},
+			},
+		},
+	}
+	if err := providerWithInvalidOverrideGroup.Validate(); err == nil {
+		t.Error("provider Group shouldn't have been valid")
+	}
+	providerWithInvalidOverrideTo := AlertProvider{
+		Overrides: []Override{
+			{
+				Group: "group",
+				Config: Config{
+					AccessToken:    "",
+					InternalRoomID: "",
+				},
+			},
+		},
+	}
+	if err := providerWithInvalidOverrideTo.Validate(); err == nil {
+		t.Error("provider integration key shouldn't have been valid")
+	}
+	providerWithValidOverride := AlertProvider{
+		DefaultConfig: Config{
+			AccessToken:    "1",
+			InternalRoomID: "!a:example.com",
+		},
+		Overrides: []Override{
+			{
+				Group: "group",
+				Config: Config{
+					ServerURL:      "https://example.com",
+					AccessToken:    "1",
+					InternalRoomID: "!a:example.com",
+				},
+			},
+		},
+	}
+	if err := providerWithValidOverride.Validate(); err != nil {
+		t.Error("provider should've been valid")
+	}
+}
+
+func TestAlertProvider_Send(t *testing.T) {
+	defer client.InjectHTTPClient(nil)
+	firstDescription := "description-1"
+	secondDescription := "description-2"
+	scenarios := []struct {
+		Name             string
+		Provider         AlertProvider
+		Alert            alert.Alert
+		Resolved         bool
+		MockRoundTripper test.MockRoundTripper
+		ExpectedError    bool
+	}{
+		{
+			Name:     "triggered-with-bad-config",
+			Provider: AlertProvider{},
+			Alert:    alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: false,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusOK, Body: http.NoBody}
+			}),
+			ExpectedError: true,
+		},
+		{
+			Name:     "triggered",
+			Provider: AlertProvider{DefaultConfig: Config{AccessToken: "1", InternalRoomID: "!a:example.com"}},
+			Alert:    alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: false,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusOK, Body: http.NoBody}
+			}),
+			ExpectedError: false,
+		},
+		{
+			Name:     "triggered-error",
+			Provider: AlertProvider{DefaultConfig: Config{AccessToken: "1", InternalRoomID: "!a:example.com"}},
+			Alert:    alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: false,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusInternalServerError, Body: http.NoBody}
+			}),
+			ExpectedError: true,
+		},
+		{
+			Name:     "resolved",
+			Provider: AlertProvider{DefaultConfig: Config{AccessToken: "1", InternalRoomID: "!a:example.com"}},
+			Alert:    alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: true,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusOK, Body: http.NoBody}
+			}),
+			ExpectedError: false,
+		},
+		{
+			Name:     "resolved-error",
+			Provider: AlertProvider{DefaultConfig: Config{AccessToken: "1", InternalRoomID: "!a:example.com"}},
+			Alert:    alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: true,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusInternalServerError, Body: http.NoBody}
+			}),
+			ExpectedError: true,
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			client.InjectHTTPClient(&http.Client{Transport: scenario.MockRoundTripper})
+			err := scenario.Provider.Send(
+				&endpoint.Endpoint{Name: "endpoint-name"},
+				&scenario.Alert,
+				&endpoint.Result{
+					ConditionResults: []*endpoint.ConditionResult{
+						{Condition: "[CONNECTED] == true", Success: scenario.Resolved},
+						{Condition: "[STATUS] == 200", Success: scenario.Resolved},
+					},
+				},
+				scenario.Resolved,
+			)
+			if scenario.ExpectedError && err == nil {
+				t.Error("expected error, got none")
+			}
+			if !scenario.ExpectedError && err != nil {
+				t.Error("expected no error, got", err.Error())
+			}
+		})
+	}
+}
+
+func TestAlertProvider_buildRequestBody(t *testing.T) {
+	firstDescription := "description-1"
+	secondDescription := "description-2"
+	scenarios := []struct {
+		Name         string
+		Provider     AlertProvider
+		Alert        alert.Alert
+		Resolved     bool
+		ExpectedBody string
+	}{
+		{
+			Name:         "triggered",
+			Provider:     AlertProvider{},
+			Alert:        alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     false,
+			ExpectedBody: "{\"msgtype\":\"m.text\",\"format\":\"org.matrix.custom.html\",\"body\":\"An alert for `endpoint-name` has been triggered due to having failed 3 time(s) in a row\\ndescription-1\\n\\n✕ - [CONNECTED] == true\\n✕ - [STATUS] == 200\",\"formatted_body\":\"\\u003ch3\\u003eAn alert for \\u003ccode\\u003eendpoint-name\\u003c/code\\u003e has been triggered due to having failed 3 time(s) in a row\\u003c/h3\\u003e\\n\\u003cblockquote\\u003edescription-1\\u003c/blockquote\\u003e\\n\\u003ch5\\u003eCondition results\\u003c/h5\\u003e\\u003cul\\u003e\\u003cli\\u003e❌ - \\u003ccode\\u003e[CONNECTED] == true\\u003c/code\\u003e\\u003c/li\\u003e\\u003cli\\u003e❌ - \\u003ccode\\u003e[STATUS] == 200\\u003c/code\\u003e\\u003c/li\\u003e\\u003c/ul\\u003e\"}",
+		},
+		{
+			Name:         "resolved",
+			Provider:     AlertProvider{},
+			Alert:        alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     true,
+			ExpectedBody: "{\"msgtype\":\"m.text\",\"format\":\"org.matrix.custom.html\",\"body\":\"An alert for `endpoint-name` has been resolved after passing successfully 5 time(s) in a row\\ndescription-2\\n\\n✓ - [CONNECTED] == true\\n✓ - [STATUS] == 200\",\"formatted_body\":\"\\u003ch3\\u003eAn alert for \\u003ccode\\u003eendpoint-name\\u003c/code\\u003e has been resolved after passing successfully 5 time(s) in a row\\u003c/h3\\u003e\\n\\u003cblockquote\\u003edescription-2\\u003c/blockquote\\u003e\\n\\u003ch5\\u003eCondition results\\u003c/h5\\u003e\\u003cul\\u003e\\u003cli\\u003e✅ - \\u003ccode\\u003e[CONNECTED] == true\\u003c/code\\u003e\\u003c/li\\u003e\\u003cli\\u003e✅ - \\u003ccode\\u003e[STATUS] == 200\\u003c/code\\u003e\\u003c/li\\u003e\\u003c/ul\\u003e\"}",
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			body := scenario.Provider.buildRequestBody(
+				&endpoint.Endpoint{Name: "endpoint-name"},
+				&scenario.Alert,
+				&endpoint.Result{
+					ConditionResults: []*endpoint.ConditionResult{
+						{Condition: "[CONNECTED] == true", Success: scenario.Resolved},
+						{Condition: "[STATUS] == 200", Success: scenario.Resolved},
+					},
+				},
+				scenario.Resolved,
+			)
+			if string(body) != scenario.ExpectedBody {
+				t.Errorf("expected:\n%s\ngot:\n%s", scenario.ExpectedBody, body)
+			}
+			out := make(map[string]interface{})
+			if err := json.Unmarshal(body, &out); err != nil {
+				t.Error("expected body to be valid JSON, got error:", err.Error())
+			}
+		})
+	}
+}
+
+func TestAlertProvider_GetDefaultAlert(t *testing.T) {
+	if (&AlertProvider{DefaultAlert: &alert.Alert{}}).GetDefaultAlert() == nil {
+		t.Error("expected default alert to be not nil")
+	}
+	if (&AlertProvider{DefaultAlert: nil}).GetDefaultAlert() != nil {
+		t.Error("expected default alert to be nil")
+	}
+}
+
+func TestAlertProvider_GetConfig(t *testing.T) {
+	scenarios := []struct {
+		Name           string
+		Provider       AlertProvider
+		InputGroup     string
+		InputAlert     alert.Alert
+		ExpectedOutput Config
+	}{
+		{
+			Name: "provider-no-override-specify-no-group-should-default",
+			Provider: AlertProvider{
+				DefaultConfig: Config{
+					ServerURL:      "https://example.com",
+					AccessToken:    "1",
+					InternalRoomID: "!a:example.com",
+				},
+				Overrides: nil,
+			},
+			InputGroup: "",
+			InputAlert: alert.Alert{},
+			ExpectedOutput: Config{
+				ServerURL:      "https://example.com",
+				AccessToken:    "1",
+				InternalRoomID: "!a:example.com",
+			},
+		},
+		{
+			Name: "provider-no-override-specify-group-should-default",
+			Provider: AlertProvider{
+				DefaultConfig: Config{
+					ServerURL:      "https://example.com",
+					AccessToken:    "1",
+					InternalRoomID: "!a:example.com",
+				},
+				Overrides: nil,
+			},
+			InputGroup: "group",
+			InputAlert: alert.Alert{},
+			ExpectedOutput: Config{
+				ServerURL:      "https://example.com",
+				AccessToken:    "1",
+				InternalRoomID: "!a:example.com",
+			},
+		},
+		{
+			Name: "provider-with-override-specify-no-group-should-default",
+			Provider: AlertProvider{
+				DefaultConfig: Config{
+					ServerURL:      "https://example.com",
+					AccessToken:    "1",
+					InternalRoomID: "!a:example.com",
+				},
+				Overrides: []Override{
+					{
+						Group: "group",
+						Config: Config{
+							ServerURL:      "https://group-example.com",
+							AccessToken:    "12",
+							InternalRoomID: "!a:group-example.com",
+						},
+					},
+				},
+			},
+			InputGroup: "",
+			InputAlert: alert.Alert{},
+			ExpectedOutput: Config{
+				ServerURL:      "https://example.com",
+				AccessToken:    "1",
+				InternalRoomID: "!a:example.com",
+			},
+		},
+		{
+			Name: "provider-with-override-specify-group-should-override",
+			Provider: AlertProvider{
+				DefaultConfig: Config{
+					ServerURL:      "https://example.com",
+					AccessToken:    "1",
+					InternalRoomID: "!a:example.com",
+				},
+				Overrides: []Override{
+					{
+						Group: "group",
+						Config: Config{
+							ServerURL:      "https://group-example.com",
+							AccessToken:    "12",
+							InternalRoomID: "!a:group-example.com",
+						},
+					},
+				},
+			},
+			InputGroup: "group",
+			InputAlert: alert.Alert{},
+			ExpectedOutput: Config{
+				ServerURL:      "https://group-example.com",
+				AccessToken:    "12",
+				InternalRoomID: "!a:group-example.com",
+			},
+		},
+		{
+			Name: "provider-with-group-override-and-alert-override--alert-override-should-take-precedence",
+			Provider: AlertProvider{
+				DefaultConfig: Config{
+					ServerURL:      "https://example.com",
+					AccessToken:    "1",
+					InternalRoomID: "!a:example.com",
+				},
+				Overrides: []Override{
+					{
+						Group: "group",
+						Config: Config{
+							ServerURL:      "https://group-example.com",
+							AccessToken:    "12",
+							InternalRoomID: "!a:example01.com",
+						},
+					},
+				},
+			},
+			InputGroup: "group",
+			InputAlert: alert.Alert{ProviderOverride: map[string]any{"server-url": "https://alert-example.com", "access-token": "123", "internal-room-id": "!a:alert-example.com"}},
+			ExpectedOutput: Config{
+				ServerURL:      "https://alert-example.com",
+				AccessToken:    "123",
+				InternalRoomID: "!a:alert-example.com",
+			},
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			outputConfig, err := scenario.Provider.GetConfig(scenario.InputGroup, &scenario.InputAlert)
+			if err != nil {
+				t.Errorf("expected no error, got %v", err)
+			}
+			if outputConfig.ServerURL != scenario.ExpectedOutput.ServerURL {
+				t.Errorf("expected ServerURL to be %s, got %s", scenario.ExpectedOutput.ServerURL, outputConfig.ServerURL)
+			}
+			if outputConfig.AccessToken != scenario.ExpectedOutput.AccessToken {
+				t.Errorf("expected AccessToken to be %s, got %s", scenario.ExpectedOutput.AccessToken, outputConfig.AccessToken)
+			}
+			if outputConfig.InternalRoomID != scenario.ExpectedOutput.InternalRoomID {
+				t.Errorf("expected InternalRoomID to be %s, got %s", scenario.ExpectedOutput.InternalRoomID, outputConfig.InternalRoomID)
+			}
+			// Test ValidateOverrides as well, since it really just calls GetConfig
+			if err = scenario.Provider.ValidateOverrides(scenario.InputGroup, &scenario.InputAlert); err != nil {
+				t.Errorf("unexpected error: %s", err)
+			}
+		})
+	}
+}

alerting/provider/mattermost/mattermost.go

@@ -0,0 +1,211 @@
+package mattermost
+
+import (
+	"bytes"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+
+	"github.com/TwiN/gatus/v5/alerting/alert"
+	"github.com/TwiN/gatus/v5/client"
+	"github.com/TwiN/gatus/v5/config/endpoint"
+	"gopkg.in/yaml.v3"
+)
+
+var (
+	ErrWebhookURLNotSet       = errors.New("webhook URL not set")
+	ErrDuplicateGroupOverride = errors.New("duplicate group override")
+)
+
+type Config struct {
+	WebhookURL   string         `yaml:"webhook-url"`
+	Channel      string         `yaml:"channel,omitempty"`
+	ClientConfig *client.Config `yaml:"client,omitempty"`
+}
+
+func (cfg *Config) Validate() error {
+	if len(cfg.WebhookURL) == 0 {
+		return ErrWebhookURLNotSet
+	}
+	return nil
+}
+
+func (cfg *Config) Merge(override *Config) {
+	if override.ClientConfig != nil {
+		cfg.ClientConfig = override.ClientConfig
+	}
+	if len(override.WebhookURL) > 0 {
+		cfg.WebhookURL = override.WebhookURL
+	}
+	if len(override.Channel) > 0 {
+		cfg.Channel = override.Channel
+	}
+}
+
+// AlertProvider is the configuration necessary for sending an alert using Mattermost
+type AlertProvider struct {
+	DefaultConfig Config `yaml:",inline"`
+
+	// DefaultAlert is the default alert configuration to use for endpoints with an alert of the appropriate type
+	DefaultAlert *alert.Alert `yaml:"default-alert,omitempty"`
+
+	// Overrides is a list of Override that may be prioritized over the default configuration
+	Overrides []Override `yaml:"overrides,omitempty"`
+}
+
+// Override is a case under which the default integration is overridden
+type Override struct {
+	Group  string `yaml:"group"`
+	Config `yaml:",inline"`
+}
+
+// Validate the provider's configuration
+func (provider *AlertProvider) Validate() error {
+	if provider.Overrides != nil {
+		registeredGroups := make(map[string]bool)
+		for _, override := range provider.Overrides {
+			if isAlreadyRegistered := registeredGroups[override.Group]; isAlreadyRegistered || override.Group == "" || len(override.WebhookURL) == 0 {
+				return ErrDuplicateGroupOverride
+			}
+			registeredGroups[override.Group] = true
+		}
+	}
+	return provider.DefaultConfig.Validate()
+}
+
+// Send an alert using the provider
+func (provider *AlertProvider) Send(ep *endpoint.Endpoint, alert *alert.Alert, result *endpoint.Result, resolved bool) error {
+	cfg, err := provider.GetConfig(ep.Group, alert)
+	if err != nil {
+		return err
+	}
+	buffer := bytes.NewBuffer([]byte(provider.buildRequestBody(cfg, ep, alert, result, resolved)))
+	request, err := http.NewRequest(http.MethodPost, cfg.WebhookURL, buffer)
+	if err != nil {
+		return err
+	}
+	request.Header.Set("Content-Type", "application/json")
+	response, err := client.GetHTTPClient(cfg.ClientConfig).Do(request)
+	if err != nil {
+		return err
+	}
+	defer response.Body.Close()
+	if response.StatusCode > 399 {
+		body, _ := io.ReadAll(response.Body)
+		return fmt.Errorf("call to provider alert returned status code %d: %s", response.StatusCode, string(body))
+	}
+	return err
+}
+
+type Body struct {
+	Channel     string       `json:"channel,omitempty"` // Optional channel override
+	Text        string       `json:"text"`
+	Username    string       `json:"username"`
+	IconURL     string       `json:"icon_url"`
+	Attachments []Attachment `json:"attachments"`
+}
+
+type Attachment struct {
+	Title    string  `json:"title"`
+	Fallback string  `json:"fallback"`
+	Text     string  `json:"text"`
+	Short    bool    `json:"short"`
+	Color    string  `json:"color"`
+	Fields   []Field `json:"fields"`
+}
+
+type Field struct {
+	Title string `json:"title"`
+	Value string `json:"value"`
+	Short bool   `json:"short"`
+}
+
+// buildRequestBody builds the request body for the provider
+func (provider *AlertProvider) buildRequestBody(cfg *Config, ep *endpoint.Endpoint, alert *alert.Alert, result *endpoint.Result, resolved bool) []byte {
+	var message, color string
+	if resolved {
+		message = fmt.Sprintf("An alert for *%s* has been resolved after passing successfully %d time(s) in a row", ep.DisplayName(), alert.SuccessThreshold)
+		color = "#36A64F"
+	} else {
+		message = fmt.Sprintf("An alert for *%s* has been triggered due to having failed %d time(s) in a row", ep.DisplayName(), alert.FailureThreshold)
+		color = "#DD0000"
+	}
+	var formattedConditionResults string
+	if len(result.ConditionResults) > 0 {
+		for _, conditionResult := range result.ConditionResults {
+			var prefix string
+			if conditionResult.Success {
+				prefix = ":white_check_mark:"
+			} else {
+				prefix = ":x:"
+			}
+			formattedConditionResults += fmt.Sprintf("%s - `%s`\n", prefix, conditionResult.Condition)
+		}
+	}
+	var description string
+	if alertDescription := alert.GetDescription(); len(alertDescription) > 0 {
+		description = ":\n> " + alertDescription
+	}
+	body := Body{
+		Channel:  cfg.Channel,
+		Text:     "",
+		Username: "gatus",
+		IconURL:  "https://raw.githubusercontent.com/TwiN/gatus/master/.github/assets/logo.png",
+		Attachments: []Attachment{
+			{
+				Title:    ":helmet_with_white_cross: Gatus",
+				Fallback: "Gatus - " + message,
+				Text:     message + description,
+				Short:    false,
+				Color:    color,
+			},
+		},
+	}
+	if len(formattedConditionResults) > 0 {
+		body.Attachments[0].Fields = append(body.Attachments[0].Fields, Field{
+			Title: "Condition results",
+			Value: formattedConditionResults,
+			Short: false,
+		})
+	}
+	bodyAsJSON, _ := json.Marshal(body)
+	return bodyAsJSON
+}
+
+// GetDefaultAlert returns the provider's default alert configuration
+func (provider *AlertProvider) GetDefaultAlert() *alert.Alert {
+	return provider.DefaultAlert
+}
+
+// GetConfig returns the configuration for the provider with the overrides applied
+func (provider *AlertProvider) GetConfig(group string, alert *alert.Alert) (*Config, error) {
+	cfg := provider.DefaultConfig
+	// Handle group overrides
+	if provider.Overrides != nil {
+		for _, override := range provider.Overrides {
+			if group == override.Group {
+				cfg.Merge(&override.Config)
+				break
+			}
+		}
+	}
+	// Handle alert overrides
+	if len(alert.ProviderOverride) != 0 {
+		overrideConfig := Config{}
+		if err := yaml.Unmarshal(alert.ProviderOverrideAsBytes(), &overrideConfig); err != nil {
+			return nil, err
+		}
+		cfg.Merge(&overrideConfig)
+	}
+	// Validate the configuration
+	err := cfg.Validate()
+	return &cfg, err
+}
+
+// ValidateOverrides validates the alert's provider override and, if present, the group override
+func (provider *AlertProvider) ValidateOverrides(group string, alert *alert.Alert) error {
+	_, err := provider.GetConfig(group, alert)
+	return err
+}

alerting/provider/mattermost/mattermost_test.go

@@ -0,0 +1,287 @@
+package mattermost
+
+import (
+	"encoding/json"
+	"net/http"
+	"testing"
+
+	"github.com/TwiN/gatus/v5/alerting/alert"
+	"github.com/TwiN/gatus/v5/client"
+	"github.com/TwiN/gatus/v5/config/endpoint"
+	"github.com/TwiN/gatus/v5/test"
+)
+
+func TestAlertProvider_Validate(t *testing.T) {
+	invalidProvider := AlertProvider{DefaultConfig: Config{WebhookURL: ""}}
+	if err := invalidProvider.Validate(); err == nil {
+		t.Error("provider shouldn't have been valid")
+	}
+	validProvider := AlertProvider{DefaultConfig: Config{WebhookURL: "http://example.com"}}
+	if err := validProvider.Validate(); err != nil {
+		t.Error("provider should've been valid")
+	}
+}
+
+func TestAlertProvider_ValidateWithOverride(t *testing.T) {
+	providerWithInvalidOverrideGroup := AlertProvider{
+		Overrides: []Override{
+			{
+				Config: Config{WebhookURL: "http://example.com"},
+				Group:  "",
+			},
+		},
+	}
+	if err := providerWithInvalidOverrideGroup.Validate(); err == nil {
+		t.Error("provider Group shouldn't have been valid")
+	}
+	providerWithInvalidOverrideWebHookUrl := AlertProvider{
+		Overrides: []Override{
+			{
+				Config: Config{WebhookURL: ""},
+				Group:  "group",
+			},
+		},
+	}
+	if err := providerWithInvalidOverrideWebHookUrl.Validate(); err == nil {
+		t.Error("provider WebHookURL shouldn't have been valid")
+	}
+	providerWithValidOverride := AlertProvider{
+		DefaultConfig: Config{WebhookURL: "http://example.com"},
+		Overrides: []Override{
+			{
+				Config: Config{WebhookURL: "http://example.com"},
+				Group:  "group",
+			},
+		},
+	}
+	if err := providerWithValidOverride.Validate(); err != nil {
+		t.Error("provider should've been valid")
+	}
+}
+
+func TestAlertProvider_Send(t *testing.T) {
+	defer client.InjectHTTPClient(nil)
+	firstDescription := "description-1"
+	secondDescription := "description-2"
+	scenarios := []struct {
+		Name             string
+		Provider         AlertProvider
+		Alert            alert.Alert
+		Resolved         bool
+		MockRoundTripper test.MockRoundTripper
+		ExpectedError    bool
+	}{
+		{
+			Name:     "triggered",
+			Provider: AlertProvider{DefaultConfig: Config{WebhookURL: "http://example.com"}},
+			Alert:    alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: false,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusOK, Body: http.NoBody}
+			}),
+			ExpectedError: false,
+		},
+		{
+			Name:     "triggered-error",
+			Provider: AlertProvider{DefaultConfig: Config{WebhookURL: "http://example.com"}},
+			Alert:    alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: false,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusInternalServerError, Body: http.NoBody}
+			}),
+			ExpectedError: true,
+		},
+		{
+			Name:     "resolved",
+			Provider: AlertProvider{DefaultConfig: Config{WebhookURL: "http://example.com"}},
+			Alert:    alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: true,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusOK, Body: http.NoBody}
+			}),
+			ExpectedError: false,
+		},
+		{
+			Name:     "resolved-error",
+			Provider: AlertProvider{DefaultConfig: Config{WebhookURL: "http://example.com"}},
+			Alert:    alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: true,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusInternalServerError, Body: http.NoBody}
+			}),
+			ExpectedError: true,
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			client.InjectHTTPClient(&http.Client{Transport: scenario.MockRoundTripper})
+			err := scenario.Provider.Send(
+				&endpoint.Endpoint{Name: "endpoint-name"},
+				&scenario.Alert,
+				&endpoint.Result{
+					ConditionResults: []*endpoint.ConditionResult{
+						{Condition: "[CONNECTED] == true", Success: scenario.Resolved},
+						{Condition: "[STATUS] == 200", Success: scenario.Resolved},
+					},
+				},
+				scenario.Resolved,
+			)
+			if scenario.ExpectedError && err == nil {
+				t.Error("expected error, got none")
+			}
+			if !scenario.ExpectedError && err != nil {
+				t.Error("expected no error, got", err.Error())
+			}
+		})
+	}
+}
+
+func TestAlertProvider_buildRequestBody(t *testing.T) {
+	firstDescription := "description-1"
+	secondDescription := "description-2"
+	scenarios := []struct {
+		Name         string
+		Provider     AlertProvider
+		Alert        alert.Alert
+		Resolved     bool
+		ExpectedBody string
+	}{
+		{
+			Name:         "triggered",
+			Provider:     AlertProvider{},
+			Alert:        alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     false,
+			ExpectedBody: "{\"text\":\"\",\"username\":\"gatus\",\"icon_url\":\"https://raw.githubusercontent.com/TwiN/gatus/master/.github/assets/logo.png\",\"attachments\":[{\"title\":\":helmet_with_white_cross: Gatus\",\"fallback\":\"Gatus - An alert for *endpoint-name* has been triggered due to having failed 3 time(s) in a row\",\"text\":\"An alert for *endpoint-name* has been triggered due to having failed 3 time(s) in a row:\\n\\u003e description-1\",\"short\":false,\"color\":\"#DD0000\",\"fields\":[{\"title\":\"Condition results\",\"value\":\":x: - `[CONNECTED] == true`\\n:x: - `[STATUS] == 200`\\n\",\"short\":false}]}]}",
+		},
+		{
+			Name:         "resolved",
+			Provider:     AlertProvider{},
+			Alert:        alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     true,
+			ExpectedBody: "{\"text\":\"\",\"username\":\"gatus\",\"icon_url\":\"https://raw.githubusercontent.com/TwiN/gatus/master/.github/assets/logo.png\",\"attachments\":[{\"title\":\":helmet_with_white_cross: Gatus\",\"fallback\":\"Gatus - An alert for *endpoint-name* has been resolved after passing successfully 5 time(s) in a row\",\"text\":\"An alert for *endpoint-name* has been resolved after passing successfully 5 time(s) in a row:\\n\\u003e description-2\",\"short\":false,\"color\":\"#36A64F\",\"fields\":[{\"title\":\"Condition results\",\"value\":\":white_check_mark: - `[CONNECTED] == true`\\n:white_check_mark: - `[STATUS] == 200`\\n\",\"short\":false}]}]}",
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			body := scenario.Provider.buildRequestBody(
+				&scenario.Provider.DefaultConfig,
+				&endpoint.Endpoint{Name: "endpoint-name"},
+				&scenario.Alert,
+				&endpoint.Result{
+					ConditionResults: []*endpoint.ConditionResult{
+						{Condition: "[CONNECTED] == true", Success: scenario.Resolved},
+						{Condition: "[STATUS] == 200", Success: scenario.Resolved},
+					},
+				},
+				scenario.Resolved,
+			)
+			if string(body) != scenario.ExpectedBody {
+				t.Errorf("expected:\n%s\ngot:\n%s", scenario.ExpectedBody, body)
+			}
+			out := make(map[string]interface{})
+			if err := json.Unmarshal(body, &out); err != nil {
+				t.Error("expected body to be valid JSON, got error:", err.Error())
+			}
+		})
+	}
+}
+
+func TestAlertProvider_GetDefaultAlert(t *testing.T) {
+	if (&AlertProvider{DefaultAlert: &alert.Alert{}}).GetDefaultAlert() == nil {
+		t.Error("expected default alert to be not nil")
+	}
+	if (&AlertProvider{DefaultAlert: nil}).GetDefaultAlert() != nil {
+		t.Error("expected default alert to be nil")
+	}
+}
+
+func TestAlertProvider_GetConfig(t *testing.T) {
+	scenarios := []struct {
+		Name           string
+		Provider       AlertProvider
+		InputGroup     string
+		InputAlert     alert.Alert
+		ExpectedOutput Config
+	}{
+		{
+			Name: "provider-no-override-specify-no-group-should-default",
+			Provider: AlertProvider{
+				DefaultConfig: Config{WebhookURL: "http://example.com"},
+				Overrides:     nil,
+			},
+			InputGroup:     "",
+			InputAlert:     alert.Alert{},
+			ExpectedOutput: Config{WebhookURL: "http://example.com"},
+		},
+		{
+			Name: "provider-no-override-specify-group-should-default",
+			Provider: AlertProvider{
+				DefaultConfig: Config{WebhookURL: "http://example.com"},
+				Overrides:     nil,
+			},
+			InputGroup:     "group",
+			InputAlert:     alert.Alert{},
+			ExpectedOutput: Config{WebhookURL: "http://example.com"},
+		},
+		{
+			Name: "provider-with-override-specify-no-group-should-default",
+			Provider: AlertProvider{
+				DefaultConfig: Config{WebhookURL: "http://example.com"},
+				Overrides: []Override{
+					{
+						Group:  "group",
+						Config: Config{WebhookURL: "http://example01.com"},
+					},
+				},
+			},
+			InputGroup:     "",
+			InputAlert:     alert.Alert{},
+			ExpectedOutput: Config{WebhookURL: "http://example.com"},
+		},
+		{
+			Name: "provider-with-override-specify-group-should-override",
+			Provider: AlertProvider{
+				DefaultConfig: Config{WebhookURL: "http://example.com"},
+				Overrides: []Override{
+					{
+						Group:  "group",
+						Config: Config{WebhookURL: "http://group-example.com"},
+					},
+				},
+			},
+			InputGroup:     "group",
+			InputAlert:     alert.Alert{},
+			ExpectedOutput: Config{WebhookURL: "http://group-example.com"},
+		},
+		{
+			Name: "provider-with-group-override-and-alert-override--alert-override-should-take-precedence",
+			Provider: AlertProvider{
+				DefaultConfig: Config{WebhookURL: "http://example.com"},
+				Overrides: []Override{
+					{
+						Group:  "group",
+						Config: Config{WebhookURL: "http://group-example.com"},
+					},
+				},
+			},
+			InputGroup:     "group",
+			InputAlert:     alert.Alert{ProviderOverride: map[string]any{"webhook-url": "http://alert-example.com"}},
+			ExpectedOutput: Config{WebhookURL: "http://alert-example.com"},
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			got, err := scenario.Provider.GetConfig(scenario.InputGroup, &scenario.InputAlert)
+			if err != nil {
+				t.Fatalf("unexpected error: %s", err)
+			}
+			if got.WebhookURL != scenario.ExpectedOutput.WebhookURL {
+				t.Errorf("expected webhook URL to be %s, got %s", scenario.ExpectedOutput.WebhookURL, got.WebhookURL)
+			}
+			// Test ValidateOverrides as well, since it really just calls GetConfig
+			if err = scenario.Provider.ValidateOverrides(scenario.InputGroup, &scenario.InputAlert); err != nil {
+				t.Errorf("unexpected error: %s", err)
+			}
+		})
+	}
+}

alerting/provider/messagebird/messagebird.go

@@ -0,0 +1,142 @@
+package messagebird
+
+import (
+	"bytes"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+
+	"github.com/TwiN/gatus/v5/alerting/alert"
+	"github.com/TwiN/gatus/v5/client"
+	"github.com/TwiN/gatus/v5/config/endpoint"
+	"gopkg.in/yaml.v3"
+)
+
+const restAPIURL = "https://rest.messagebird.com/messages"
+
+var (
+	ErrorAccessKeyNotSet  = errors.New("access-key not set")
+	ErrorOriginatorNotSet = errors.New("originator not set")
+	ErrorRecipientsNotSet = errors.New("recipients not set")
+)
+
+type Config struct {
+	AccessKey  string `yaml:"access-key"`
+	Originator string `yaml:"originator"`
+	Recipients string `yaml:"recipients"`
+}
+
+func (cfg *Config) Validate() error {
+	if len(cfg.AccessKey) == 0 {
+		return ErrorAccessKeyNotSet
+	}
+	if len(cfg.Originator) == 0 {
+		return ErrorOriginatorNotSet
+	}
+	if len(cfg.Recipients) == 0 {
+		return ErrorRecipientsNotSet
+	}
+	return nil
+}
+
+func (cfg *Config) Merge(override *Config) {
+	if len(override.AccessKey) > 0 {
+		cfg.AccessKey = override.AccessKey
+	}
+	if len(override.Originator) > 0 {
+		cfg.Originator = override.Originator
+	}
+	if len(override.Recipients) > 0 {
+		cfg.Recipients = override.Recipients
+	}
+}
+
+// AlertProvider is the configuration necessary for sending an alert using Messagebird
+type AlertProvider struct {
+	DefaultConfig Config `yaml:",inline"`
+
+	// DefaultAlert is the default alert configuration to use for endpoints with an alert of the appropriate type
+	DefaultAlert *alert.Alert `yaml:"default-alert,omitempty"`
+}
+
+// Validate the provider's configuration
+func (provider *AlertProvider) Validate() error {
+	return provider.DefaultConfig.Validate()
+}
+
+// Send an alert using the provider
+// Reference doc for messagebird: https://developers.messagebird.com/api/sms-messaging/#send-outbound-sms
+func (provider *AlertProvider) Send(ep *endpoint.Endpoint, alert *alert.Alert, result *endpoint.Result, resolved bool) error {
+	cfg, err := provider.GetConfig(ep.Group, alert)
+	if err != nil {
+		return err
+	}
+	buffer := bytes.NewBuffer(provider.buildRequestBody(cfg, ep, alert, result, resolved))
+	request, err := http.NewRequest(http.MethodPost, restAPIURL, buffer)
+	if err != nil {
+		return err
+	}
+	request.Header.Set("Content-Type", "application/json")
+	request.Header.Set("Authorization", fmt.Sprintf("AccessKey %s", cfg.AccessKey))
+	response, err := client.GetHTTPClient(nil).Do(request)
+	if err != nil {
+		return err
+	}
+	defer response.Body.Close()
+	if response.StatusCode > 399 {
+		body, _ := io.ReadAll(response.Body)
+		return fmt.Errorf("call to provider alert returned status code %d: %s", response.StatusCode, string(body))
+	}
+	return err
+}
+
+type Body struct {
+	Originator string `json:"originator"`
+	Recipients string `json:"recipients"`
+	Body       string `json:"body"`
+}
+
+// buildRequestBody builds the request body for the provider
+func (provider *AlertProvider) buildRequestBody(cfg *Config, ep *endpoint.Endpoint, alert *alert.Alert, result *endpoint.Result, resolved bool) []byte {
+	var message string
+	if resolved {
+		message = fmt.Sprintf("RESOLVED: %s - %s", ep.DisplayName(), alert.GetDescription())
+	} else {
+		message = fmt.Sprintf("TRIGGERED: %s - %s", ep.DisplayName(), alert.GetDescription())
+	}
+	body, _ := json.Marshal(Body{
+		Originator: cfg.Originator,
+		Recipients: cfg.Recipients,
+		Body:       message,
+	})
+	return body
+}
+
+// GetDefaultAlert returns the provider's default alert configuration
+func (provider *AlertProvider) GetDefaultAlert() *alert.Alert {
+	return provider.DefaultAlert
+}
+
+// GetConfig returns the configuration for the provider with the overrides applied
+func (provider *AlertProvider) GetConfig(group string, alert *alert.Alert) (*Config, error) {
+	cfg := provider.DefaultConfig
+	// Handle alert overrides
+	if len(alert.ProviderOverride) != 0 {
+		overrideConfig := Config{}
+		if err := yaml.Unmarshal(alert.ProviderOverrideAsBytes(), &overrideConfig); err != nil {
+			return nil, err
+		}
+		cfg.Merge(&overrideConfig)
+	}
+	// Validate the configuration
+	err := cfg.Validate()
+	return &cfg, err
+}
+
+// ValidateOverrides validates the alert's provider override and, if present, the group override
+func (provider *AlertProvider) ValidateOverrides(group string, alert *alert.Alert) error {
+	_, err := provider.GetConfig(group, alert)
+	return err
+}

alerting/provider/messagebird/messagebird_test.go

@@ -0,0 +1,212 @@
+package messagebird
+
+import (
+	"encoding/json"
+	"net/http"
+	"testing"
+
+	"github.com/TwiN/gatus/v5/alerting/alert"
+	"github.com/TwiN/gatus/v5/client"
+	"github.com/TwiN/gatus/v5/config/endpoint"
+	"github.com/TwiN/gatus/v5/test"
+)
+
+func TestMessagebirdAlertProvider_IsValid(t *testing.T) {
+	invalidProvider := AlertProvider{}
+	if err := invalidProvider.Validate(); err == nil {
+		t.Error("provider shouldn't have been valid")
+	}
+	validProvider := AlertProvider{
+		DefaultConfig: Config{
+			AccessKey:  "1",
+			Originator: "1",
+			Recipients: "1",
+		},
+	}
+	if err := validProvider.Validate(); err != nil {
+		t.Error("provider should've been valid")
+	}
+}
+
+func TestAlertProvider_Send(t *testing.T) {
+	defer client.InjectHTTPClient(nil)
+	firstDescription := "description-1"
+	secondDescription := "description-2"
+	scenarios := []struct {
+		Name             string
+		Provider         AlertProvider
+		Alert            alert.Alert
+		Resolved         bool
+		MockRoundTripper test.MockRoundTripper
+		ExpectedError    bool
+	}{
+		{
+			Name:     "triggered",
+			Provider: AlertProvider{DefaultConfig: Config{AccessKey: "1", Originator: "2", Recipients: "3"}},
+			Alert:    alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: false,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusOK, Body: http.NoBody}
+			}),
+			ExpectedError: false,
+		},
+		{
+			Name:     "triggered-error",
+			Provider: AlertProvider{DefaultConfig: Config{AccessKey: "1", Originator: "2", Recipients: "3"}},
+			Alert:    alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: false,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusInternalServerError, Body: http.NoBody}
+			}),
+			ExpectedError: true,
+		},
+		{
+			Name:     "resolved",
+			Provider: AlertProvider{DefaultConfig: Config{AccessKey: "1", Originator: "2", Recipients: "3"}},
+			Alert:    alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: true,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusOK, Body: http.NoBody}
+			}),
+			ExpectedError: false,
+		},
+		{
+			Name:     "resolved-error",
+			Provider: AlertProvider{DefaultConfig: Config{AccessKey: "1", Originator: "2", Recipients: "3"}},
+			Alert:    alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: true,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusInternalServerError, Body: http.NoBody}
+			}),
+			ExpectedError: true,
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			client.InjectHTTPClient(&http.Client{Transport: scenario.MockRoundTripper})
+			err := scenario.Provider.Send(
+				&endpoint.Endpoint{Name: "endpoint-name"},
+				&scenario.Alert,
+				&endpoint.Result{
+					ConditionResults: []*endpoint.ConditionResult{
+						{Condition: "[CONNECTED] == true", Success: scenario.Resolved},
+						{Condition: "[STATUS] == 200", Success: scenario.Resolved},
+					},
+				},
+				scenario.Resolved,
+			)
+			if scenario.ExpectedError && err == nil {
+				t.Error("expected error, got none")
+			}
+			if !scenario.ExpectedError && err != nil {
+				t.Error("expected no error, got", err.Error())
+			}
+		})
+	}
+}
+
+func TestAlertProvider_buildRequestBody(t *testing.T) {
+	firstDescription := "description-1"
+	secondDescription := "description-2"
+	scenarios := []struct {
+		Name         string
+		Provider     AlertProvider
+		Alert        alert.Alert
+		Resolved     bool
+		ExpectedBody string
+	}{
+		{
+			Name:         "triggered",
+			Provider:     AlertProvider{DefaultConfig: Config{AccessKey: "1", Originator: "2", Recipients: "3"}},
+			Alert:        alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     false,
+			ExpectedBody: "{\"originator\":\"2\",\"recipients\":\"3\",\"body\":\"TRIGGERED: endpoint-name - description-1\"}",
+		},
+		{
+			Name:         "resolved",
+			Provider:     AlertProvider{DefaultConfig: Config{AccessKey: "4", Originator: "5", Recipients: "6"}},
+			Alert:        alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     true,
+			ExpectedBody: "{\"originator\":\"5\",\"recipients\":\"6\",\"body\":\"RESOLVED: endpoint-name - description-2\"}",
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			body := scenario.Provider.buildRequestBody(
+				&scenario.Provider.DefaultConfig,
+				&endpoint.Endpoint{Name: "endpoint-name"},
+				&scenario.Alert,
+				&endpoint.Result{
+					ConditionResults: []*endpoint.ConditionResult{
+						{Condition: "[CONNECTED] == true", Success: scenario.Resolved},
+						{Condition: "[STATUS] == 200", Success: scenario.Resolved},
+					},
+				},
+				scenario.Resolved,
+			)
+			if string(body) != scenario.ExpectedBody {
+				t.Errorf("expected:\n%s\ngot:\n%s", scenario.ExpectedBody, body)
+			}
+			out := make(map[string]interface{})
+			if err := json.Unmarshal(body, &out); err != nil {
+				t.Error("expected body to be valid JSON, got error:", err.Error())
+			}
+		})
+	}
+}
+
+func TestAlertProvider_GetDefaultAlert(t *testing.T) {
+	if (&AlertProvider{DefaultAlert: &alert.Alert{}}).GetDefaultAlert() == nil {
+		t.Error("expected default alert to be not nil")
+	}
+	if (&AlertProvider{DefaultAlert: nil}).GetDefaultAlert() != nil {
+		t.Error("expected default alert to be nil")
+	}
+}
+
+func TestAlertProvider_GetConfig(t *testing.T) {
+	scenarios := []struct {
+		Name           string
+		Provider       AlertProvider
+		InputAlert     alert.Alert
+		ExpectedOutput Config
+	}{
+		{
+			Name: "provider-no-override-should-default",
+			Provider: AlertProvider{
+				DefaultConfig: Config{AccessKey: "1", Originator: "2", Recipients: "3"},
+			},
+			InputAlert:     alert.Alert{},
+			ExpectedOutput: Config{AccessKey: "1", Originator: "2", Recipients: "3"},
+		},
+		{
+			Name: "provider-with-alert-override",
+			Provider: AlertProvider{
+				DefaultConfig: Config{AccessKey: "1", Originator: "2", Recipients: "3"},
+			},
+			InputAlert:     alert.Alert{ProviderOverride: map[string]any{"access-key": "4", "originator": "5", "recipients": "6"}},
+			ExpectedOutput: Config{AccessKey: "4", Originator: "5", Recipients: "6"},
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			got, err := scenario.Provider.GetConfig("", &scenario.InputAlert)
+			if err != nil {
+				t.Error("expected no error, got:", err.Error())
+			}
+			if got.AccessKey != scenario.ExpectedOutput.AccessKey {
+				t.Errorf("expected access key to be %s, got %s", scenario.ExpectedOutput.AccessKey, got.AccessKey)
+			}
+			if got.Originator != scenario.ExpectedOutput.Originator {
+				t.Errorf("expected originator to be %s, got %s", scenario.ExpectedOutput.Originator, got.Originator)
+			}
+			if got.Recipients != scenario.ExpectedOutput.Recipients {
+				t.Errorf("expected recipients to be %s, got %s", scenario.ExpectedOutput.Recipients, got.Recipients)
+			}
+			// Test ValidateOverrides as well, since it really just calls GetConfig
+			if err = scenario.Provider.ValidateOverrides("", &scenario.InputAlert); err != nil {
+				t.Errorf("unexpected error: %s", err)
+			}
+		})
+	}
+}

alerting/provider/ntfy/ntfy.go

@@ -0,0 +1,243 @@
+package ntfy
+
+import (
+	"bytes"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+	"strconv"
+	"strings"
+
+	"github.com/TwiN/gatus/v5/alerting/alert"
+	"github.com/TwiN/gatus/v5/client"
+	"github.com/TwiN/gatus/v5/config/endpoint"
+	"gopkg.in/yaml.v3"
+)
+
+const (
+	DefaultURL      = "https://ntfy.sh"
+	DefaultPriority = 3
+	TokenPrefix     = "tk_"
+)
+
+var (
+	ErrInvalidToken           = errors.New("invalid token")
+	ErrTopicNotSet            = errors.New("topic not set")
+	ErrInvalidPriority        = errors.New("priority must between 1 and 5 inclusively")
+	ErrDuplicateGroupOverride = errors.New("duplicate group override")
+)
+
+type Config struct {
+	Topic           string `yaml:"topic"`
+	URL             string `yaml:"url,omitempty"`              // Defaults to DefaultURL
+	Priority        int    `yaml:"priority,omitempty"`         // Defaults to DefaultPriority
+	Token           string `yaml:"token,omitempty"`            // Defaults to ""
+	Email           string `yaml:"email,omitempty"`            // Defaults to ""
+	Click           string `yaml:"click,omitempty"`            // Defaults to ""
+	DisableFirebase bool   `yaml:"disable-firebase,omitempty"` // Defaults to false
+	DisableCache    bool   `yaml:"disable-cache,omitempty"`    // Defaults to false
+}
+
+func (cfg *Config) Validate() error {
+	if len(cfg.URL) == 0 {
+		cfg.URL = DefaultURL
+	}
+	if cfg.Priority == 0 {
+		cfg.Priority = DefaultPriority
+	}
+	if len(cfg.Token) > 0 && !strings.HasPrefix(cfg.Token, TokenPrefix) {
+		return ErrInvalidToken
+	}
+	if len(cfg.Topic) == 0 {
+		return ErrTopicNotSet
+	}
+	if cfg.Priority < 1 || cfg.Priority > 5 {
+		return ErrInvalidPriority
+	}
+	return nil
+}
+
+func (cfg *Config) Merge(override *Config) {
+	if len(override.Topic) > 0 {
+		cfg.Topic = override.Topic
+	}
+	if len(override.URL) > 0 {
+		cfg.URL = override.URL
+	}
+	if override.Priority > 0 {
+		cfg.Priority = override.Priority
+	}
+	if len(override.Token) > 0 {
+		cfg.Token = override.Token
+	}
+	if len(override.Email) > 0 {
+		cfg.Email = override.Email
+	}
+	if len(override.Click) > 0 {
+		cfg.Click = override.Click
+	}
+	if override.DisableFirebase {
+		cfg.DisableFirebase = true
+	}
+	if override.DisableCache {
+		cfg.DisableCache = true
+	}
+}
+
+// AlertProvider is the configuration necessary for sending an alert using Slack
+type AlertProvider struct {
+	DefaultConfig Config `yaml:",inline"`
+
+	// DefaultAlert is the default alert configuration to use for endpoints with an alert of the appropriate type
+	DefaultAlert *alert.Alert `yaml:"default-alert,omitempty"`
+
+	// Overrides is a list of Override that may be prioritized over the default configuration
+	Overrides []Override `yaml:"overrides,omitempty"`
+}
+
+// Override is a case under which the default integration is overridden
+type Override struct {
+	Group  string `yaml:"group"`
+	Config `yaml:",inline"`
+}
+
+// Validate the provider's configuration
+func (provider *AlertProvider) Validate() error {
+	registeredGroups := make(map[string]bool)
+	if provider.Overrides != nil {
+		for _, override := range provider.Overrides {
+			if len(override.Group) == 0 {
+				return ErrDuplicateGroupOverride
+			}
+			if _, ok := registeredGroups[override.Group]; ok {
+				return ErrDuplicateGroupOverride
+			}
+			if len(override.Token) > 0 && !strings.HasPrefix(override.Token, TokenPrefix) {
+				return ErrDuplicateGroupOverride
+			}
+			if override.Priority < 0 || override.Priority >= 6 {
+				return ErrDuplicateGroupOverride
+			}
+			registeredGroups[override.Group] = true
+		}
+	}
+
+	return provider.DefaultConfig.Validate()
+}
+
+// Send an alert using the provider
+func (provider *AlertProvider) Send(ep *endpoint.Endpoint, alert *alert.Alert, result *endpoint.Result, resolved bool) error {
+	cfg, err := provider.GetConfig(ep.Group, alert)
+	if err != nil {
+		return err
+	}
+	buffer := bytes.NewBuffer(provider.buildRequestBody(cfg, ep, alert, result, resolved))
+	url := cfg.URL
+	request, err := http.NewRequest(http.MethodPost, url, buffer)
+	if err != nil {
+		return err
+	}
+	request.Header.Set("Content-Type", "application/json")
+	if token := cfg.Token; len(token) > 0 {
+		request.Header.Set("Authorization", "Bearer "+token)
+	}
+	if cfg.DisableFirebase {
+		request.Header.Set("Firebase", "no")
+	}
+	if cfg.DisableCache {
+		request.Header.Set("Cache", "no")
+	}
+	response, err := client.GetHTTPClient(nil).Do(request)
+	if err != nil {
+		return err
+	}
+	defer response.Body.Close()
+	if response.StatusCode > 399 {
+		body, _ := io.ReadAll(response.Body)
+		return fmt.Errorf("call to provider alert returned status code %d: %s", response.StatusCode, string(body))
+	}
+	return err
+}
+
+type Body struct {
+	Topic    string   `json:"topic"`
+	Title    string   `json:"title"`
+	Message  string   `json:"message"`
+	Tags     []string `json:"tags"`
+	Priority int      `json:"priority"`
+	Email    string   `json:"email,omitempty"`
+	Click    string   `json:"click,omitempty"`
+}
+
+// buildRequestBody builds the request body for the provider
+func (provider *AlertProvider) buildRequestBody(cfg *Config, ep *endpoint.Endpoint, alert *alert.Alert, result *endpoint.Result, resolved bool) []byte {
+	var message, formattedConditionResults, tag string
+	if resolved {
+		tag = "white_check_mark"
+		message = "An alert has been resolved after passing successfully " + strconv.Itoa(alert.SuccessThreshold) + " time(s) in a row"
+	} else {
+		tag = "rotating_light"
+		message = "An alert has been triggered due to having failed " + strconv.Itoa(alert.FailureThreshold) + " time(s) in a row"
+	}
+	for _, conditionResult := range result.ConditionResults {
+		var prefix string
+		if conditionResult.Success {
+			prefix = "🟢"
+		} else {
+			prefix = "🔴"
+		}
+		formattedConditionResults += fmt.Sprintf("\n%s %s", prefix, conditionResult.Condition)
+	}
+	if len(alert.GetDescription()) > 0 {
+		message += " with the following description: " + alert.GetDescription()
+	}
+	message += formattedConditionResults
+	body, _ := json.Marshal(Body{
+		Topic:    cfg.Topic,
+		Title:    "Gatus: " + ep.DisplayName(),
+		Message:  message,
+		Tags:     []string{tag},
+		Priority: cfg.Priority,
+		Email:    cfg.Email,
+		Click:    cfg.Click,
+	})
+	return body
+}
+
+// GetDefaultAlert returns the provider's default alert configuration
+func (provider *AlertProvider) GetDefaultAlert() *alert.Alert {
+	return provider.DefaultAlert
+}
+
+// GetConfig returns the configuration for the provider with the overrides applied
+func (provider *AlertProvider) GetConfig(group string, alert *alert.Alert) (*Config, error) {
+	cfg := provider.DefaultConfig
+	// Handle group overrides
+	if provider.Overrides != nil {
+		for _, override := range provider.Overrides {
+			if group == override.Group {
+				cfg.Merge(&override.Config)
+				break
+			}
+		}
+	}
+	// Handle alert overrides
+	if len(alert.ProviderOverride) != 0 {
+		overrideConfig := Config{}
+		if err := yaml.Unmarshal(alert.ProviderOverrideAsBytes(), &overrideConfig); err != nil {
+			return nil, err
+		}
+		cfg.Merge(&overrideConfig)
+	}
+	// Validate the configuration
+	err := cfg.Validate()
+	return &cfg, err
+}
+
+// ValidateOverrides validates the alert's provider override and, if present, the group override
+func (provider *AlertProvider) ValidateOverrides(group string, alert *alert.Alert) error {
+	_, err := provider.GetConfig(group, alert)
+	return err
+}

alerting/provider/ntfy/ntfy_test.go

@@ -0,0 +1,414 @@
+package ntfy
+
+import (
+	"encoding/json"
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/TwiN/gatus/v5/alerting/alert"
+	"github.com/TwiN/gatus/v5/config/endpoint"
+)
+
+func TestAlertProvider_Validate(t *testing.T) {
+	scenarios := []struct {
+		name     string
+		provider AlertProvider
+		expected bool
+	}{
+		{
+			name:     "valid",
+			provider: AlertProvider{DefaultConfig: Config{URL: "https://ntfy.sh", Topic: "example", Priority: 1}},
+			expected: true,
+		},
+		{
+			name:     "no-url-should-use-default-value",
+			provider: AlertProvider{DefaultConfig: Config{Topic: "example", Priority: 1}},
+			expected: true,
+		},
+		{
+			name:     "valid-with-token",
+			provider: AlertProvider{DefaultConfig: Config{Topic: "example", Priority: 1, Token: "tk_faketoken"}},
+			expected: true,
+		},
+		{
+			name:     "invalid-token",
+			provider: AlertProvider{DefaultConfig: Config{Topic: "example", Priority: 1, Token: "xx_faketoken"}},
+			expected: false,
+		},
+		{
+			name:     "invalid-topic",
+			provider: AlertProvider{DefaultConfig: Config{URL: "https://ntfy.sh", Topic: "", Priority: 1}},
+			expected: false,
+		},
+		{
+			name:     "invalid-priority-too-high",
+			provider: AlertProvider{DefaultConfig: Config{URL: "https://ntfy.sh", Topic: "example", Priority: 6}},
+			expected: false,
+		},
+		{
+			name:     "invalid-priority-too-low",
+			provider: AlertProvider{DefaultConfig: Config{URL: "https://ntfy.sh", Topic: "example", Priority: -1}},
+			expected: false,
+		},
+		{
+			name:     "no-priority-should-use-default-value",
+			provider: AlertProvider{DefaultConfig: Config{URL: "https://ntfy.sh", Topic: "example"}},
+			expected: true,
+		},
+		{
+			name:     "invalid-override-token",
+			provider: AlertProvider{DefaultConfig: Config{Topic: "example"}, Overrides: []Override{{Group: "g", Config: Config{Token: "xx_faketoken"}}}},
+			expected: false,
+		},
+		{
+			name:     "invalid-override-priority",
+			provider: AlertProvider{DefaultConfig: Config{Topic: "example"}, Overrides: []Override{{Group: "g", Config: Config{Priority: 8}}}},
+			expected: false,
+		},
+		{
+			name:     "no-override-group-name",
+			provider: AlertProvider{DefaultConfig: Config{Topic: "example"}, Overrides: []Override{{}}},
+			expected: false,
+		},
+		{
+			name:     "duplicate-override-group-names",
+			provider: AlertProvider{DefaultConfig: Config{Topic: "example"}, Overrides: []Override{{Group: "g"}, {Group: "g"}}},
+			expected: false,
+		},
+		{
+			name:     "valid-override",
+			provider: AlertProvider{DefaultConfig: Config{Topic: "example"}, Overrides: []Override{{Group: "g1", Config: Config{Priority: 4, Click: "https://example.com"}}, {Group: "g2", Config: Config{Topic: "Example", Token: "tk_faketoken"}}}},
+			expected: true,
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.name, func(t *testing.T) {
+			err := scenario.provider.Validate()
+			if scenario.expected && err != nil {
+				t.Error("expected no error, got", err.Error())
+			}
+			if !scenario.expected && err == nil {
+				t.Error("expected error, got none")
+			}
+		})
+	}
+}
+
+func TestAlertProvider_buildRequestBody(t *testing.T) {
+	firstDescription := "description-1"
+	secondDescription := "description-2"
+	scenarios := []struct {
+		Name         string
+		Provider     AlertProvider
+		Alert        alert.Alert
+		Resolved     bool
+		ExpectedBody string
+	}{
+		{
+			Name:         "triggered",
+			Provider:     AlertProvider{DefaultConfig: Config{URL: "https://ntfy.sh", Topic: "example", Priority: 1}},
+			Alert:        alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     false,
+			ExpectedBody: `{"topic":"example","title":"Gatus: endpoint-name","message":"An alert has been triggered due to having failed 3 time(s) in a row with the following description: description-1\n🔴 [CONNECTED] == true\n🔴 [STATUS] == 200","tags":["rotating_light"],"priority":1}`,
+		},
+		{
+			Name:         "resolved",
+			Provider:     AlertProvider{DefaultConfig: Config{URL: "https://ntfy.sh", Topic: "example", Priority: 2}},
+			Alert:        alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     true,
+			ExpectedBody: `{"topic":"example","title":"Gatus: endpoint-name","message":"An alert has been resolved after passing successfully 5 time(s) in a row with the following description: description-2\n🟢 [CONNECTED] == true\n🟢 [STATUS] == 200","tags":["white_check_mark"],"priority":2}`,
+		},
+		{
+			Name:         "triggered-email",
+			Provider:     AlertProvider{DefaultConfig: Config{URL: "https://ntfy.sh", Topic: "example", Priority: 1, Email: "test@example.com", Click: "example.com"}},
+			Alert:        alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     false,
+			ExpectedBody: `{"topic":"example","title":"Gatus: endpoint-name","message":"An alert has been triggered due to having failed 3 time(s) in a row with the following description: description-1\n🔴 [CONNECTED] == true\n🔴 [STATUS] == 200","tags":["rotating_light"],"priority":1,"email":"test@example.com","click":"example.com"}`,
+		},
+		{
+			Name:         "resolved-email",
+			Provider:     AlertProvider{DefaultConfig: Config{URL: "https://ntfy.sh", Topic: "example", Priority: 2, Email: "test@example.com", Click: "example.com"}},
+			Alert:        alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     true,
+			ExpectedBody: `{"topic":"example","title":"Gatus: endpoint-name","message":"An alert has been resolved after passing successfully 5 time(s) in a row with the following description: description-2\n🟢 [CONNECTED] == true\n🟢 [STATUS] == 200","tags":["white_check_mark"],"priority":2,"email":"test@example.com","click":"example.com"}`,
+		},
+		{
+			Name:         "group-override",
+			Provider:     AlertProvider{DefaultConfig: Config{URL: "https://ntfy.sh", Topic: "example", Priority: 5, Email: "test@example.com", Click: "example.com"}, Overrides: []Override{{Group: "g", Config: Config{Topic: "group-topic", Priority: 4, Email: "override@test.com", Click: "test.com"}}}},
+			Alert:        alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     false,
+			ExpectedBody: `{"topic":"group-topic","title":"Gatus: endpoint-name","message":"An alert has been triggered due to having failed 3 time(s) in a row with the following description: description-1\n🔴 [CONNECTED] == true\n🔴 [STATUS] == 200","tags":["rotating_light"],"priority":4,"email":"override@test.com","click":"test.com"}`,
+		},
+		{
+			Name:         "alert-override",
+			Provider:     AlertProvider{DefaultConfig: Config{URL: "https://ntfy.sh", Topic: "example", Priority: 5, Email: "test@example.com", Click: "example.com"}, Overrides: []Override{{Group: "g", Config: Config{Topic: "group-topic", Priority: 4, Email: "override@test.com", Click: "test.com"}}}},
+			Alert:        alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3, ProviderOverride: map[string]any{"topic": "alert-topic"}},
+			Resolved:     false,
+			ExpectedBody: `{"topic":"alert-topic","title":"Gatus: endpoint-name","message":"An alert has been triggered due to having failed 3 time(s) in a row with the following description: description-1\n🔴 [CONNECTED] == true\n🔴 [STATUS] == 200","tags":["rotating_light"],"priority":4,"email":"override@test.com","click":"test.com"}`,
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			cfg, err := scenario.Provider.GetConfig("g", &scenario.Alert)
+			if err != nil {
+				t.Error("expected no error, got", err.Error())
+			}
+			body := scenario.Provider.buildRequestBody(
+				cfg,
+				&endpoint.Endpoint{Name: "endpoint-name"},
+				&scenario.Alert,
+				&endpoint.Result{
+					ConditionResults: []*endpoint.ConditionResult{
+						{Condition: "[CONNECTED] == true", Success: scenario.Resolved},
+						{Condition: "[STATUS] == 200", Success: scenario.Resolved},
+					},
+				},
+				scenario.Resolved,
+			)
+			if string(body) != scenario.ExpectedBody {
+				t.Errorf("expected:\n%s\ngot:\n%s", scenario.ExpectedBody, body)
+			}
+			out := make(map[string]interface{})
+			if err := json.Unmarshal(body, &out); err != nil {
+				t.Error("expected body to be valid JSON, got error:", err.Error())
+			}
+		})
+	}
+}
+
+func TestAlertProvider_Send(t *testing.T) {
+	description := "description-1"
+	scenarios := []struct {
+		Name            string
+		Provider        AlertProvider
+		Alert           alert.Alert
+		Resolved        bool
+		Group           string
+		ExpectedBody    string
+		ExpectedHeaders map[string]string
+	}{
+		{
+			Name:         "triggered",
+			Provider:     AlertProvider{DefaultConfig: Config{URL: "https://ntfy.sh", Topic: "example", Priority: 1, Email: "test@example.com", Click: "example.com"}},
+			Alert:        alert.Alert{Description: &description, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     false,
+			Group:        "",
+			ExpectedBody: `{"topic":"example","title":"Gatus: endpoint-name","message":"An alert has been triggered due to having failed 3 time(s) in a row with the following description: description-1\n🔴 [CONNECTED] == true\n🔴 [STATUS] == 200","tags":["rotating_light"],"priority":1,"email":"test@example.com","click":"example.com"}`,
+			ExpectedHeaders: map[string]string{
+				"Content-Type": "application/json",
+			},
+		},
+		{
+			Name:         "token",
+			Provider:     AlertProvider{DefaultConfig: Config{URL: "https://ntfy.sh", Topic: "example", Priority: 1, Email: "test@example.com", Click: "example.com", Token: "tk_mytoken"}},
+			Alert:        alert.Alert{Description: &description, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     false,
+			Group:        "",
+			ExpectedBody: `{"topic":"example","title":"Gatus: endpoint-name","message":"An alert has been triggered due to having failed 3 time(s) in a row with the following description: description-1\n🔴 [CONNECTED] == true\n🔴 [STATUS] == 200","tags":["rotating_light"],"priority":1,"email":"test@example.com","click":"example.com"}`,
+			ExpectedHeaders: map[string]string{
+				"Content-Type":  "application/json",
+				"Authorization": "Bearer tk_mytoken",
+			},
+		},
+		{
+			Name:         "no firebase",
+			Provider:     AlertProvider{DefaultConfig: Config{URL: "https://ntfy.sh", Topic: "example", Priority: 1, Email: "test@example.com", Click: "example.com", DisableFirebase: true}},
+			Alert:        alert.Alert{Description: &description, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     false,
+			Group:        "",
+			ExpectedBody: `{"topic":"example","title":"Gatus: endpoint-name","message":"An alert has been triggered due to having failed 3 time(s) in a row with the following description: description-1\n🔴 [CONNECTED] == true\n🔴 [STATUS] == 200","tags":["rotating_light"],"priority":1,"email":"test@example.com","click":"example.com"}`,
+			ExpectedHeaders: map[string]string{
+				"Content-Type": "application/json",
+				"Firebase":     "no",
+			},
+		},
+		{
+			Name:         "no cache",
+			Provider:     AlertProvider{DefaultConfig: Config{URL: "https://ntfy.sh", Topic: "example", Priority: 1, Email: "test@example.com", Click: "example.com", DisableCache: true}},
+			Alert:        alert.Alert{Description: &description, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     false,
+			Group:        "",
+			ExpectedBody: `{"topic":"example","title":"Gatus: endpoint-name","message":"An alert has been triggered due to having failed 3 time(s) in a row with the following description: description-1\n🔴 [CONNECTED] == true\n🔴 [STATUS] == 200","tags":["rotating_light"],"priority":1,"email":"test@example.com","click":"example.com"}`,
+			ExpectedHeaders: map[string]string{
+				"Content-Type": "application/json",
+				"Cache":        "no",
+			},
+		},
+		{
+			Name:         "neither firebase & cache",
+			Provider:     AlertProvider{DefaultConfig: Config{URL: "https://ntfy.sh", Topic: "example", Priority: 1, Email: "test@example.com", Click: "example.com", DisableFirebase: true, DisableCache: true}},
+			Alert:        alert.Alert{Description: &description, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     false,
+			Group:        "",
+			ExpectedBody: `{"topic":"example","title":"Gatus: endpoint-name","message":"An alert has been triggered due to having failed 3 time(s) in a row with the following description: description-1\n🔴 [CONNECTED] == true\n🔴 [STATUS] == 200","tags":["rotating_light"],"priority":1,"email":"test@example.com","click":"example.com"}`,
+			ExpectedHeaders: map[string]string{
+				"Content-Type": "application/json",
+				"Firebase":     "no",
+				"Cache":        "no",
+			},
+		},
+		{
+			Name:         "overrides",
+			Provider:     AlertProvider{DefaultConfig: Config{URL: "https://ntfy.sh", Topic: "example", Priority: 1, Email: "test@example.com", Click: "example.com", Token: "tk_mytoken"}, Overrides: []Override{Override{Group: "other-group", Config: Config{URL: "https://example.com", Token: "tk_othertoken"}}, Override{Group: "test-group", Config: Config{Token: "tk_test_token"}}}},
+			Alert:        alert.Alert{Description: &description, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     false,
+			Group:        "test-group",
+			ExpectedBody: `{"topic":"example","title":"Gatus: test-group/endpoint-name","message":"An alert has been triggered due to having failed 3 time(s) in a row with the following description: description-1\n🔴 [CONNECTED] == true\n🔴 [STATUS] == 200","tags":["rotating_light"],"priority":1,"email":"test@example.com","click":"example.com"}`,
+			ExpectedHeaders: map[string]string{
+				"Content-Type":  "application/json",
+				"Authorization": "Bearer tk_test_token",
+			},
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			// Start a local HTTP server
+			server := httptest.NewServer(http.HandlerFunc(func(rw http.ResponseWriter, req *http.Request) {
+				// Test request parameters
+				for header, value := range scenario.ExpectedHeaders {
+					if value != req.Header.Get(header) {
+						t.Errorf("expected: %s, got: %s", value, req.Header.Get(header))
+					}
+				}
+				body, _ := io.ReadAll(req.Body)
+				if string(body) != scenario.ExpectedBody {
+					t.Errorf("expected:\n%s\ngot:\n%s", scenario.ExpectedBody, body)
+				}
+				// Send response to be tested
+				rw.Write([]byte(`OK`))
+			}))
+			// Close the server when test finishes
+			defer server.Close()
+
+			scenario.Provider.DefaultConfig.URL = server.URL
+			err := scenario.Provider.Send(
+				&endpoint.Endpoint{Name: "endpoint-name", Group: scenario.Group},
+				&scenario.Alert,
+				&endpoint.Result{
+					ConditionResults: []*endpoint.ConditionResult{
+						{Condition: "[CONNECTED] == true", Success: scenario.Resolved},
+						{Condition: "[STATUS] == 200", Success: scenario.Resolved},
+					},
+				},
+				scenario.Resolved,
+			)
+			if err != nil {
+				t.Error("Encountered an error on Send: ", err)
+			}
+		})
+	}
+}
+
+func TestAlertProvider_GetConfig(t *testing.T) {
+	scenarios := []struct {
+		Name           string
+		Provider       AlertProvider
+		InputGroup     string
+		InputAlert     alert.Alert
+		ExpectedOutput Config
+	}{
+		{
+			Name: "provider-no-override-specify-no-group-should-default",
+			Provider: AlertProvider{
+				DefaultConfig: Config{URL: "https://ntfy.sh", Topic: "example", Priority: 1},
+				Overrides:     nil,
+			},
+			InputGroup:     "",
+			InputAlert:     alert.Alert{},
+			ExpectedOutput: Config{URL: "https://ntfy.sh", Topic: "example", Priority: 1},
+		},
+		{
+			Name: "provider-no-override-specify-group-should-default",
+			Provider: AlertProvider{
+				DefaultConfig: Config{URL: "https://ntfy.sh", Topic: "example", Priority: 1},
+				Overrides:     nil,
+			},
+			InputGroup:     "group",
+			InputAlert:     alert.Alert{},
+			ExpectedOutput: Config{URL: "https://ntfy.sh", Topic: "example", Priority: 1},
+		},
+		{
+			Name: "provider-with-override-specify-no-group-should-default",
+			Provider: AlertProvider{
+				DefaultConfig: Config{URL: "https://ntfy.sh", Topic: "example", Priority: 1},
+				Overrides: []Override{
+					{
+						Group:  "group",
+						Config: Config{URL: "https://group-example.com", Topic: "group-topic", Priority: 2},
+					},
+				},
+			},
+			InputGroup:     "",
+			InputAlert:     alert.Alert{},
+			ExpectedOutput: Config{URL: "https://ntfy.sh", Topic: "example", Priority: 1},
+		},
+		{
+			Name: "provider-with-override-specify-group-should-override",
+			Provider: AlertProvider{
+				DefaultConfig: Config{URL: "https://ntfy.sh", Topic: "example", Priority: 1},
+				Overrides: []Override{
+					{
+						Group:  "group",
+						Config: Config{URL: "https://group-example.com", Topic: "group-topic", Priority: 2},
+					},
+				},
+			},
+			InputGroup:     "group",
+			InputAlert:     alert.Alert{},
+			ExpectedOutput: Config{URL: "https://group-example.com", Topic: "group-topic", Priority: 2},
+		},
+		{
+			Name: "provider-with-group-override-and-alert-override--alert-override-should-take-precedence",
+			Provider: AlertProvider{
+				DefaultConfig: Config{URL: "https://ntfy.sh", Topic: "example", Priority: 1},
+				Overrides: []Override{
+					{
+						Group:  "group",
+						Config: Config{URL: "https://group-example.com", Topic: "group-topic", Priority: 2},
+					},
+				},
+			},
+			InputGroup:     "group",
+			InputAlert:     alert.Alert{ProviderOverride: map[string]any{"url": "http://alert-example.com", "topic": "alert-topic", "priority": 3}},
+			ExpectedOutput: Config{URL: "http://alert-example.com", Topic: "alert-topic", Priority: 3},
+		},
+		{
+			Name: "provider-with-partial-overrides",
+			Provider: AlertProvider{
+				DefaultConfig: Config{URL: "https://ntfy.sh", Topic: "example", Priority: 1},
+				Overrides: []Override{
+					{
+						Group:  "group",
+						Config: Config{Topic: "group-topic"},
+					},
+				},
+			},
+			InputGroup:     "group",
+			InputAlert:     alert.Alert{ProviderOverride: map[string]any{"priority": 3}},
+			ExpectedOutput: Config{URL: "https://ntfy.sh", Topic: "group-topic", Priority: 3},
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			got, err := scenario.Provider.GetConfig(scenario.InputGroup, &scenario.InputAlert)
+			if err != nil {
+				t.Fatalf("unexpected error: %s", err)
+			}
+			if got.URL != scenario.ExpectedOutput.URL {
+				t.Errorf("expected url %s, got %s", scenario.ExpectedOutput.URL, got.URL)
+			}
+			if got.Topic != scenario.ExpectedOutput.Topic {
+				t.Errorf("expected topic %s, got %s", scenario.ExpectedOutput.Topic, got.Topic)
+			}
+			if got.Priority != scenario.ExpectedOutput.Priority {
+				t.Errorf("expected priority %d, got %d", scenario.ExpectedOutput.Priority, got.Priority)
+			}
+			// Test ValidateOverrides as well, since it really just calls GetConfig
+			if err = scenario.Provider.ValidateOverrides(scenario.InputGroup, &scenario.InputAlert); err != nil {
+				t.Errorf("unexpected error: %s", err)
+			}
+		})
+	}
+}

alerting/provider/opsgenie/opsgenie.go

@@ -0,0 +1,284 @@
+package opsgenie
+
+import (
+	"bytes"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+	"strconv"
+	"strings"
+
+	"github.com/TwiN/gatus/v5/alerting/alert"
+	"github.com/TwiN/gatus/v5/client"
+	"github.com/TwiN/gatus/v5/config/endpoint"
+	"gopkg.in/yaml.v3"
+)
+
+const (
+	restAPI = "https://api.opsgenie.com/v2/alerts"
+)
+
+var (
+	ErrAPIKeyNotSet = errors.New("api-key not set")
+)
+
+type Config struct {
+	// APIKey to use for
+	APIKey string `yaml:"api-key"`
+
+	// Priority to be used in Opsgenie alert payload
+	//
+	// default: P1
+	Priority string `yaml:"priority"`
+
+	// Source define source to be used in Opsgenie alert payload
+	//
+	// default: gatus
+	Source string `yaml:"source"`
+
+	// EntityPrefix is a prefix to be used in entity argument in Opsgenie alert payload
+	//
+	// default: gatus-
+	EntityPrefix string `yaml:"entity-prefix"`
+
+	//AliasPrefix is a prefix to be used in alias argument in Opsgenie alert payload
+	//
+	// default: gatus-healthcheck-
+	AliasPrefix string `yaml:"alias-prefix"`
+
+	// Tags to be used in Opsgenie alert payload
+	//
+	// default: []
+	Tags []string `yaml:"tags"`
+}
+
+func (cfg *Config) Validate() error {
+	if len(cfg.APIKey) == 0 {
+		return ErrAPIKeyNotSet
+	}
+	if len(cfg.Source) == 0 {
+		cfg.Source = "gatus"
+	}
+	if len(cfg.EntityPrefix) == 0 {
+		cfg.EntityPrefix = "gatus-"
+	}
+	if len(cfg.AliasPrefix) == 0 {
+		cfg.AliasPrefix = "gatus-healthcheck-"
+	}
+	if len(cfg.Priority) == 0 {
+		cfg.Priority = "P1"
+	}
+	return nil
+}
+
+func (cfg *Config) Merge(override *Config) {
+	if len(override.APIKey) > 0 {
+		cfg.APIKey = override.APIKey
+	}
+	if len(override.Priority) > 0 {
+		cfg.Priority = override.Priority
+	}
+	if len(override.Source) > 0 {
+		cfg.Source = override.Source
+	}
+	if len(override.EntityPrefix) > 0 {
+		cfg.EntityPrefix = override.EntityPrefix
+	}
+	if len(override.AliasPrefix) > 0 {
+		cfg.AliasPrefix = override.AliasPrefix
+	}
+	if len(override.Tags) > 0 {
+		cfg.Tags = override.Tags
+	}
+}
+
+type AlertProvider struct {
+	DefaultConfig Config `yaml:",inline"`
+
+	// DefaultAlert is the default alert configuration to use for endpoints with an alert of the appropriate type
+	DefaultAlert *alert.Alert `yaml:"default-alert,omitempty"`
+}
+
+// Validate the provider's configuration
+func (provider *AlertProvider) Validate() error {
+	return provider.DefaultConfig.Validate()
+}
+
+// Send an alert using the provider
+//
+// Relevant: https://docs.opsgenie.com/docs/alert-api
+func (provider *AlertProvider) Send(ep *endpoint.Endpoint, alert *alert.Alert, result *endpoint.Result, resolved bool) error {
+	cfg, err := provider.GetConfig(ep.Group, alert)
+	if err != nil {
+		return err
+	}
+	err = provider.sendAlertRequest(cfg, ep, alert, result, resolved)
+	if err != nil {
+		return err
+	}
+	if resolved {
+		err = provider.closeAlert(cfg, ep, alert)
+		if err != nil {
+			return err
+		}
+	}
+	if alert.IsSendingOnResolved() {
+		if resolved {
+			// The alert has been resolved and there's no error, so we can clear the alert's ResolveKey
+			alert.ResolveKey = ""
+		} else {
+			alert.ResolveKey = cfg.AliasPrefix + buildKey(ep)
+		}
+	}
+	return nil
+}
+
+func (provider *AlertProvider) sendAlertRequest(cfg *Config, ep *endpoint.Endpoint, alert *alert.Alert, result *endpoint.Result, resolved bool) error {
+	payload := provider.buildCreateRequestBody(cfg, ep, alert, result, resolved)
+	return provider.sendRequest(cfg, restAPI, http.MethodPost, payload)
+}
+
+func (provider *AlertProvider) closeAlert(cfg *Config, ep *endpoint.Endpoint, alert *alert.Alert) error {
+	payload := provider.buildCloseRequestBody(ep, alert)
+	url := restAPI + "/" + cfg.AliasPrefix + buildKey(ep) + "/close?identifierType=alias"
+	return provider.sendRequest(cfg, url, http.MethodPost, payload)
+}
+
+func (provider *AlertProvider) sendRequest(cfg *Config, url, method string, payload interface{}) error {
+	body, err := json.Marshal(payload)
+	if err != nil {
+		return fmt.Errorf("error build alert with payload %v: %w", payload, err)
+	}
+	request, err := http.NewRequest(method, url, bytes.NewBuffer(body))
+	if err != nil {
+		return err
+	}
+	request.Header.Set("Content-Type", "application/json")
+	request.Header.Set("Authorization", "GenieKey "+cfg.APIKey)
+	response, err := client.GetHTTPClient(nil).Do(request)
+	if err != nil {
+		return err
+	}
+	defer response.Body.Close()
+	if response.StatusCode > 399 {
+		rBody, _ := io.ReadAll(response.Body)
+		return fmt.Errorf("call to provider alert returned status code %d: %s", response.StatusCode, string(rBody))
+	}
+	return nil
+}
+
+func (provider *AlertProvider) buildCreateRequestBody(cfg *Config, ep *endpoint.Endpoint, alert *alert.Alert, result *endpoint.Result, resolved bool) alertCreateRequest {
+	var message, description string
+	if resolved {
+		message = fmt.Sprintf("RESOLVED: %s - %s", ep.Name, alert.GetDescription())
+		description = fmt.Sprintf("An alert for *%s* has been resolved after passing successfully %d time(s) in a row", ep.DisplayName(), alert.SuccessThreshold)
+	} else {
+		message = fmt.Sprintf("%s - %s", ep.Name, alert.GetDescription())
+		description = fmt.Sprintf("An alert for *%s* has been triggered due to having failed %d time(s) in a row", ep.DisplayName(), alert.FailureThreshold)
+	}
+	if ep.Group != "" {
+		message = fmt.Sprintf("[%s] %s", ep.Group, message)
+	}
+	var formattedConditionResults string
+	for _, conditionResult := range result.ConditionResults {
+		var prefix string
+		if conditionResult.Success {
+			prefix = "▣"
+		} else {
+			prefix = "▢"
+		}
+		formattedConditionResults += fmt.Sprintf("%s - `%s`\n", prefix, conditionResult.Condition)
+	}
+	description = description + "\n" + formattedConditionResults
+	key := buildKey(ep)
+	details := map[string]string{
+		"endpoint:url":    ep.URL,
+		"endpoint:group":  ep.Group,
+		"result:hostname": result.Hostname,
+		"result:ip":       result.IP,
+		"result:dns_code": result.DNSRCode,
+		"result:errors":   strings.Join(result.Errors, ","),
+	}
+	for k, v := range details {
+		if v == "" {
+			delete(details, k)
+		}
+	}
+	if result.HTTPStatus > 0 {
+		details["result:http_status"] = strconv.Itoa(result.HTTPStatus)
+	}
+	return alertCreateRequest{
+		Message:     message,
+		Description: description,
+		Source:      cfg.Source,
+		Priority:    cfg.Priority,
+		Alias:       cfg.AliasPrefix + key,
+		Entity:      cfg.EntityPrefix + key,
+		Tags:        cfg.Tags,
+		Details:     details,
+	}
+}
+
+func (provider *AlertProvider) buildCloseRequestBody(ep *endpoint.Endpoint, alert *alert.Alert) alertCloseRequest {
+	return alertCloseRequest{
+		Source: buildKey(ep),
+		Note:   fmt.Sprintf("RESOLVED: %s - %s", ep.Name, alert.GetDescription()),
+	}
+}
+
+// GetDefaultAlert returns the provider's default alert configuration
+func (provider *AlertProvider) GetDefaultAlert() *alert.Alert {
+	return provider.DefaultAlert
+}
+
+// GetConfig returns the configuration for the provider with the overrides applied
+func (provider *AlertProvider) GetConfig(group string, alert *alert.Alert) (*Config, error) {
+	cfg := provider.DefaultConfig
+	// Handle alert overrides
+	if len(alert.ProviderOverride) != 0 {
+		overrideConfig := Config{}
+		if err := yaml.Unmarshal(alert.ProviderOverrideAsBytes(), &overrideConfig); err != nil {
+			return nil, err
+		}
+		cfg.Merge(&overrideConfig)
+	}
+	// Validate the configuration
+	err := cfg.Validate()
+	return &cfg, err
+}
+
+// ValidateOverrides validates the alert's provider override and, if present, the group override
+func (provider *AlertProvider) ValidateOverrides(group string, alert *alert.Alert) error {
+	_, err := provider.GetConfig(group, alert)
+	return err
+}
+
+func buildKey(ep *endpoint.Endpoint) string {
+	name := toKebabCase(ep.Name)
+	if ep.Group == "" {
+		return name
+	}
+	return toKebabCase(ep.Group) + "-" + name
+}
+
+func toKebabCase(val string) string {
+	return strings.ToLower(strings.ReplaceAll(val, " ", "-"))
+}
+
+type alertCreateRequest struct {
+	Message     string            `json:"message"`
+	Priority    string            `json:"priority"`
+	Source      string            `json:"source"`
+	Entity      string            `json:"entity"`
+	Alias       string            `json:"alias"`
+	Description string            `json:"description"`
+	Tags        []string          `json:"tags,omitempty"`
+	Details     map[string]string `json:"details"`
+}
+
+type alertCloseRequest struct {
+	Source string `json:"source"`
+	Note   string `json:"note"`
+}

alerting/provider/opsgenie/opsgenie_test.go

@@ -0,0 +1,361 @@
+package opsgenie
+
+import (
+	"net/http"
+	"reflect"
+	"testing"
+
+	"github.com/TwiN/gatus/v5/alerting/alert"
+	"github.com/TwiN/gatus/v5/client"
+	"github.com/TwiN/gatus/v5/config/endpoint"
+	"github.com/TwiN/gatus/v5/test"
+)
+
+func TestAlertProvider_Validate(t *testing.T) {
+	invalidProvider := AlertProvider{DefaultConfig: Config{APIKey: ""}}
+	if err := invalidProvider.Validate(); err == nil {
+		t.Error("provider shouldn't have been valid")
+	}
+	validProvider := AlertProvider{DefaultConfig: Config{APIKey: "00000000-0000-0000-0000-000000000000"}}
+	if err := validProvider.Validate(); err != nil {
+		t.Error("provider should've been valid")
+	}
+}
+
+func TestAlertProvider_Send(t *testing.T) {
+	defer client.InjectHTTPClient(nil)
+	description := "my bad alert description"
+	scenarios := []struct {
+		Name             string
+		Provider         AlertProvider
+		Alert            alert.Alert
+		Resolved         bool
+		MockRoundTripper test.MockRoundTripper
+		ExpectedError    bool
+	}{
+		{
+			Name:          "triggered",
+			Provider:      AlertProvider{DefaultConfig: Config{APIKey: "00000000-0000-0000-0000-000000000000"}},
+			Alert:         alert.Alert{Description: &description, SuccessThreshold: 1, FailureThreshold: 1},
+			Resolved:      false,
+			ExpectedError: false,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusOK, Body: http.NoBody}
+			}),
+		},
+		{
+			Name:          "triggered-error",
+			Provider:      AlertProvider{DefaultConfig: Config{APIKey: "00000000-0000-0000-0000-000000000000"}},
+			Alert:         alert.Alert{Description: &description, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:      false,
+			ExpectedError: true,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusInternalServerError, Body: http.NoBody}
+			}),
+		},
+		{
+			Name:          "resolved",
+			Provider:      AlertProvider{DefaultConfig: Config{APIKey: "00000000-0000-0000-0000-000000000000"}},
+			Alert:         alert.Alert{Description: &description, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:      true,
+			ExpectedError: false,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusOK, Body: http.NoBody}
+			}),
+		},
+		{
+			Name:          "resolved-error",
+			Provider:      AlertProvider{DefaultConfig: Config{APIKey: "00000000-0000-0000-0000-000000000000"}},
+			Alert:         alert.Alert{Description: &description, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:      true,
+			ExpectedError: true,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusInternalServerError, Body: http.NoBody}
+			}),
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			client.InjectHTTPClient(&http.Client{Transport: scenario.MockRoundTripper})
+			err := scenario.Provider.Send(
+				&endpoint.Endpoint{Name: "endpoint-name"},
+				&scenario.Alert,
+				&endpoint.Result{
+					ConditionResults: []*endpoint.ConditionResult{
+						{Condition: "[CONNECTED] == true", Success: scenario.Resolved},
+						{Condition: "[STATUS] == 200", Success: scenario.Resolved},
+					},
+				},
+				scenario.Resolved,
+			)
+			if scenario.ExpectedError && err == nil {
+				t.Error("expected error, got none")
+			}
+			if !scenario.ExpectedError && err != nil {
+				t.Error("expected no error, got", err.Error())
+			}
+		})
+	}
+}
+
+func TestAlertProvider_buildCreateRequestBody(t *testing.T) {
+	t.Parallel()
+	description := "alert description"
+	scenarios := []struct {
+		Name     string
+		Provider *AlertProvider
+		Alert    *alert.Alert
+		Endpoint *endpoint.Endpoint
+		Result   *endpoint.Result
+		Resolved bool
+		want     alertCreateRequest
+	}{
+		{
+			Name:     "missing all params (unresolved)",
+			Provider: &AlertProvider{DefaultConfig: Config{APIKey: "00000000-0000-0000-0000-000000000000"}},
+			Alert:    &alert.Alert{},
+			Endpoint: &endpoint.Endpoint{},
+			Result:   &endpoint.Result{},
+			Resolved: false,
+			want: alertCreateRequest{
+				Message:     " - ",
+				Priority:    "P1",
+				Source:      "gatus",
+				Entity:      "gatus-",
+				Alias:       "gatus-healthcheck-",
+				Description: "An alert for ** has been triggered due to having failed 0 time(s) in a row\n",
+				Tags:        nil,
+				Details:     map[string]string{},
+			},
+		},
+		{
+			Name:     "missing all params (resolved)",
+			Provider: &AlertProvider{DefaultConfig: Config{APIKey: "00000000-0000-0000-0000-000000000000"}},
+			Alert:    &alert.Alert{},
+			Endpoint: &endpoint.Endpoint{},
+			Result:   &endpoint.Result{},
+			Resolved: true,
+			want: alertCreateRequest{
+				Message:     "RESOLVED:  - ",
+				Priority:    "P1",
+				Source:      "gatus",
+				Entity:      "gatus-",
+				Alias:       "gatus-healthcheck-",
+				Description: "An alert for ** has been resolved after passing successfully 0 time(s) in a row\n",
+				Tags:        nil,
+				Details:     map[string]string{},
+			},
+		},
+		{
+			Name:     "with default options (unresolved)",
+			Provider: &AlertProvider{DefaultConfig: Config{APIKey: "00000000-0000-0000-0000-000000000000"}},
+			Alert: &alert.Alert{
+				Description:      &description,
+				FailureThreshold: 3,
+			},
+			Endpoint: &endpoint.Endpoint{
+				Name: "my super app",
+			},
+			Result: &endpoint.Result{
+				ConditionResults: []*endpoint.ConditionResult{
+					{
+						Condition: "[STATUS] == 200",
+						Success:   true,
+					},
+					{
+						Condition: "[BODY] == OK",
+						Success:   false,
+					},
+				},
+			},
+			Resolved: false,
+			want: alertCreateRequest{
+				Message:     "my super app - " + description,
+				Priority:    "P1",
+				Source:      "gatus",
+				Entity:      "gatus-my-super-app",
+				Alias:       "gatus-healthcheck-my-super-app",
+				Description: "An alert for *my super app* has been triggered due to having failed 3 time(s) in a row\n▣ - `[STATUS] == 200`\n▢ - `[BODY] == OK`\n",
+				Tags:        nil,
+				Details:     map[string]string{},
+			},
+		},
+		{
+			Name: "with custom options (resolved)",
+			Provider: &AlertProvider{
+				DefaultConfig: Config{
+					Priority:     "P5",
+					EntityPrefix: "oompa-",
+					AliasPrefix:  "loompa-",
+					Source:       "gatus-hc",
+					Tags:         []string{"do-ba-dee-doo"},
+				},
+			},
+			Alert: &alert.Alert{
+				Description:      &description,
+				SuccessThreshold: 4,
+			},
+			Endpoint: &endpoint.Endpoint{
+				Name: "my mega app",
+			},
+			Result: &endpoint.Result{
+				ConditionResults: []*endpoint.ConditionResult{
+					{
+						Condition: "[STATUS] == 200",
+						Success:   true,
+					},
+				},
+			},
+			Resolved: true,
+			want: alertCreateRequest{
+				Message:     "RESOLVED: my mega app - " + description,
+				Priority:    "P5",
+				Source:      "gatus-hc",
+				Entity:      "oompa-my-mega-app",
+				Alias:       "loompa-my-mega-app",
+				Description: "An alert for *my mega app* has been resolved after passing successfully 4 time(s) in a row\n▣ - `[STATUS] == 200`\n",
+				Tags:        []string{"do-ba-dee-doo"},
+				Details:     map[string]string{},
+			},
+		},
+		{
+			Name: "with default options and details (unresolved)",
+			Provider: &AlertProvider{
+				DefaultConfig: Config{Tags: []string{"foo"}, APIKey: "00000000-0000-0000-0000-000000000000"},
+			},
+			Alert: &alert.Alert{
+				Description:      &description,
+				FailureThreshold: 6,
+			},
+			Endpoint: &endpoint.Endpoint{
+				Name:  "my app",
+				Group: "end game",
+				URL:   "https://my.go/app",
+			},
+			Result: &endpoint.Result{
+				HTTPStatus: 400,
+				Hostname:   "my.go",
+				Errors:     []string{"error 01", "error 02"},
+				Success:    false,
+				ConditionResults: []*endpoint.ConditionResult{
+					{
+						Condition: "[STATUS] == 200",
+						Success:   false,
+					},
+				},
+			},
+			Resolved: false,
+			want: alertCreateRequest{
+				Message:     "[end game] my app - " + description,
+				Priority:    "P1",
+				Source:      "gatus",
+				Entity:      "gatus-end-game-my-app",
+				Alias:       "gatus-healthcheck-end-game-my-app",
+				Description: "An alert for *end game/my app* has been triggered due to having failed 6 time(s) in a row\n▢ - `[STATUS] == 200`\n",
+				Tags:        []string{"foo"},
+				Details: map[string]string{
+					"endpoint:url":       "https://my.go/app",
+					"endpoint:group":     "end game",
+					"result:hostname":    "my.go",
+					"result:errors":      "error 01,error 02",
+					"result:http_status": "400",
+				},
+			},
+		},
+	}
+	for _, scenario := range scenarios {
+		actual := scenario
+		t.Run(actual.Name, func(t *testing.T) {
+			_ = scenario.Provider.Validate()
+			if got := actual.Provider.buildCreateRequestBody(&scenario.Provider.DefaultConfig, actual.Endpoint, actual.Alert, actual.Result, actual.Resolved); !reflect.DeepEqual(got, actual.want) {
+				t.Errorf("got:\n%v\nwant:\n%v", got, actual.want)
+			}
+		})
+	}
+}
+
+func TestAlertProvider_buildCloseRequestBody(t *testing.T) {
+	t.Parallel()
+	description := "alert description"
+	scenarios := []struct {
+		Name     string
+		Provider *AlertProvider
+		Alert    *alert.Alert
+		Endpoint *endpoint.Endpoint
+		want     alertCloseRequest
+	}{
+		{
+			Name:     "Missing all values",
+			Provider: &AlertProvider{},
+			Alert:    &alert.Alert{},
+			Endpoint: &endpoint.Endpoint{},
+			want: alertCloseRequest{
+				Source: "",
+				Note:   "RESOLVED:  - ",
+			},
+		},
+		{
+			Name:     "Basic values",
+			Provider: &AlertProvider{},
+			Alert: &alert.Alert{
+				Description: &description,
+			},
+			Endpoint: &endpoint.Endpoint{
+				Name: "endpoint name",
+			},
+			want: alertCloseRequest{
+				Source: "endpoint-name",
+				Note:   "RESOLVED: endpoint name - alert description",
+			},
+		},
+	}
+	for _, scenario := range scenarios {
+		actual := scenario
+		t.Run(actual.Name, func(t *testing.T) {
+			if got := actual.Provider.buildCloseRequestBody(actual.Endpoint, actual.Alert); !reflect.DeepEqual(got, actual.want) {
+				t.Errorf("buildCloseRequestBody() = %v, want %v", got, actual.want)
+			}
+		})
+	}
+}
+
+func TestAlertProvider_GetConfig(t *testing.T) {
+	scenarios := []struct {
+		Name           string
+		Provider       AlertProvider
+		InputAlert     alert.Alert
+		ExpectedOutput Config
+	}{
+		{
+			Name: "provider-no-override-should-default",
+			Provider: AlertProvider{
+				DefaultConfig: Config{APIKey: "00000000-0000-0000-0000-000000000000"},
+			},
+			InputAlert:     alert.Alert{},
+			ExpectedOutput: Config{APIKey: "00000000-0000-0000-0000-000000000000"},
+		},
+		{
+			Name: "provider-with-alert-override--alert-override-should-take-precedence",
+			Provider: AlertProvider{
+				DefaultConfig: Config{APIKey: "00000000-0000-0000-0000-000000000000"},
+			},
+			InputAlert:     alert.Alert{ProviderOverride: map[string]any{"api-key": "00000000-0000-0000-0000-000000000001"}},
+			ExpectedOutput: Config{APIKey: "00000000-0000-0000-0000-000000000001"},
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			got, err := scenario.Provider.GetConfig("", &scenario.InputAlert)
+			if err != nil {
+				t.Fatalf("unexpected error: %s", err)
+			}
+			if got.APIKey != scenario.ExpectedOutput.APIKey {
+				t.Errorf("expected APIKey to be %s, got %s", scenario.ExpectedOutput.APIKey, got.APIKey)
+			}
+			// Test ValidateOverrides as well, since it really just calls GetConfig
+			if err = scenario.Provider.ValidateOverrides("", &scenario.InputAlert); err != nil {
+				t.Errorf("unexpected error: %s", err)
+			}
+		})
+	}
+}

alerting/provider/pagerduty/pagerduty.go

@@ -0,0 +1,195 @@
+package pagerduty
+
+import (
+	"bytes"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+
+	"github.com/TwiN/gatus/v5/alerting/alert"
+	"github.com/TwiN/gatus/v5/client"
+	"github.com/TwiN/gatus/v5/config/endpoint"
+	"github.com/TwiN/logr"
+	"gopkg.in/yaml.v3"
+)
+
+const (
+	restAPIURL = "https://events.pagerduty.com/v2/enqueue"
+)
+
+var (
+	ErrIntegrationKeyNotSet   = errors.New("integration-key must have exactly 32 characters")
+	ErrDuplicateGroupOverride = errors.New("duplicate group override")
+)
+
+type Config struct {
+	IntegrationKey string `yaml:"integration-key"`
+}
+
+func (cfg *Config) Validate() error {
+	if len(cfg.IntegrationKey) != 32 {
+		return ErrIntegrationKeyNotSet
+	}
+	return nil
+}
+
+func (cfg *Config) Merge(override *Config) {
+	if len(override.IntegrationKey) > 0 {
+		cfg.IntegrationKey = override.IntegrationKey
+	}
+}
+
+// AlertProvider is the configuration necessary for sending an alert using PagerDuty
+type AlertProvider struct {
+	DefaultConfig Config `yaml:",inline"`
+
+	// DefaultAlert is the default alert configuration to use for endpoints with an alert of the appropriate type
+	DefaultAlert *alert.Alert `yaml:"default-alert,omitempty"`
+
+	// Overrides is a list of Override that may be prioritized over the default configuration
+	Overrides []Override `yaml:"overrides,omitempty"`
+}
+
+// Override is a case under which the default integration is overridden
+type Override struct {
+	Group  string `yaml:"group"`
+	Config `yaml:",inline"`
+}
+
+// Validate the provider's configuration
+func (provider *AlertProvider) Validate() error {
+	registeredGroups := make(map[string]bool)
+	if provider.Overrides != nil {
+		for _, override := range provider.Overrides {
+			if isAlreadyRegistered := registeredGroups[override.Group]; isAlreadyRegistered || override.Group == "" {
+				return ErrDuplicateGroupOverride
+			}
+			registeredGroups[override.Group] = true
+		}
+	}
+	// Either the default integration key has the right length, or there are overrides who are properly configured.
+	return provider.DefaultConfig.Validate()
+}
+
+// Send an alert using the provider
+//
+// Relevant: https://developer.pagerduty.com/docs/events-api-v2/trigger-events/
+func (provider *AlertProvider) Send(ep *endpoint.Endpoint, alert *alert.Alert, result *endpoint.Result, resolved bool) error {
+	cfg, err := provider.GetConfig(ep.Group, alert)
+	if err != nil {
+		return err
+	}
+	buffer := bytes.NewBuffer(provider.buildRequestBody(cfg, ep, alert, result, resolved))
+	request, err := http.NewRequest(http.MethodPost, restAPIURL, buffer)
+	if err != nil {
+		return err
+	}
+	request.Header.Set("Content-Type", "application/json")
+	response, err := client.GetHTTPClient(nil).Do(request)
+	if err != nil {
+		return err
+	}
+	defer response.Body.Close()
+	if response.StatusCode > 399 {
+		body, _ := io.ReadAll(response.Body)
+		return fmt.Errorf("call to provider alert returned status code %d: %s", response.StatusCode, string(body))
+	}
+	if alert.IsSendingOnResolved() {
+		if resolved {
+			// The alert has been resolved and there's no error, so we can clear the alert's ResolveKey
+			alert.ResolveKey = ""
+		} else {
+			// We need to retrieve the resolve key from the response
+			var payload pagerDutyResponsePayload
+			if err = json.NewDecoder(response.Body).Decode(&payload); err != nil {
+				// Silently fail. We don't want to create tons of alerts just because we failed to parse the body.
+				logr.Errorf("[pagerduty.Send] Ran into error decoding pagerduty response: %s", err.Error())
+			} else {
+				alert.ResolveKey = payload.DedupKey
+			}
+		}
+	}
+	return nil
+}
+
+type Body struct {
+	RoutingKey  string  `json:"routing_key"`
+	DedupKey    string  `json:"dedup_key"`
+	EventAction string  `json:"event_action"`
+	Payload     Payload `json:"payload"`
+}
+
+type Payload struct {
+	Summary  string `json:"summary"`
+	Source   string `json:"source"`
+	Severity string `json:"severity"`
+}
+
+// buildRequestBody builds the request body for the provider
+func (provider *AlertProvider) buildRequestBody(cfg *Config, ep *endpoint.Endpoint, alert *alert.Alert, result *endpoint.Result, resolved bool) []byte {
+	var message, eventAction, resolveKey string
+	if resolved {
+		message = fmt.Sprintf("RESOLVED: %s - %s", ep.DisplayName(), alert.GetDescription())
+		eventAction = "resolve"
+		resolveKey = alert.ResolveKey
+	} else {
+		message = fmt.Sprintf("TRIGGERED: %s - %s", ep.DisplayName(), alert.GetDescription())
+		eventAction = "trigger"
+		resolveKey = ""
+	}
+	body, _ := json.Marshal(Body{
+		RoutingKey:  cfg.IntegrationKey,
+		DedupKey:    resolveKey,
+		EventAction: eventAction,
+		Payload: Payload{
+			Summary:  message,
+			Source:   "Gatus",
+			Severity: "critical",
+		},
+	})
+	return body
+}
+
+// GetDefaultAlert returns the provider's default alert configuration
+func (provider *AlertProvider) GetDefaultAlert() *alert.Alert {
+	return provider.DefaultAlert
+}
+
+// GetConfig returns the configuration for the provider with the overrides applied
+func (provider *AlertProvider) GetConfig(group string, alert *alert.Alert) (*Config, error) {
+	cfg := provider.DefaultConfig
+	// Handle group overrides
+	if provider.Overrides != nil {
+		for _, override := range provider.Overrides {
+			if group == override.Group {
+				cfg.Merge(&override.Config)
+				break
+			}
+		}
+	}
+	// Handle alert overrides
+	if len(alert.ProviderOverride) != 0 {
+		overrideConfig := Config{}
+		if err := yaml.Unmarshal(alert.ProviderOverrideAsBytes(), &overrideConfig); err != nil {
+			return nil, err
+		}
+		cfg.Merge(&overrideConfig)
+	}
+	// Validate the configuration
+	err := cfg.Validate()
+	return &cfg, err
+}
+
+// ValidateOverrides validates the alert's provider override and, if present, the group override
+func (provider *AlertProvider) ValidateOverrides(group string, alert *alert.Alert) error {
+	_, err := provider.GetConfig(group, alert)
+	return err
+}
+
+type pagerDutyResponsePayload struct {
+	Status   string `json:"status"`
+	Message  string `json:"message"`
+	DedupKey string `json:"dedup_key"`
+}

alerting/provider/pagerduty/pagerduty_test.go

@@ -0,0 +1,265 @@
+package pagerduty
+
+import (
+	"encoding/json"
+	"net/http"
+	"testing"
+
+	"github.com/TwiN/gatus/v5/alerting/alert"
+	"github.com/TwiN/gatus/v5/client"
+	"github.com/TwiN/gatus/v5/config/endpoint"
+	"github.com/TwiN/gatus/v5/test"
+)
+
+func TestAlertProvider_Validate(t *testing.T) {
+	invalidProvider := AlertProvider{DefaultConfig: Config{IntegrationKey: ""}}
+	if err := invalidProvider.Validate(); err == nil {
+		t.Error("provider shouldn't have been valid")
+	}
+	validProvider := AlertProvider{DefaultConfig: Config{IntegrationKey: "00000000000000000000000000000000"}}
+	if err := validProvider.Validate(); err != nil {
+		t.Error("provider should've been valid")
+	}
+}
+
+func TestAlertProvider_ValidateWithOverride(t *testing.T) {
+	providerWithInvalidOverrideGroup := AlertProvider{
+		DefaultConfig: Config{IntegrationKey: "00000000000000000000000000000001"},
+		Overrides: []Override{
+			{
+				Config: Config{IntegrationKey: "00000000000000000000000000000002"},
+				Group:  "",
+			},
+		},
+	}
+	if err := providerWithInvalidOverrideGroup.Validate(); err == nil {
+		t.Error("provider Group shouldn't have been valid")
+	}
+	providerWithValidOverride := AlertProvider{
+		DefaultConfig: Config{IntegrationKey: "00000000000000000000000000000001"},
+		Overrides: []Override{
+			{
+				Config: Config{IntegrationKey: "00000000000000000000000000000002"},
+				Group:  "group",
+			},
+		},
+	}
+	if err := providerWithValidOverride.Validate(); err != nil {
+		t.Error("provider should've been valid, got error:", err.Error())
+	}
+}
+
+func TestAlertProvider_Send(t *testing.T) {
+	defer client.InjectHTTPClient(nil)
+	firstDescription := "description-1"
+	secondDescription := "description-2"
+	scenarios := []struct {
+		Name             string
+		Provider         AlertProvider
+		Alert            alert.Alert
+		Resolved         bool
+		MockRoundTripper test.MockRoundTripper
+		ExpectedError    bool
+	}{
+		{
+			Name:     "triggered",
+			Provider: AlertProvider{DefaultConfig: Config{IntegrationKey: "00000000000000000000000000000000"}},
+			Alert:    alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: false,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusOK, Body: http.NoBody}
+			}),
+			ExpectedError: false,
+		},
+		{
+			Name:     "triggered-error",
+			Provider: AlertProvider{DefaultConfig: Config{IntegrationKey: "00000000000000000000000000000000"}},
+			Alert:    alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: false,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusInternalServerError, Body: http.NoBody}
+			}),
+			ExpectedError: true,
+		},
+		{
+			Name:     "resolved",
+			Provider: AlertProvider{DefaultConfig: Config{IntegrationKey: "00000000000000000000000000000000"}},
+			Alert:    alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: true,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusOK, Body: http.NoBody}
+			}),
+			ExpectedError: false,
+		},
+		{
+			Name:     "resolved-error",
+			Provider: AlertProvider{DefaultConfig: Config{IntegrationKey: "00000000000000000000000000000000"}},
+			Alert:    alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: true,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusInternalServerError, Body: http.NoBody}
+			}),
+			ExpectedError: true,
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			client.InjectHTTPClient(&http.Client{Transport: scenario.MockRoundTripper})
+			err := scenario.Provider.Send(
+				&endpoint.Endpoint{Name: "endpoint-name"},
+				&scenario.Alert,
+				&endpoint.Result{
+					ConditionResults: []*endpoint.ConditionResult{
+						{Condition: "[CONNECTED] == true", Success: scenario.Resolved},
+						{Condition: "[STATUS] == 200", Success: scenario.Resolved},
+					},
+				},
+				scenario.Resolved,
+			)
+			if scenario.ExpectedError && err == nil {
+				t.Error("expected error, got none")
+			}
+			if !scenario.ExpectedError && err != nil {
+				t.Error("expected no error, got", err.Error())
+			}
+		})
+	}
+}
+
+func TestAlertProvider_buildRequestBody(t *testing.T) {
+	description := "test"
+	scenarios := []struct {
+		Name         string
+		Provider     AlertProvider
+		Alert        alert.Alert
+		Resolved     bool
+		ExpectedBody string
+	}{
+		{
+			Name:         "triggered",
+			Provider:     AlertProvider{DefaultConfig: Config{IntegrationKey: "00000000000000000000000000000000"}},
+			Alert:        alert.Alert{Description: &description},
+			Resolved:     false,
+			ExpectedBody: "{\"routing_key\":\"00000000000000000000000000000000\",\"dedup_key\":\"\",\"event_action\":\"trigger\",\"payload\":{\"summary\":\"TRIGGERED: endpoint-name - test\",\"source\":\"Gatus\",\"severity\":\"critical\"}}",
+		},
+		{
+			Name:         "resolved",
+			Provider:     AlertProvider{DefaultConfig: Config{IntegrationKey: "00000000000000000000000000000000"}},
+			Alert:        alert.Alert{Description: &description, ResolveKey: "key"},
+			Resolved:     true,
+			ExpectedBody: "{\"routing_key\":\"00000000000000000000000000000000\",\"dedup_key\":\"key\",\"event_action\":\"resolve\",\"payload\":{\"summary\":\"RESOLVED: endpoint-name - test\",\"source\":\"Gatus\",\"severity\":\"critical\"}}",
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			body := scenario.Provider.buildRequestBody(&scenario.Provider.DefaultConfig, &endpoint.Endpoint{Name: "endpoint-name"}, &scenario.Alert, &endpoint.Result{}, scenario.Resolved)
+			if string(body) != scenario.ExpectedBody {
+				t.Errorf("expected:\n%s\ngot:\n%s", scenario.ExpectedBody, body)
+			}
+			out := make(map[string]interface{})
+			if err := json.Unmarshal(body, &out); err != nil {
+				t.Error("expected body to be valid JSON, got error:", err.Error())
+			}
+		})
+	}
+}
+
+func TestAlertProvider_GetDefaultAlert(t *testing.T) {
+	if (&AlertProvider{DefaultAlert: &alert.Alert{}}).GetDefaultAlert() == nil {
+		t.Error("expected default alert to be not nil")
+	}
+	if (&AlertProvider{DefaultAlert: nil}).GetDefaultAlert() != nil {
+		t.Error("expected default alert to be nil")
+	}
+}
+
+func TestAlertProvider_GetConfig(t *testing.T) {
+	scenarios := []struct {
+		Name           string
+		Provider       AlertProvider
+		InputGroup     string
+		InputAlert     alert.Alert
+		ExpectedOutput Config
+	}{
+		{
+			Name: "provider-no-override-specify-no-group-should-default",
+			Provider: AlertProvider{
+				DefaultConfig: Config{IntegrationKey: "00000000000000000000000000000001"},
+				Overrides:     nil,
+			},
+			InputGroup:     "",
+			InputAlert:     alert.Alert{},
+			ExpectedOutput: Config{IntegrationKey: "00000000000000000000000000000001"},
+		},
+		{
+			Name: "provider-no-override-specify-group-should-default",
+			Provider: AlertProvider{
+				DefaultConfig: Config{IntegrationKey: "00000000000000000000000000000001"},
+				Overrides:     nil,
+			},
+			InputGroup:     "group",
+			InputAlert:     alert.Alert{},
+			ExpectedOutput: Config{IntegrationKey: "00000000000000000000000000000001"},
+		},
+		{
+			Name: "provider-with-override-specify-no-group-should-default",
+			Provider: AlertProvider{
+				DefaultConfig: Config{IntegrationKey: "00000000000000000000000000000001"},
+				Overrides: []Override{
+					{
+						Group:  "group",
+						Config: Config{IntegrationKey: "00000000000000000000000000000002"},
+					},
+				},
+			},
+			InputGroup:     "",
+			InputAlert:     alert.Alert{},
+			ExpectedOutput: Config{IntegrationKey: "00000000000000000000000000000001"},
+		},
+		{
+			Name: "provider-with-override-specify-group-should-override",
+			Provider: AlertProvider{
+				DefaultConfig: Config{IntegrationKey: "00000000000000000000000000000001"},
+				Overrides: []Override{
+					{
+						Group:  "group",
+						Config: Config{IntegrationKey: "00000000000000000000000000000002"},
+					},
+				},
+			},
+			InputGroup:     "group",
+			InputAlert:     alert.Alert{},
+			ExpectedOutput: Config{IntegrationKey: "00000000000000000000000000000002"},
+		},
+		{
+			Name: "provider-with-group-override-and-alert-override--alert-override-should-take-precedence",
+			Provider: AlertProvider{
+				DefaultConfig: Config{IntegrationKey: "00000000000000000000000000000001"},
+				Overrides: []Override{
+					{
+						Group:  "group",
+						Config: Config{IntegrationKey: "00000000000000000000000000000002"},
+					},
+				},
+			},
+			InputGroup:     "group",
+			InputAlert:     alert.Alert{ProviderOverride: map[string]any{"integration-key": "00000000000000000000000000000003"}},
+			ExpectedOutput: Config{IntegrationKey: "00000000000000000000000000000003"},
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			got, err := scenario.Provider.GetConfig(scenario.InputGroup, &scenario.InputAlert)
+			if err != nil {
+				t.Fatalf("unexpected error: %s", err)
+			}
+			if got.IntegrationKey != scenario.ExpectedOutput.IntegrationKey {
+				t.Errorf("expected %s, got %s", scenario.ExpectedOutput.IntegrationKey, got.IntegrationKey)
+			}
+			// Test ValidateOverrides as well, since it really just calls GetConfig
+			if err = scenario.Provider.ValidateOverrides(scenario.InputGroup, &scenario.InputAlert); err != nil {
+				t.Errorf("unexpected error: %s", err)
+			}
+		})
+	}
+}

alerting/provider/provider.go

@@ -0,0 +1,123 @@
+package provider
+
+import (
+	"github.com/TwiN/gatus/v5/alerting/alert"
+	"github.com/TwiN/gatus/v5/alerting/provider/awsses"
+	"github.com/TwiN/gatus/v5/alerting/provider/custom"
+	"github.com/TwiN/gatus/v5/alerting/provider/discord"
+	"github.com/TwiN/gatus/v5/alerting/provider/email"
+	"github.com/TwiN/gatus/v5/alerting/provider/gitea"
+	"github.com/TwiN/gatus/v5/alerting/provider/github"
+	"github.com/TwiN/gatus/v5/alerting/provider/gitlab"
+	"github.com/TwiN/gatus/v5/alerting/provider/googlechat"
+	"github.com/TwiN/gatus/v5/alerting/provider/incidentio"
+	"github.com/TwiN/gatus/v5/alerting/provider/jetbrainsspace"
+	"github.com/TwiN/gatus/v5/alerting/provider/matrix"
+	"github.com/TwiN/gatus/v5/alerting/provider/mattermost"
+	"github.com/TwiN/gatus/v5/alerting/provider/messagebird"
+	"github.com/TwiN/gatus/v5/alerting/provider/ntfy"
+	"github.com/TwiN/gatus/v5/alerting/provider/opsgenie"
+	"github.com/TwiN/gatus/v5/alerting/provider/pagerduty"
+	"github.com/TwiN/gatus/v5/alerting/provider/pushover"
+	"github.com/TwiN/gatus/v5/alerting/provider/slack"
+	"github.com/TwiN/gatus/v5/alerting/provider/teams"
+	"github.com/TwiN/gatus/v5/alerting/provider/teamsworkflows"
+	"github.com/TwiN/gatus/v5/alerting/provider/telegram"
+	"github.com/TwiN/gatus/v5/alerting/provider/twilio"
+	"github.com/TwiN/gatus/v5/alerting/provider/zulip"
+	"github.com/TwiN/gatus/v5/config/endpoint"
+)
+
+// AlertProvider is the interface that each provider should implement
+type AlertProvider interface {
+	// Validate the provider's configuration
+	Validate() error
+
+	// Send an alert using the provider
+	Send(ep *endpoint.Endpoint, alert *alert.Alert, result *endpoint.Result, resolved bool) error
+
+	// GetDefaultAlert returns the provider's default alert configuration
+	GetDefaultAlert() *alert.Alert
+
+	// ValidateOverrides validates the alert's provider override and, if present, the group override
+	ValidateOverrides(group string, alert *alert.Alert) error
+}
+
+type Config[T any] interface {
+	Validate() error
+	Merge(override *T)
+}
+
+// MergeProviderDefaultAlertIntoEndpointAlert parses an Endpoint alert by using the provider's default alert as a baseline
+func MergeProviderDefaultAlertIntoEndpointAlert(providerDefaultAlert, endpointAlert *alert.Alert) {
+	if providerDefaultAlert == nil || endpointAlert == nil {
+		return
+	}
+	if endpointAlert.Enabled == nil {
+		endpointAlert.Enabled = providerDefaultAlert.Enabled
+	}
+	if endpointAlert.SendOnResolved == nil {
+		endpointAlert.SendOnResolved = providerDefaultAlert.SendOnResolved
+	}
+	if endpointAlert.Description == nil {
+		endpointAlert.Description = providerDefaultAlert.Description
+	}
+	if endpointAlert.FailureThreshold == 0 {
+		endpointAlert.FailureThreshold = providerDefaultAlert.FailureThreshold
+	}
+	if endpointAlert.SuccessThreshold == 0 {
+		endpointAlert.SuccessThreshold = providerDefaultAlert.SuccessThreshold
+	}
+}
+
+var (
+	// Validate provider interface implementation on compile
+	_ AlertProvider = (*awsses.AlertProvider)(nil)
+	_ AlertProvider = (*custom.AlertProvider)(nil)
+	_ AlertProvider = (*discord.AlertProvider)(nil)
+	_ AlertProvider = (*email.AlertProvider)(nil)
+	_ AlertProvider = (*gitea.AlertProvider)(nil)
+	_ AlertProvider = (*github.AlertProvider)(nil)
+	_ AlertProvider = (*gitlab.AlertProvider)(nil)
+	_ AlertProvider = (*googlechat.AlertProvider)(nil)
+	_ AlertProvider = (*jetbrainsspace.AlertProvider)(nil)
+	_ AlertProvider = (*matrix.AlertProvider)(nil)
+	_ AlertProvider = (*mattermost.AlertProvider)(nil)
+	_ AlertProvider = (*messagebird.AlertProvider)(nil)
+	_ AlertProvider = (*ntfy.AlertProvider)(nil)
+	_ AlertProvider = (*opsgenie.AlertProvider)(nil)
+	_ AlertProvider = (*pagerduty.AlertProvider)(nil)
+	_ AlertProvider = (*pushover.AlertProvider)(nil)
+	_ AlertProvider = (*slack.AlertProvider)(nil)
+	_ AlertProvider = (*teams.AlertProvider)(nil)
+	_ AlertProvider = (*teamsworkflows.AlertProvider)(nil)
+	_ AlertProvider = (*telegram.AlertProvider)(nil)
+	_ AlertProvider = (*twilio.AlertProvider)(nil)
+	_ AlertProvider = (*zulip.AlertProvider)(nil)
+	_ AlertProvider = (*incidentio.AlertProvider)(nil)
+
+	// Validate config interface implementation on compile
+	_ Config[awsses.Config]         = (*awsses.Config)(nil)
+	_ Config[custom.Config]         = (*custom.Config)(nil)
+	_ Config[discord.Config]        = (*discord.Config)(nil)
+	_ Config[email.Config]          = (*email.Config)(nil)
+	_ Config[gitea.Config]          = (*gitea.Config)(nil)
+	_ Config[github.Config]         = (*github.Config)(nil)
+	_ Config[gitlab.Config]         = (*gitlab.Config)(nil)
+	_ Config[googlechat.Config]     = (*googlechat.Config)(nil)
+	_ Config[incidentio.Config]     = (*incidentio.Config)(nil)
+	_ Config[jetbrainsspace.Config] = (*jetbrainsspace.Config)(nil)
+	_ Config[matrix.Config]         = (*matrix.Config)(nil)
+	_ Config[mattermost.Config]     = (*mattermost.Config)(nil)
+	_ Config[messagebird.Config]    = (*messagebird.Config)(nil)
+	_ Config[ntfy.Config]           = (*ntfy.Config)(nil)
+	_ Config[opsgenie.Config]       = (*opsgenie.Config)(nil)
+	_ Config[pagerduty.Config]      = (*pagerduty.Config)(nil)
+	_ Config[pushover.Config]       = (*pushover.Config)(nil)
+	_ Config[slack.Config]          = (*slack.Config)(nil)
+	_ Config[teams.Config]          = (*teams.Config)(nil)
+	_ Config[teamsworkflows.Config] = (*teamsworkflows.Config)(nil)
+	_ Config[telegram.Config]       = (*telegram.Config)(nil)
+	_ Config[twilio.Config]         = (*twilio.Config)(nil)
+	_ Config[zulip.Config]          = (*zulip.Config)(nil)
+)

alerting/provider/provider_test.go

@@ -0,0 +1,153 @@
+package provider
+
+import (
+	"testing"
+
+	"github.com/TwiN/gatus/v5/alerting/alert"
+)
+
+func TestParseWithDefaultAlert(t *testing.T) {
+	type Scenario struct {
+		Name                                             string
+		DefaultAlert, EndpointAlert, ExpectedOutputAlert *alert.Alert
+	}
+	enabled := true
+	disabled := false
+	firstDescription := "description-1"
+	secondDescription := "description-2"
+	scenarios := []Scenario{
+		{
+			Name: "endpoint-alert-type-only",
+			DefaultAlert: &alert.Alert{
+				Enabled:          &enabled,
+				SendOnResolved:   &enabled,
+				Description:      &firstDescription,
+				FailureThreshold: 5,
+				SuccessThreshold: 10,
+			},
+			EndpointAlert: &alert.Alert{
+				Type: alert.TypeDiscord,
+			},
+			ExpectedOutputAlert: &alert.Alert{
+				Type:             alert.TypeDiscord,
+				Enabled:          &enabled,
+				SendOnResolved:   &enabled,
+				Description:      &firstDescription,
+				FailureThreshold: 5,
+				SuccessThreshold: 10,
+			},
+		},
+		{
+			Name: "endpoint-alert-overwrites-default-alert",
+			DefaultAlert: &alert.Alert{
+				Enabled:          &disabled,
+				SendOnResolved:   &disabled,
+				Description:      &firstDescription,
+				FailureThreshold: 5,
+				SuccessThreshold: 10,
+			},
+			EndpointAlert: &alert.Alert{
+				Type:             alert.TypeTelegram,
+				Enabled:          &enabled,
+				SendOnResolved:   &enabled,
+				Description:      &secondDescription,
+				FailureThreshold: 6,
+				SuccessThreshold: 11,
+			},
+			ExpectedOutputAlert: &alert.Alert{
+				Type:             alert.TypeTelegram,
+				Enabled:          &enabled,
+				SendOnResolved:   &enabled,
+				Description:      &secondDescription,
+				FailureThreshold: 6,
+				SuccessThreshold: 11,
+			},
+		},
+		{
+			Name: "endpoint-alert-partially-overwrites-default-alert",
+			DefaultAlert: &alert.Alert{
+				Enabled:          &enabled,
+				SendOnResolved:   &enabled,
+				Description:      &firstDescription,
+				FailureThreshold: 5,
+				SuccessThreshold: 10,
+			},
+			EndpointAlert: &alert.Alert{
+				Type:             alert.TypeDiscord,
+				Enabled:          nil,
+				SendOnResolved:   nil,
+				FailureThreshold: 6,
+				SuccessThreshold: 11,
+			},
+			ExpectedOutputAlert: &alert.Alert{
+				Type:             alert.TypeDiscord,
+				Enabled:          &enabled,
+				SendOnResolved:   &enabled,
+				Description:      &firstDescription,
+				FailureThreshold: 6,
+				SuccessThreshold: 11,
+			},
+		},
+		{
+			Name: "default-alert-type-should-be-ignored",
+			DefaultAlert: &alert.Alert{
+				Type:             alert.TypeTelegram,
+				Enabled:          &enabled,
+				SendOnResolved:   &enabled,
+				Description:      &firstDescription,
+				FailureThreshold: 5,
+				SuccessThreshold: 10,
+			},
+			EndpointAlert: &alert.Alert{
+				Type: alert.TypeDiscord,
+			},
+			ExpectedOutputAlert: &alert.Alert{
+				Type:             alert.TypeDiscord,
+				Enabled:          &enabled,
+				SendOnResolved:   &enabled,
+				Description:      &firstDescription,
+				FailureThreshold: 5,
+				SuccessThreshold: 10,
+			},
+		},
+		{
+			Name: "no-default-alert",
+			DefaultAlert: &alert.Alert{
+				Type:             alert.TypeDiscord,
+				Enabled:          nil,
+				SendOnResolved:   nil,
+				Description:      &firstDescription,
+				FailureThreshold: 2,
+				SuccessThreshold: 5,
+			},
+			EndpointAlert:       nil,
+			ExpectedOutputAlert: nil,
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			MergeProviderDefaultAlertIntoEndpointAlert(scenario.DefaultAlert, scenario.EndpointAlert)
+			if scenario.ExpectedOutputAlert == nil {
+				if scenario.EndpointAlert != nil {
+					t.Fail()
+				}
+				return
+			}
+			if scenario.EndpointAlert.IsEnabled() != scenario.ExpectedOutputAlert.IsEnabled() {
+				t.Errorf("expected EndpointAlert.IsEnabled() to be %v, got %v", scenario.ExpectedOutputAlert.IsEnabled(), scenario.EndpointAlert.IsEnabled())
+			}
+			if scenario.EndpointAlert.IsSendingOnResolved() != scenario.ExpectedOutputAlert.IsSendingOnResolved() {
+				t.Errorf("expected EndpointAlert.IsSendingOnResolved() to be %v, got %v", scenario.ExpectedOutputAlert.IsSendingOnResolved(), scenario.EndpointAlert.IsSendingOnResolved())
+			}
+			if scenario.EndpointAlert.GetDescription() != scenario.ExpectedOutputAlert.GetDescription() {
+				t.Errorf("expected EndpointAlert.GetDescription() to be %v, got %v", scenario.ExpectedOutputAlert.GetDescription(), scenario.EndpointAlert.GetDescription())
+			}
+			if scenario.EndpointAlert.FailureThreshold != scenario.ExpectedOutputAlert.FailureThreshold {
+				t.Errorf("expected EndpointAlert.FailureThreshold to be %v, got %v", scenario.ExpectedOutputAlert.FailureThreshold, scenario.EndpointAlert.FailureThreshold)
+			}
+			if scenario.EndpointAlert.SuccessThreshold != scenario.ExpectedOutputAlert.SuccessThreshold {
+				t.Errorf("expected EndpointAlert.SuccessThreshold to be %v, got %v", scenario.ExpectedOutputAlert.SuccessThreshold, scenario.EndpointAlert.SuccessThreshold)
+			}
+		})
+	}
+}

alerting/provider/pushover/pushover.go

@@ -0,0 +1,205 @@
+package pushover
+
+import (
+	"bytes"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+
+	"github.com/TwiN/gatus/v5/alerting/alert"
+	"github.com/TwiN/gatus/v5/client"
+	"github.com/TwiN/gatus/v5/config/endpoint"
+	"gopkg.in/yaml.v3"
+)
+
+const (
+	restAPIURL      = "https://api.pushover.net/1/messages.json"
+	defaultPriority = 0
+)
+
+var (
+	ErrInvalidApplicationToken = errors.New("application-token must be 30 characters long")
+	ErrInvalidUserKey          = errors.New("user-key must be 30 characters long")
+	ErrInvalidPriority         = errors.New("priority and resolved-priority must be between -2 and 2")
+)
+
+type Config struct {
+	// Key used to authenticate the application sending
+	// See "Your Applications" on the dashboard, or add a new one: https://pushover.net/apps/build
+	ApplicationToken string `yaml:"application-token"`
+
+	// Key of the user or group the messages should be sent to
+	UserKey string `yaml:"user-key"`
+
+	// The title of your message
+	// default: "Gatus: <endpoint>""
+	Title string `yaml:"title,omitempty"`
+
+	// Priority of all messages, ranging from -2 (very low) to 2 (Emergency)
+	// default: 0
+	Priority int `yaml:"priority,omitempty"`
+
+	// Priority of resolved messages, ranging from -2 (very low) to 2 (Emergency)
+	// default: 0
+	ResolvedPriority int `yaml:"resolved-priority,omitempty"`
+
+	// Sound of the messages (see: https://pushover.net/api#sounds)
+	// default: "" (pushover)
+	Sound string `yaml:"sound,omitempty"`
+}
+
+func (cfg *Config) Validate() error {
+	if cfg.Priority == 0 {
+		cfg.Priority = defaultPriority
+	}
+	if cfg.ResolvedPriority == 0 {
+		cfg.ResolvedPriority = defaultPriority
+	}
+	if len(cfg.ApplicationToken) != 30 {
+		return ErrInvalidApplicationToken
+	}
+	if len(cfg.UserKey) != 30 {
+		return ErrInvalidUserKey
+	}
+	if cfg.Priority < -2 || cfg.Priority > 2 || cfg.ResolvedPriority < -2 || cfg.ResolvedPriority > 2 {
+		return ErrInvalidPriority
+	}
+	return nil
+}
+
+func (cfg *Config) Merge(override *Config) {
+	if len(override.ApplicationToken) > 0 {
+		cfg.ApplicationToken = override.ApplicationToken
+	}
+	if len(override.UserKey) > 0 {
+		cfg.UserKey = override.UserKey
+	}
+	if len(override.Title) > 0 {
+		cfg.Title = override.Title
+	}
+	if override.Priority != 0 {
+		cfg.Priority = override.Priority
+	}
+	if override.ResolvedPriority != 0 {
+		cfg.ResolvedPriority = override.ResolvedPriority
+	}
+	if len(override.Sound) > 0 {
+		cfg.Sound = override.Sound
+	}
+}
+
+// AlertProvider is the configuration necessary for sending an alert using Pushover
+type AlertProvider struct {
+	DefaultConfig Config `yaml:",inline"`
+
+	// DefaultAlert is the default alert configuration to use for endpoints with an alert of the appropriate type
+	DefaultAlert *alert.Alert `yaml:"default-alert,omitempty"`
+}
+
+// Validate the provider's configuration
+func (provider *AlertProvider) Validate() error {
+	return provider.DefaultConfig.Validate()
+}
+
+// Send an alert using the provider
+// Reference doc for pushover: https://pushover.net/api
+func (provider *AlertProvider) Send(ep *endpoint.Endpoint, alert *alert.Alert, result *endpoint.Result, resolved bool) error {
+	cfg, err := provider.GetConfig(ep.Group, alert)
+	if err != nil {
+		return err
+	}
+	buffer := bytes.NewBuffer(provider.buildRequestBody(cfg, ep, alert, result, resolved))
+	request, err := http.NewRequest(http.MethodPost, restAPIURL, buffer)
+	if err != nil {
+		return err
+	}
+	request.Header.Set("Content-Type", "application/json")
+	response, err := client.GetHTTPClient(nil).Do(request)
+	if err != nil {
+		return err
+	}
+	defer response.Body.Close()
+	if response.StatusCode > 399 {
+		body, _ := io.ReadAll(response.Body)
+		return fmt.Errorf("call to provider alert returned status code %d: %s", response.StatusCode, string(body))
+	}
+	return err
+}
+
+type Body struct {
+	Token    string `json:"token"`
+	User     string `json:"user"`
+	Title    string `json:"title,omitempty"`
+	Message  string `json:"message"`
+	Priority int    `json:"priority"`
+	Html     int    `json:"html"`
+	Sound    string `json:"sound,omitempty"`
+}
+
+// buildRequestBody builds the request body for the provider
+func (provider *AlertProvider) buildRequestBody(cfg *Config, ep *endpoint.Endpoint, alert *alert.Alert, result *endpoint.Result, resolved bool) []byte {
+	var message, formattedConditionResults string
+	priority := cfg.Priority
+	if resolved {
+		priority = cfg.ResolvedPriority
+		message = fmt.Sprintf("An alert for <b>%s</b> has been resolved after passing successfully %d time(s) in a row", ep.DisplayName(), alert.SuccessThreshold)
+	} else {
+		message = fmt.Sprintf("An alert for <b>%s</b> has been triggered due to having failed %d time(s) in a row", ep.DisplayName(), alert.FailureThreshold)
+	}
+	for _, conditionResult := range result.ConditionResults {
+		var prefix string
+		if conditionResult.Success {
+			prefix = "✅"
+		} else {
+			prefix = "❌"
+		}
+		formattedConditionResults += fmt.Sprintf("\n%s - %s", prefix, conditionResult.Condition)
+	}
+	if len(alert.GetDescription()) > 0 {
+		message += " with the following description: " + alert.GetDescription()
+	}
+	message += formattedConditionResults
+	title := "Gatus: " + ep.DisplayName()
+	if cfg.Title != "" {
+		title = cfg.Title
+	}
+	body, _ := json.Marshal(Body{
+		Token:    cfg.ApplicationToken,
+		User:     cfg.UserKey,
+		Title:    title,
+		Message:  message,
+		Priority: priority,
+		Html:     1,
+		Sound:    cfg.Sound,
+	})
+	return body
+}
+
+// GetDefaultAlert returns the provider's default alert configuration
+func (provider *AlertProvider) GetDefaultAlert() *alert.Alert {
+	return provider.DefaultAlert
+}
+
+// GetConfig returns the configuration for the provider with the overrides applied
+func (provider *AlertProvider) GetConfig(group string, alert *alert.Alert) (*Config, error) {
+	cfg := provider.DefaultConfig
+	// Handle alert overrides
+	if len(alert.ProviderOverride) != 0 {
+		overrideConfig := Config{}
+		if err := yaml.Unmarshal(alert.ProviderOverrideAsBytes(), &overrideConfig); err != nil {
+			return nil, err
+		}
+		cfg.Merge(&overrideConfig)
+	}
+	// Validate the configuration
+	err := cfg.Validate()
+	return &cfg, err
+}
+
+// ValidateOverrides validates the alert's provider override and, if present, the group override
+func (provider *AlertProvider) ValidateOverrides(group string, alert *alert.Alert) error {
+	_, err := provider.GetConfig(group, alert)
+	return err
+}

alerting/provider/pushover/pushover_test.go

@@ -0,0 +1,252 @@
+package pushover
+
+import (
+	"encoding/json"
+	"net/http"
+	"testing"
+
+	"github.com/TwiN/gatus/v5/alerting/alert"
+	"github.com/TwiN/gatus/v5/client"
+	"github.com/TwiN/gatus/v5/config/endpoint"
+	"github.com/TwiN/gatus/v5/test"
+)
+
+func TestPushoverAlertProvider_IsValid(t *testing.T) {
+	t.Run("empty-invalid-provider", func(t *testing.T) {
+		invalidProvider := AlertProvider{}
+		if err := invalidProvider.Validate(); err == nil {
+			t.Error("provider shouldn't have been valid")
+		}
+	})
+	t.Run("valid-provider", func(t *testing.T) {
+		validProvider := AlertProvider{
+			DefaultConfig: Config{
+				ApplicationToken: "aTokenWithLengthOf30characters",
+				UserKey:          "aTokenWithLengthOf30characters",
+				Title:            "Gatus Notification",
+				Priority:         1,
+				ResolvedPriority: 1,
+			},
+		}
+		if err := validProvider.Validate(); err != nil {
+			t.Error("provider should've been valid")
+		}
+	})
+	t.Run("invalid-provider", func(t *testing.T) {
+		invalidProvider := AlertProvider{
+			DefaultConfig: Config{
+				ApplicationToken: "aTokenWithLengthOfMoreThan30characters",
+				UserKey:          "aTokenWithLengthOfMoreThan30characters",
+				Priority:         5,
+			},
+		}
+		if err := invalidProvider.Validate(); err == nil {
+			t.Error("provider should've been invalid")
+		}
+	})
+}
+
+func TestAlertProvider_Send(t *testing.T) {
+	defer client.InjectHTTPClient(nil)
+	firstDescription := "description-1"
+	secondDescription := "description-2"
+	scenarios := []struct {
+		Name             string
+		Provider         AlertProvider
+		Alert            alert.Alert
+		Resolved         bool
+		MockRoundTripper test.MockRoundTripper
+		ExpectedError    bool
+	}{
+		{
+			Name:     "triggered",
+			Provider: AlertProvider{DefaultConfig: Config{ApplicationToken: "aTokenWithLengthOf30characters", UserKey: "aTokenWithLengthOf30characters"}},
+			Alert:    alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: false,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusOK, Body: http.NoBody}
+			}),
+			ExpectedError: false,
+		},
+		{
+			Name:     "triggered-error",
+			Provider: AlertProvider{DefaultConfig: Config{ApplicationToken: "aTokenWithLengthOf30characters", UserKey: "aTokenWithLengthOf30characters"}},
+			Alert:    alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: false,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusInternalServerError, Body: http.NoBody}
+			}),
+			ExpectedError: true,
+		},
+		{
+			Name:     "resolved",
+			Provider: AlertProvider{DefaultConfig: Config{ApplicationToken: "aTokenWithLengthOf30characters", UserKey: "aTokenWithLengthOf30characters"}},
+			Alert:    alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: true,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusOK, Body: http.NoBody}
+			}),
+			ExpectedError: false,
+		},
+		{
+			Name:     "resolved-error",
+			Provider: AlertProvider{DefaultConfig: Config{ApplicationToken: "aTokenWithLengthOf30characters", UserKey: "aTokenWithLengthOf30characters"}},
+			Alert:    alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: true,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusInternalServerError, Body: http.NoBody}
+			}),
+			ExpectedError: true,
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			client.InjectHTTPClient(&http.Client{Transport: scenario.MockRoundTripper})
+			err := scenario.Provider.Send(
+				&endpoint.Endpoint{Name: "endpoint-name"},
+				&scenario.Alert,
+				&endpoint.Result{
+					ConditionResults: []*endpoint.ConditionResult{
+						{Condition: "[CONNECTED] == true", Success: scenario.Resolved},
+						{Condition: "[STATUS] == 200", Success: scenario.Resolved},
+					},
+				},
+				scenario.Resolved,
+			)
+			if scenario.ExpectedError && err == nil {
+				t.Error("expected error, got none")
+			}
+			if !scenario.ExpectedError && err != nil {
+				t.Error("expected no error, got", err.Error())
+			}
+		})
+	}
+}
+
+func TestAlertProvider_buildRequestBody(t *testing.T) {
+	firstDescription := "description-1"
+	secondDescription := "description-2"
+	scenarios := []struct {
+		Name             string
+		Provider         AlertProvider
+		Alert            alert.Alert
+		Resolved         bool
+		ResolvedPriority bool
+		ExpectedBody     string
+	}{
+		{
+			Name:         "triggered",
+			Provider:     AlertProvider{DefaultConfig: Config{ApplicationToken: "TokenWithLengthOf30Characters1", UserKey: "TokenWithLengthOf30Characters4"}},
+			Alert:        alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     false,
+			ExpectedBody: "{\"token\":\"TokenWithLengthOf30Characters1\",\"user\":\"TokenWithLengthOf30Characters4\",\"title\":\"Gatus: endpoint-name\",\"message\":\"An alert for \\u003cb\\u003eendpoint-name\\u003c/b\\u003e has been triggered due to having failed 3 time(s) in a row with the following description: description-1\\n❌ - [CONNECTED] == true\\n❌ - [STATUS] == 200\",\"priority\":0,\"html\":1}",
+		},
+		{
+			Name:         "triggered-customtitle",
+			Provider:     AlertProvider{DefaultConfig: Config{ApplicationToken: "TokenWithLengthOf30Characters1", UserKey: "TokenWithLengthOf30Characters4", Title: "Gatus Notifications"}},
+			Alert:        alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     false,
+			ExpectedBody: "{\"token\":\"TokenWithLengthOf30Characters1\",\"user\":\"TokenWithLengthOf30Characters4\",\"title\":\"Gatus Notifications\",\"message\":\"An alert for \\u003cb\\u003eendpoint-name\\u003c/b\\u003e has been triggered due to having failed 3 time(s) in a row with the following description: description-1\\n❌ - [CONNECTED] == true\\n❌ - [STATUS] == 200\",\"priority\":0,\"html\":1}",
+		},
+		{
+			Name:         "resolved",
+			Provider:     AlertProvider{DefaultConfig: Config{ApplicationToken: "TokenWithLengthOf30Characters2", UserKey: "TokenWithLengthOf30Characters5", Priority: 2, ResolvedPriority: 2}},
+			Alert:        alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     true,
+			ExpectedBody: "{\"token\":\"TokenWithLengthOf30Characters2\",\"user\":\"TokenWithLengthOf30Characters5\",\"title\":\"Gatus: endpoint-name\",\"message\":\"An alert for \\u003cb\\u003eendpoint-name\\u003c/b\\u003e has been resolved after passing successfully 5 time(s) in a row with the following description: description-2\\n✅ - [CONNECTED] == true\\n✅ - [STATUS] == 200\",\"priority\":2,\"html\":1}",
+		},
+		{
+			Name:         "resolved-priority",
+			Provider:     AlertProvider{DefaultConfig: Config{ApplicationToken: "TokenWithLengthOf30Characters2", UserKey: "TokenWithLengthOf30Characters5", Title: "Gatus Notifications", Priority: 2, ResolvedPriority: 0}},
+			Alert:        alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     true,
+			ExpectedBody: "{\"token\":\"TokenWithLengthOf30Characters2\",\"user\":\"TokenWithLengthOf30Characters5\",\"title\":\"Gatus Notifications\",\"message\":\"An alert for \\u003cb\\u003eendpoint-name\\u003c/b\\u003e has been resolved after passing successfully 5 time(s) in a row with the following description: description-2\\n✅ - [CONNECTED] == true\\n✅ - [STATUS] == 200\",\"priority\":0,\"html\":1}",
+		},
+		{
+			Name:         "with-sound",
+			Provider:     AlertProvider{DefaultConfig: Config{ApplicationToken: "TokenWithLengthOf30Characters2", UserKey: "TokenWithLengthOf30Characters5", Title: "Gatus Notifications", Priority: 2, ResolvedPriority: 2, Sound: "falling"}},
+			Alert:        alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     true,
+			ExpectedBody: "{\"token\":\"TokenWithLengthOf30Characters2\",\"user\":\"TokenWithLengthOf30Characters5\",\"title\":\"Gatus Notifications\",\"message\":\"An alert for \\u003cb\\u003eendpoint-name\\u003c/b\\u003e has been resolved after passing successfully 5 time(s) in a row with the following description: description-2\\n✅ - [CONNECTED] == true\\n✅ - [STATUS] == 200\",\"priority\":2,\"html\":1,\"sound\":\"falling\"}",
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			body := scenario.Provider.buildRequestBody(
+				&scenario.Provider.DefaultConfig,
+				&endpoint.Endpoint{Name: "endpoint-name"},
+				&scenario.Alert,
+				&endpoint.Result{
+					ConditionResults: []*endpoint.ConditionResult{
+						{Condition: "[CONNECTED] == true", Success: scenario.Resolved},
+						{Condition: "[STATUS] == 200", Success: scenario.Resolved},
+					},
+				},
+				scenario.Resolved,
+			)
+			if string(body) != scenario.ExpectedBody {
+				t.Errorf("expected:\n%s\ngot:\n%s", scenario.ExpectedBody, body)
+			}
+			out := make(map[string]interface{})
+			if err := json.Unmarshal(body, &out); err != nil {
+				t.Error("expected body to be valid JSON, got error:", err.Error())
+			}
+		})
+	}
+}
+
+func TestAlertProvider_GetDefaultAlert(t *testing.T) {
+	if (&AlertProvider{DefaultAlert: &alert.Alert{}}).GetDefaultAlert() == nil {
+		t.Error("expected default alert to be not nil")
+	}
+	if (&AlertProvider{DefaultAlert: nil}).GetDefaultAlert() != nil {
+		t.Error("expected default alert to be nil")
+	}
+}
+
+func TestAlertProvider_GetConfig(t *testing.T) {
+	scenarios := []struct {
+		Name           string
+		Provider       AlertProvider
+		InputGroup     string
+		InputAlert     alert.Alert
+		ExpectedOutput Config
+	}{
+		{
+			Name: "provider-no-override-specify-no-group-should-default",
+			Provider: AlertProvider{
+				DefaultConfig: Config{ApplicationToken: "aTokenWithLengthOf30characters", UserKey: "aTokenWithLengthOf30characters"},
+			},
+			InputGroup:     "",
+			InputAlert:     alert.Alert{},
+			ExpectedOutput: Config{ApplicationToken: "aTokenWithLengthOf30characters", UserKey: "aTokenWithLengthOf30characters"},
+		},
+		{
+			Name: "provider-with-alert-override",
+			Provider: AlertProvider{
+				DefaultConfig: Config{ApplicationToken: "aTokenWithLengthOf30characters", UserKey: "aTokenWithLengthOf30characters"},
+			},
+			InputGroup:     "group",
+			InputAlert:     alert.Alert{ProviderOverride: map[string]any{"application-token": "TokenWithLengthOf30Characters2", "user-key": "TokenWithLengthOf30Characters3"}},
+			ExpectedOutput: Config{ApplicationToken: "TokenWithLengthOf30Characters2", UserKey: "TokenWithLengthOf30Characters3"},
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			got, err := scenario.Provider.GetConfig(scenario.InputGroup, &scenario.InputAlert)
+			if err != nil {
+				t.Fatalf("unexpected error: %s", err)
+			}
+			if got.ApplicationToken != scenario.ExpectedOutput.ApplicationToken {
+				t.Errorf("expected application token to be %s, got %s", scenario.ExpectedOutput.ApplicationToken, got.ApplicationToken)
+			}
+			if got.UserKey != scenario.ExpectedOutput.UserKey {
+				t.Errorf("expected user key to be %s, got %s", scenario.ExpectedOutput.UserKey, got.UserKey)
+			}
+			// Test ValidateOverrides as well, since it really just calls GetConfig
+			if err = scenario.Provider.ValidateOverrides(scenario.InputGroup, &scenario.InputAlert); err != nil {
+				t.Errorf("unexpected error: %s", err)
+			}
+		})
+	}
+}

alerting/provider/slack/slack.go

@@ -0,0 +1,193 @@
+package slack
+
+import (
+	"bytes"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+
+	"github.com/TwiN/gatus/v5/alerting/alert"
+	"github.com/TwiN/gatus/v5/client"
+	"github.com/TwiN/gatus/v5/config/endpoint"
+	"gopkg.in/yaml.v3"
+)
+
+var (
+	ErrWebhookURLNotSet       = errors.New("webhook-url not set")
+	ErrDuplicateGroupOverride = errors.New("duplicate group override")
+)
+
+type Config struct {
+	WebhookURL string `yaml:"webhook-url"` // Slack webhook URL
+}
+
+func (cfg *Config) Validate() error {
+	if len(cfg.WebhookURL) == 0 {
+		return ErrWebhookURLNotSet
+	}
+	return nil
+}
+
+func (cfg *Config) Merge(override *Config) {
+	if len(override.WebhookURL) > 0 {
+		cfg.WebhookURL = override.WebhookURL
+	}
+}
+
+// AlertProvider is the configuration necessary for sending an alert using Slack
+type AlertProvider struct {
+	DefaultConfig Config `yaml:",inline"`
+
+	// DefaultAlert is the default alert configuration to use for endpoints with an alert of the appropriate type
+	DefaultAlert *alert.Alert `yaml:"default-alert,omitempty"`
+
+	// Overrides is a list of Override that may be prioritized over the default configuration
+	Overrides []Override `yaml:"overrides,omitempty"`
+}
+
+// Override is a case under which the default integration is overridden
+type Override struct {
+	Group  string `yaml:"group"`
+	Config `yaml:",inline"`
+}
+
+// Validate the provider's configuration
+func (provider *AlertProvider) Validate() error {
+	registeredGroups := make(map[string]bool)
+	if provider.Overrides != nil {
+		for _, override := range provider.Overrides {
+			if isAlreadyRegistered := registeredGroups[override.Group]; isAlreadyRegistered || override.Group == "" {
+				return ErrDuplicateGroupOverride
+			}
+			registeredGroups[override.Group] = true
+		}
+	}
+	return provider.DefaultConfig.Validate()
+}
+
+// Send an alert using the provider
+func (provider *AlertProvider) Send(ep *endpoint.Endpoint, alert *alert.Alert, result *endpoint.Result, resolved bool) error {
+	cfg, err := provider.GetConfig(ep.Group, alert)
+	if err != nil {
+		return err
+	}
+	buffer := bytes.NewBuffer(provider.buildRequestBody(ep, alert, result, resolved))
+	request, err := http.NewRequest(http.MethodPost, cfg.WebhookURL, buffer)
+	if err != nil {
+		return err
+	}
+	request.Header.Set("Content-Type", "application/json")
+	response, err := client.GetHTTPClient(nil).Do(request)
+	if err != nil {
+		return err
+	}
+	defer response.Body.Close()
+	if response.StatusCode > 399 {
+		body, _ := io.ReadAll(response.Body)
+		return fmt.Errorf("call to provider alert returned status code %d: %s", response.StatusCode, string(body))
+	}
+	return err
+}
+
+type Body struct {
+	Text        string       `json:"text"`
+	Attachments []Attachment `json:"attachments"`
+}
+
+type Attachment struct {
+	Title  string  `json:"title"`
+	Text   string  `json:"text"`
+	Short  bool    `json:"short"`
+	Color  string  `json:"color"`
+	Fields []Field `json:"fields,omitempty"`
+}
+
+type Field struct {
+	Title string `json:"title"`
+	Value string `json:"value"`
+	Short bool   `json:"short"`
+}
+
+// buildRequestBody builds the request body for the provider
+func (provider *AlertProvider) buildRequestBody(ep *endpoint.Endpoint, alert *alert.Alert, result *endpoint.Result, resolved bool) []byte {
+	var message, color string
+	if resolved {
+		message = fmt.Sprintf("An alert for *%s* has been resolved after passing successfully %d time(s) in a row", ep.DisplayName(), alert.SuccessThreshold)
+		color = "#36A64F"
+	} else {
+		message = fmt.Sprintf("An alert for *%s* has been triggered due to having failed %d time(s) in a row", ep.DisplayName(), alert.FailureThreshold)
+		color = "#DD0000"
+	}
+	var formattedConditionResults string
+	for _, conditionResult := range result.ConditionResults {
+		var prefix string
+		if conditionResult.Success {
+			prefix = ":white_check_mark:"
+		} else {
+			prefix = ":x:"
+		}
+		formattedConditionResults += fmt.Sprintf("%s - `%s`\n", prefix, conditionResult.Condition)
+	}
+	var description string
+	if alertDescription := alert.GetDescription(); len(alertDescription) > 0 {
+		description = ":\n> " + alertDescription
+	}
+	body := Body{
+		Text: "",
+		Attachments: []Attachment{
+			{
+				Title: ":helmet_with_white_cross: Gatus",
+				Text:  message + description,
+				Short: false,
+				Color: color,
+			},
+		},
+	}
+	if len(formattedConditionResults) > 0 {
+		body.Attachments[0].Fields = append(body.Attachments[0].Fields, Field{
+			Title: "Condition results",
+			Value: formattedConditionResults,
+			Short: false,
+		})
+	}
+	bodyAsJSON, _ := json.Marshal(body)
+	return bodyAsJSON
+}
+
+// GetDefaultAlert returns the provider's default alert configuration
+func (provider *AlertProvider) GetDefaultAlert() *alert.Alert {
+	return provider.DefaultAlert
+}
+
+// GetConfig returns the configuration for the provider with the overrides applied
+func (provider *AlertProvider) GetConfig(group string, alert *alert.Alert) (*Config, error) {
+	cfg := provider.DefaultConfig
+	// Handle group overrides
+	if provider.Overrides != nil {
+		for _, override := range provider.Overrides {
+			if group == override.Group {
+				cfg.Merge(&override.Config)
+				break
+			}
+		}
+	}
+	// Handle alert overrides
+	if len(alert.ProviderOverride) != 0 {
+		overrideConfig := Config{}
+		if err := yaml.Unmarshal(alert.ProviderOverrideAsBytes(), &overrideConfig); err != nil {
+			return nil, err
+		}
+		cfg.Merge(&overrideConfig)
+	}
+	// Validate the configuration
+	err := cfg.Validate()
+	return &cfg, err
+}
+
+// ValidateOverrides validates the alert's provider override and, if present, the group override
+func (provider *AlertProvider) ValidateOverrides(group string, alert *alert.Alert) error {
+	_, err := provider.GetConfig(group, alert)
+	return err
+}

alerting/provider/slack/slack_test.go

@@ -0,0 +1,319 @@
+package slack
+
+import (
+	"encoding/json"
+	"net/http"
+	"testing"
+
+	"github.com/TwiN/gatus/v5/alerting/alert"
+	"github.com/TwiN/gatus/v5/client"
+	"github.com/TwiN/gatus/v5/config/endpoint"
+	"github.com/TwiN/gatus/v5/test"
+)
+
+func TestAlertProvider_Validate(t *testing.T) {
+	invalidProvider := AlertProvider{DefaultConfig: Config{WebhookURL: ""}}
+	if err := invalidProvider.Validate(); err == nil {
+		t.Error("provider shouldn't have been valid")
+	}
+	validProvider := AlertProvider{DefaultConfig: Config{WebhookURL: "https://example.com"}}
+	if err := validProvider.Validate(); err != nil {
+		t.Error("provider should've been valid")
+	}
+}
+
+func TestAlertProvider_ValidateWithOverride(t *testing.T) {
+	providerWithInvalidOverrideGroup := AlertProvider{
+		Overrides: []Override{
+			{
+				Config: Config{WebhookURL: "http://example.com"},
+				Group:  "",
+			},
+		},
+	}
+	if err := providerWithInvalidOverrideGroup.Validate(); err == nil {
+		t.Error("provider Group shouldn't have been valid")
+	}
+	providerWithInvalidOverrideTo := AlertProvider{
+		Overrides: []Override{
+			{
+				Config: Config{WebhookURL: ""},
+				Group:  "group",
+			},
+		},
+	}
+	if err := providerWithInvalidOverrideTo.Validate(); err == nil {
+		t.Error("provider integration key shouldn't have been valid")
+	}
+	providerWithValidOverride := AlertProvider{
+		DefaultConfig: Config{WebhookURL: "http://example.com"},
+		Overrides: []Override{
+			{
+				Config: Config{WebhookURL: "http://example.com"},
+				Group:  "group",
+			},
+		},
+	}
+	if err := providerWithValidOverride.Validate(); err != nil {
+		t.Error("provider should've been valid")
+	}
+}
+
+func TestAlertProvider_Send(t *testing.T) {
+	defer client.InjectHTTPClient(nil)
+	firstDescription := "description-1"
+	secondDescription := "description-2"
+	scenarios := []struct {
+		Name             string
+		Provider         AlertProvider
+		Alert            alert.Alert
+		Resolved         bool
+		MockRoundTripper test.MockRoundTripper
+		ExpectedError    bool
+	}{
+		{
+			Name:     "triggered",
+			Provider: AlertProvider{DefaultConfig: Config{WebhookURL: "http://example.com"}},
+			Alert:    alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: false,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusOK, Body: http.NoBody}
+			}),
+			ExpectedError: false,
+		},
+		{
+			Name:     "triggered-error",
+			Provider: AlertProvider{DefaultConfig: Config{WebhookURL: "http://example.com"}},
+			Alert:    alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: false,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusInternalServerError, Body: http.NoBody}
+			}),
+			ExpectedError: true,
+		},
+		{
+			Name:     "resolved",
+			Provider: AlertProvider{DefaultConfig: Config{WebhookURL: "http://example.com"}},
+			Alert:    alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: true,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusOK, Body: http.NoBody}
+			}),
+			ExpectedError: false,
+		},
+		{
+			Name:     "resolved-error",
+			Provider: AlertProvider{DefaultConfig: Config{WebhookURL: "http://example.com"}},
+			Alert:    alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: true,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusInternalServerError, Body: http.NoBody}
+			}),
+			ExpectedError: true,
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			client.InjectHTTPClient(&http.Client{Transport: scenario.MockRoundTripper})
+			err := scenario.Provider.Send(
+				&endpoint.Endpoint{Name: "endpoint-name"},
+				&scenario.Alert,
+				&endpoint.Result{
+					ConditionResults: []*endpoint.ConditionResult{
+						{Condition: "[CONNECTED] == true", Success: scenario.Resolved},
+						{Condition: "[STATUS] == 200", Success: scenario.Resolved},
+					},
+				},
+				scenario.Resolved,
+			)
+			if scenario.ExpectedError && err == nil {
+				t.Error("expected error, got none")
+			}
+			if !scenario.ExpectedError && err != nil {
+				t.Error("expected no error, got", err.Error())
+			}
+		})
+	}
+}
+
+func TestAlertProvider_buildRequestBody(t *testing.T) {
+	firstDescription := "description-1"
+	secondDescription := "description-2"
+	scenarios := []struct {
+		Name         string
+		Provider     AlertProvider
+		Endpoint     endpoint.Endpoint
+		Alert        alert.Alert
+		NoConditions bool
+		Resolved     bool
+		ExpectedBody string
+	}{
+		{
+			Name:         "triggered",
+			Provider:     AlertProvider{},
+			Endpoint:     endpoint.Endpoint{Name: "name"},
+			Alert:        alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     false,
+			ExpectedBody: "{\"text\":\"\",\"attachments\":[{\"title\":\":helmet_with_white_cross: Gatus\",\"text\":\"An alert for *name* has been triggered due to having failed 3 time(s) in a row:\\n\\u003e description-1\",\"short\":false,\"color\":\"#DD0000\",\"fields\":[{\"title\":\"Condition results\",\"value\":\":x: - `[CONNECTED] == true`\\n:x: - `[STATUS] == 200`\\n\",\"short\":false}]}]}",
+		},
+		{
+			Name:         "triggered-with-group",
+			Provider:     AlertProvider{},
+			Endpoint:     endpoint.Endpoint{Name: "name", Group: "group"},
+			Alert:        alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     false,
+			ExpectedBody: "{\"text\":\"\",\"attachments\":[{\"title\":\":helmet_with_white_cross: Gatus\",\"text\":\"An alert for *group/name* has been triggered due to having failed 3 time(s) in a row:\\n\\u003e description-1\",\"short\":false,\"color\":\"#DD0000\",\"fields\":[{\"title\":\"Condition results\",\"value\":\":x: - `[CONNECTED] == true`\\n:x: - `[STATUS] == 200`\\n\",\"short\":false}]}]}",
+		},
+		{
+			Name:         "triggered-with-no-conditions",
+			NoConditions: true,
+			Provider:     AlertProvider{},
+			Endpoint:     endpoint.Endpoint{Name: "name"},
+			Alert:        alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     false,
+			ExpectedBody: "{\"text\":\"\",\"attachments\":[{\"title\":\":helmet_with_white_cross: Gatus\",\"text\":\"An alert for *name* has been triggered due to having failed 3 time(s) in a row:\\n\\u003e description-1\",\"short\":false,\"color\":\"#DD0000\"}]}",
+		},
+		{
+			Name:         "resolved",
+			Provider:     AlertProvider{},
+			Endpoint:     endpoint.Endpoint{Name: "name"},
+			Alert:        alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     true,
+			ExpectedBody: "{\"text\":\"\",\"attachments\":[{\"title\":\":helmet_with_white_cross: Gatus\",\"text\":\"An alert for *name* has been resolved after passing successfully 5 time(s) in a row:\\n\\u003e description-2\",\"short\":false,\"color\":\"#36A64F\",\"fields\":[{\"title\":\"Condition results\",\"value\":\":white_check_mark: - `[CONNECTED] == true`\\n:white_check_mark: - `[STATUS] == 200`\\n\",\"short\":false}]}]}",
+		},
+		{
+			Name:         "resolved-with-group",
+			Provider:     AlertProvider{},
+			Endpoint:     endpoint.Endpoint{Name: "name", Group: "group"},
+			Alert:        alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     true,
+			ExpectedBody: "{\"text\":\"\",\"attachments\":[{\"title\":\":helmet_with_white_cross: Gatus\",\"text\":\"An alert for *group/name* has been resolved after passing successfully 5 time(s) in a row:\\n\\u003e description-2\",\"short\":false,\"color\":\"#36A64F\",\"fields\":[{\"title\":\"Condition results\",\"value\":\":white_check_mark: - `[CONNECTED] == true`\\n:white_check_mark: - `[STATUS] == 200`\\n\",\"short\":false}]}]}",
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			var conditionResults []*endpoint.ConditionResult
+			if !scenario.NoConditions {
+				conditionResults = []*endpoint.ConditionResult{
+					{Condition: "[CONNECTED] == true", Success: scenario.Resolved},
+					{Condition: "[STATUS] == 200", Success: scenario.Resolved},
+				}
+			}
+			body := scenario.Provider.buildRequestBody(
+				&scenario.Endpoint,
+				&scenario.Alert,
+				&endpoint.Result{
+					ConditionResults: conditionResults,
+				},
+				scenario.Resolved,
+			)
+			if string(body) != scenario.ExpectedBody {
+				t.Errorf("expected:\n%s\ngot:\n%s", scenario.ExpectedBody, body)
+			}
+			out := make(map[string]interface{})
+			if err := json.Unmarshal(body, &out); err != nil {
+				t.Error("expected body to be valid JSON, got error:", err.Error())
+			}
+		})
+	}
+}
+
+func TestAlertProvider_GetDefaultAlert(t *testing.T) {
+	if (&AlertProvider{DefaultAlert: &alert.Alert{}}).GetDefaultAlert() == nil {
+		t.Error("expected default alert to be not nil")
+	}
+	if (&AlertProvider{DefaultAlert: nil}).GetDefaultAlert() != nil {
+		t.Error("expected default alert to be nil")
+	}
+}
+
+func TestAlertProvider_GetConfig(t *testing.T) {
+	scenarios := []struct {
+		Name           string
+		Provider       AlertProvider
+		InputGroup     string
+		InputAlert     alert.Alert
+		ExpectedOutput Config
+	}{
+		{
+			Name: "provider-no-override-specify-no-group-should-default",
+			Provider: AlertProvider{
+				DefaultConfig: Config{WebhookURL: "http://example.com"},
+				Overrides:     nil,
+			},
+			InputGroup:     "",
+			InputAlert:     alert.Alert{},
+			ExpectedOutput: Config{WebhookURL: "http://example.com"},
+		},
+		{
+			Name: "provider-no-override-specify-group-should-default",
+			Provider: AlertProvider{
+				DefaultConfig: Config{WebhookURL: "http://example.com"},
+				Overrides:     nil,
+			},
+			InputGroup:     "group",
+			InputAlert:     alert.Alert{},
+			ExpectedOutput: Config{WebhookURL: "http://example.com"},
+		},
+		{
+			Name: "provider-with-override-specify-no-group-should-default",
+			Provider: AlertProvider{
+				DefaultConfig: Config{WebhookURL: "http://example.com"},
+				Overrides: []Override{
+					{
+						Group:  "group",
+						Config: Config{WebhookURL: "http://example01.com"},
+					},
+				},
+			},
+			InputGroup:     "",
+			InputAlert:     alert.Alert{},
+			ExpectedOutput: Config{WebhookURL: "http://example.com"},
+		},
+		{
+			Name: "provider-with-override-specify-group-should-override",
+			Provider: AlertProvider{
+				DefaultConfig: Config{WebhookURL: "http://example.com"},
+				Overrides: []Override{
+					{
+						Group:  "group",
+						Config: Config{WebhookURL: "http://group-example.com"},
+					},
+				},
+			},
+			InputGroup:     "group",
+			InputAlert:     alert.Alert{},
+			ExpectedOutput: Config{WebhookURL: "http://group-example.com"},
+		},
+		{
+			Name: "provider-with-group-override-and-alert-override--alert-override-should-take-precedence",
+			Provider: AlertProvider{
+				DefaultConfig: Config{WebhookURL: "http://example.com"},
+				Overrides: []Override{
+					{
+						Group:  "group",
+						Config: Config{WebhookURL: "http://group-example.com"},
+					},
+				},
+			},
+			InputGroup:     "group",
+			InputAlert:     alert.Alert{ProviderOverride: map[string]any{"webhook-url": "http://alert-example.com"}},
+			ExpectedOutput: Config{WebhookURL: "http://alert-example.com"},
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			got, err := scenario.Provider.GetConfig(scenario.InputGroup, &scenario.InputAlert)
+			if err != nil {
+				t.Fatalf("unexpected error: %s", err)
+			}
+			if got.WebhookURL != scenario.ExpectedOutput.WebhookURL {
+				t.Errorf("expected webhook URL to be %s, got %s", scenario.ExpectedOutput.WebhookURL, got.WebhookURL)
+			}
+			// Test ValidateOverrides as well, since it really just calls GetConfig
+			if err = scenario.Provider.ValidateOverrides(scenario.InputGroup, &scenario.InputAlert); err != nil {
+				t.Errorf("unexpected error: %s", err)
+			}
+		})
+	}
+}

alerting/provider/teams/teams.go

@@ -0,0 +1,196 @@
+package teams
+
+import (
+	"bytes"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+
+	"github.com/TwiN/gatus/v5/alerting/alert"
+	"github.com/TwiN/gatus/v5/client"
+	"github.com/TwiN/gatus/v5/config/endpoint"
+	"gopkg.in/yaml.v3"
+)
+
+var (
+	ErrWebhookURLNotSet       = errors.New("webhook-url not set")
+	ErrDuplicateGroupOverride = errors.New("duplicate group override")
+)
+
+type Config struct {
+	WebhookURL string `yaml:"webhook-url"`
+	Title      string `yaml:"title,omitempty"` // Title of the message that will be sent
+
+	// ClientConfig is the configuration of the client used to communicate with the provider's target
+	ClientConfig *client.Config `yaml:"client,omitempty"`
+}
+
+func (cfg *Config) Validate() error {
+	if len(cfg.WebhookURL) == 0 {
+		return ErrWebhookURLNotSet
+	}
+	return nil
+}
+
+func (cfg *Config) Merge(override *Config) {
+	if override.ClientConfig != nil {
+		cfg.ClientConfig = override.ClientConfig
+	}
+	if len(override.WebhookURL) > 0 {
+		cfg.WebhookURL = override.WebhookURL
+	}
+	if len(override.Title) > 0 {
+		cfg.Title = override.Title
+	}
+}
+
+// AlertProvider is the configuration necessary for sending an alert using Teams
+type AlertProvider struct {
+	DefaultConfig Config `yaml:",inline"`
+
+	// DefaultAlert is the default alert configuration to use for endpoints with an alert of the appropriate type
+	DefaultAlert *alert.Alert `yaml:"default-alert,omitempty"`
+
+	// Overrides is a list of Override that may be prioritized over the default configuration
+	Overrides []Override `yaml:"overrides,omitempty"`
+}
+
+// Override is a case under which the default integration is overridden
+type Override struct {
+	Group  string `yaml:"group"`
+	Config `yaml:",inline"`
+}
+
+// Validate the provider's configuration
+func (provider *AlertProvider) Validate() error {
+	registeredGroups := make(map[string]bool)
+	if provider.Overrides != nil {
+		for _, override := range provider.Overrides {
+			if isAlreadyRegistered := registeredGroups[override.Group]; isAlreadyRegistered || override.Group == "" {
+				return ErrDuplicateGroupOverride
+			}
+			registeredGroups[override.Group] = true
+		}
+	}
+	return provider.DefaultConfig.Validate()
+}
+
+// Send an alert using the provider
+func (provider *AlertProvider) Send(ep *endpoint.Endpoint, alert *alert.Alert, result *endpoint.Result, resolved bool) error {
+	cfg, err := provider.GetConfig(ep.Group, alert)
+	if err != nil {
+		return err
+	}
+	buffer := bytes.NewBuffer(provider.buildRequestBody(cfg, ep, alert, result, resolved))
+	request, err := http.NewRequest(http.MethodPost, cfg.WebhookURL, buffer)
+	if err != nil {
+		return err
+	}
+	request.Header.Set("Content-Type", "application/json")
+	response, err := client.GetHTTPClient(cfg.ClientConfig).Do(request)
+	if err != nil {
+		return err
+	}
+	defer response.Body.Close()
+	if response.StatusCode > 399 {
+		body, _ := io.ReadAll(response.Body)
+		return fmt.Errorf("call to provider alert returned status code %d: %s", response.StatusCode, string(body))
+	}
+	return err
+}
+
+type Body struct {
+	Type       string    `json:"@type"`
+	Context    string    `json:"@context"`
+	ThemeColor string    `json:"themeColor"`
+	Title      string    `json:"title"`
+	Text       string    `json:"text"`
+	Sections   []Section `json:"sections,omitempty"`
+}
+
+type Section struct {
+	ActivityTitle string `json:"activityTitle"`
+	Text          string `json:"text"`
+}
+
+// buildRequestBody builds the request body for the provider
+func (provider *AlertProvider) buildRequestBody(cfg *Config, ep *endpoint.Endpoint, alert *alert.Alert, result *endpoint.Result, resolved bool) []byte {
+	var message, color string
+	if resolved {
+		message = fmt.Sprintf("An alert for *%s* has been resolved after passing successfully %d time(s) in a row", ep.DisplayName(), alert.SuccessThreshold)
+		color = "#36A64F"
+	} else {
+		message = fmt.Sprintf("An alert for *%s* has been triggered due to having failed %d time(s) in a row", ep.DisplayName(), alert.FailureThreshold)
+		color = "#DD0000"
+	}
+	var formattedConditionResults string
+	for _, conditionResult := range result.ConditionResults {
+		var prefix string
+		if conditionResult.Success {
+			prefix = "✅"
+		} else {
+			prefix = "❌"
+		}
+		formattedConditionResults += fmt.Sprintf("%s - `%s`<br/>", prefix, conditionResult.Condition)
+	}
+	var description string
+	if alertDescription := alert.GetDescription(); len(alertDescription) > 0 {
+		description = ": " + alertDescription
+	}
+	body := Body{
+		Type:       "MessageCard",
+		Context:    "http://schema.org/extensions",
+		ThemeColor: color,
+		Title:      cfg.Title,
+		Text:       message + description,
+	}
+	if len(body.Title) == 0 {
+		body.Title = "&#x1F6A8; Gatus"
+	}
+	if len(formattedConditionResults) > 0 {
+		body.Sections = append(body.Sections, Section{
+			ActivityTitle: "Condition results",
+			Text:          formattedConditionResults,
+		})
+	}
+	bodyAsJSON, _ := json.Marshal(body)
+	return bodyAsJSON
+}
+
+// GetDefaultAlert returns the provider's default alert configuration
+func (provider *AlertProvider) GetDefaultAlert() *alert.Alert {
+	return provider.DefaultAlert
+}
+
+// GetConfig returns the configuration for the provider with the overrides applied
+func (provider *AlertProvider) GetConfig(group string, alert *alert.Alert) (*Config, error) {
+	cfg := provider.DefaultConfig
+	// Handle group overrides
+	if provider.Overrides != nil {
+		for _, override := range provider.Overrides {
+			if group == override.Group {
+				cfg.Merge(&override.Config)
+				break
+			}
+		}
+	}
+	// Handle alert overrides
+	if len(alert.ProviderOverride) != 0 {
+		overrideConfig := Config{}
+		if err := yaml.Unmarshal(alert.ProviderOverrideAsBytes(), &overrideConfig); err != nil {
+			return nil, err
+		}
+		cfg.Merge(&overrideConfig)
+	}
+	// Validate the configuration
+	err := cfg.Validate()
+	return &cfg, err
+}
+
+// ValidateOverrides validates the alert's provider override and, if present, the group override
+func (provider *AlertProvider) ValidateOverrides(group string, alert *alert.Alert) error {
+	_, err := provider.GetConfig(group, alert)
+	return err
+}

alerting/provider/teams/teams_test.go

@@ -0,0 +1,298 @@
+package teams
+
+import (
+	"encoding/json"
+	"net/http"
+	"testing"
+
+	"github.com/TwiN/gatus/v5/alerting/alert"
+	"github.com/TwiN/gatus/v5/client"
+	"github.com/TwiN/gatus/v5/config/endpoint"
+	"github.com/TwiN/gatus/v5/test"
+)
+
+func TestAlertProvider_Validate(t *testing.T) {
+	invalidProvider := AlertProvider{DefaultConfig: Config{WebhookURL: ""}}
+	if err := invalidProvider.Validate(); err == nil {
+		t.Error("provider shouldn't have been valid")
+	}
+	validProvider := AlertProvider{DefaultConfig: Config{WebhookURL: "http://example.com"}}
+	if err := validProvider.Validate(); err != nil {
+		t.Error("provider should've been valid")
+	}
+}
+
+func TestAlertProvider_ValidateWithOverride(t *testing.T) {
+	providerWithInvalidOverrideGroup := AlertProvider{
+		Overrides: []Override{
+			{
+				Config: Config{WebhookURL: "http://example.com"},
+				Group:  "",
+			},
+		},
+	}
+	if err := providerWithInvalidOverrideGroup.Validate(); err == nil {
+		t.Error("provider Group shouldn't have been valid")
+	}
+	providerWithInvalidOverrideTo := AlertProvider{
+		Overrides: []Override{
+			{
+				Config: Config{WebhookURL: ""},
+				Group:  "group",
+			},
+		},
+	}
+	if err := providerWithInvalidOverrideTo.Validate(); err == nil {
+		t.Error("provider integration key shouldn't have been valid")
+	}
+	providerWithValidOverride := AlertProvider{
+		DefaultConfig: Config{WebhookURL: "http://example.com"},
+		Overrides: []Override{
+			{
+				Config: Config{WebhookURL: "http://example.com"},
+				Group:  "group",
+			},
+		},
+	}
+	if err := providerWithValidOverride.Validate(); err != nil {
+		t.Error("provider should've been valid")
+	}
+}
+
+func TestAlertProvider_Send(t *testing.T) {
+	defer client.InjectHTTPClient(nil)
+	firstDescription := "description-1"
+	secondDescription := "description-2"
+	scenarios := []struct {
+		Name             string
+		Provider         AlertProvider
+		Alert            alert.Alert
+		Resolved         bool
+		MockRoundTripper test.MockRoundTripper
+		ExpectedError    bool
+	}{
+		{
+			Name:     "triggered",
+			Provider: AlertProvider{DefaultConfig: Config{WebhookURL: "http://example.com"}},
+			Alert:    alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: false,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusOK, Body: http.NoBody}
+			}),
+			ExpectedError: false,
+		},
+		{
+			Name:     "triggered-error",
+			Provider: AlertProvider{DefaultConfig: Config{WebhookURL: "http://example.com"}},
+			Alert:    alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: false,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusInternalServerError, Body: http.NoBody}
+			}),
+			ExpectedError: true,
+		},
+		{
+			Name:     "resolved",
+			Provider: AlertProvider{DefaultConfig: Config{WebhookURL: "http://example.com"}},
+			Alert:    alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: true,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusOK, Body: http.NoBody}
+			}),
+			ExpectedError: false,
+		},
+		{
+			Name:     "resolved-error",
+			Provider: AlertProvider{DefaultConfig: Config{WebhookURL: "http://example.com"}},
+			Alert:    alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: true,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusInternalServerError, Body: http.NoBody}
+			}),
+			ExpectedError: true,
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			client.InjectHTTPClient(&http.Client{Transport: scenario.MockRoundTripper})
+			err := scenario.Provider.Send(
+				&endpoint.Endpoint{Name: "endpoint-name"},
+				&scenario.Alert,
+				&endpoint.Result{
+					ConditionResults: []*endpoint.ConditionResult{
+						{Condition: "[CONNECTED] == true", Success: scenario.Resolved},
+						{Condition: "[STATUS] == 200", Success: scenario.Resolved},
+					},
+				},
+				scenario.Resolved,
+			)
+			if scenario.ExpectedError && err == nil {
+				t.Error("expected error, got none")
+			}
+			if !scenario.ExpectedError && err != nil {
+				t.Error("expected no error, got", err.Error())
+			}
+		})
+	}
+}
+
+func TestAlertProvider_buildRequestBody(t *testing.T) {
+	firstDescription := "description-1"
+	secondDescription := "description-2"
+	scenarios := []struct {
+		Name         string
+		Provider     AlertProvider
+		Alert        alert.Alert
+		NoConditions bool
+		Resolved     bool
+		ExpectedBody string
+	}{
+		{
+			Name:         "triggered",
+			Provider:     AlertProvider{},
+			Alert:        alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     false,
+			ExpectedBody: "{\"@type\":\"MessageCard\",\"@context\":\"http://schema.org/extensions\",\"themeColor\":\"#DD0000\",\"title\":\"\\u0026#x1F6A8; Gatus\",\"text\":\"An alert for *endpoint-name* has been triggered due to having failed 3 time(s) in a row: description-1\",\"sections\":[{\"activityTitle\":\"Condition results\",\"text\":\"\\u0026#x274C; - `[CONNECTED] == true`\\u003cbr/\\u003e\\u0026#x274C; - `[STATUS] == 200`\\u003cbr/\\u003e\"}]}",
+		},
+		{
+			Name:         "resolved",
+			Provider:     AlertProvider{},
+			Alert:        alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     true,
+			ExpectedBody: "{\"@type\":\"MessageCard\",\"@context\":\"http://schema.org/extensions\",\"themeColor\":\"#36A64F\",\"title\":\"\\u0026#x1F6A8; Gatus\",\"text\":\"An alert for *endpoint-name* has been resolved after passing successfully 5 time(s) in a row: description-2\",\"sections\":[{\"activityTitle\":\"Condition results\",\"text\":\"\\u0026#x2705; - `[CONNECTED] == true`\\u003cbr/\\u003e\\u0026#x2705; - `[STATUS] == 200`\\u003cbr/\\u003e\"}]}",
+		},
+		{
+			Name:         "resolved-with-no-conditions",
+			NoConditions: true,
+			Provider:     AlertProvider{},
+			Alert:        alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     true,
+			ExpectedBody: "{\"@type\":\"MessageCard\",\"@context\":\"http://schema.org/extensions\",\"themeColor\":\"#36A64F\",\"title\":\"\\u0026#x1F6A8; Gatus\",\"text\":\"An alert for *endpoint-name* has been resolved after passing successfully 5 time(s) in a row: description-2\"}",
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			var conditionResults []*endpoint.ConditionResult
+			if !scenario.NoConditions {
+				conditionResults = []*endpoint.ConditionResult{
+					{Condition: "[CONNECTED] == true", Success: scenario.Resolved},
+					{Condition: "[STATUS] == 200", Success: scenario.Resolved},
+				}
+			}
+			body := scenario.Provider.buildRequestBody(
+				&scenario.Provider.DefaultConfig,
+				&endpoint.Endpoint{Name: "endpoint-name"},
+				&scenario.Alert,
+				&endpoint.Result{ConditionResults: conditionResults},
+				scenario.Resolved,
+			)
+			if string(body) != scenario.ExpectedBody {
+				t.Errorf("expected:\n%s\ngot:\n%s", scenario.ExpectedBody, body)
+			}
+			out := make(map[string]interface{})
+			if err := json.Unmarshal(body, &out); err != nil {
+				t.Error("expected body to be valid JSON, got error:", err.Error())
+			}
+		})
+	}
+}
+
+func TestAlertProvider_GetDefaultAlert(t *testing.T) {
+	if (&AlertProvider{DefaultAlert: &alert.Alert{}}).GetDefaultAlert() == nil {
+		t.Error("expected default alert to be not nil")
+	}
+	if (&AlertProvider{DefaultAlert: nil}).GetDefaultAlert() != nil {
+		t.Error("expected default alert to be nil")
+	}
+}
+
+func TestAlertProvider_GetConfig(t *testing.T) {
+	scenarios := []struct {
+		Name           string
+		Provider       AlertProvider
+		InputGroup     string
+		InputAlert     alert.Alert
+		ExpectedOutput Config
+	}{
+		{
+			Name: "provider-no-override-specify-no-group-should-default",
+			Provider: AlertProvider{
+				DefaultConfig: Config{WebhookURL: "http://example.com"},
+				Overrides:     nil,
+			},
+			InputGroup:     "",
+			InputAlert:     alert.Alert{},
+			ExpectedOutput: Config{WebhookURL: "http://example.com"},
+		},
+		{
+			Name: "provider-no-override-specify-group-should-default",
+			Provider: AlertProvider{
+				DefaultConfig: Config{WebhookURL: "http://example.com"},
+				Overrides:     nil,
+			},
+			InputGroup:     "group",
+			InputAlert:     alert.Alert{},
+			ExpectedOutput: Config{WebhookURL: "http://example.com"},
+		},
+		{
+			Name: "provider-with-override-specify-no-group-should-default",
+			Provider: AlertProvider{
+				DefaultConfig: Config{WebhookURL: "http://example.com"},
+				Overrides: []Override{
+					{
+						Group:  "group",
+						Config: Config{WebhookURL: "http://example01.com"},
+					},
+				},
+			},
+			InputGroup:     "",
+			InputAlert:     alert.Alert{},
+			ExpectedOutput: Config{WebhookURL: "http://example.com"},
+		},
+		{
+			Name: "provider-with-override-specify-group-should-override",
+			Provider: AlertProvider{
+				DefaultConfig: Config{WebhookURL: "http://example.com"},
+				Overrides: []Override{
+					{
+						Group:  "group",
+						Config: Config{WebhookURL: "http://group-example.com"},
+					},
+				},
+			},
+			InputGroup:     "group",
+			InputAlert:     alert.Alert{},
+			ExpectedOutput: Config{WebhookURL: "http://group-example.com"},
+		},
+		{
+			Name: "provider-with-group-override-and-alert-override--alert-override-should-take-precedence",
+			Provider: AlertProvider{
+				DefaultConfig: Config{WebhookURL: "http://example.com"},
+				Overrides: []Override{
+					{
+						Group:  "group",
+						Config: Config{WebhookURL: "http://group-example.com"},
+					},
+				},
+			},
+			InputGroup:     "group",
+			InputAlert:     alert.Alert{ProviderOverride: map[string]any{"webhook-url": "http://alert-example.com"}},
+			ExpectedOutput: Config{WebhookURL: "http://alert-example.com"},
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			got, err := scenario.Provider.GetConfig(scenario.InputGroup, &scenario.InputAlert)
+			if err != nil {
+				t.Fatalf("unexpected error: %s", err)
+			}
+			if got.WebhookURL != scenario.ExpectedOutput.WebhookURL {
+				t.Errorf("expected webhook URL to be %s, got %s", scenario.ExpectedOutput.WebhookURL, got.WebhookURL)
+			}
+			// Test ValidateOverrides as well, since it really just calls GetConfig
+			if err = scenario.Provider.ValidateOverrides(scenario.InputGroup, &scenario.InputAlert); err != nil {
+				t.Errorf("unexpected error: %s", err)
+			}
+		})
+	}
+}

alerting/provider/teamsworkflows/teamsworkflows.go

@@ -0,0 +1,255 @@
+package teamsworkflows
+
+import (
+	"bytes"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+
+	"github.com/TwiN/gatus/v5/alerting/alert"
+	"github.com/TwiN/gatus/v5/client"
+	"github.com/TwiN/gatus/v5/config/endpoint"
+	"gopkg.in/yaml.v3"
+)
+
+var (
+	ErrWebhookURLNotSet       = errors.New("webhook-url not set")
+	ErrDuplicateGroupOverride = errors.New("duplicate group override")
+)
+
+type Config struct {
+	WebhookURL string `yaml:"webhook-url"`
+	Title      string `yaml:"title,omitempty"` // Title of the message that will be sent
+}
+
+func (cfg *Config) Validate() error {
+	if len(cfg.WebhookURL) == 0 {
+		return ErrWebhookURLNotSet
+	}
+	return nil
+}
+
+func (cfg *Config) Merge(override *Config) {
+	if len(override.WebhookURL) > 0 {
+		cfg.WebhookURL = override.WebhookURL
+	}
+	if len(override.Title) > 0 {
+		cfg.Title = override.Title
+	}
+}
+
+// AlertProvider is the configuration necessary for sending an alert using Teams
+type AlertProvider struct {
+	DefaultConfig Config `yaml:",inline"`
+
+	// DefaultAlert is the default alert configuration to use for endpoints with an alert of the appropriate type
+	DefaultAlert *alert.Alert `yaml:"default-alert,omitempty"`
+
+	// Overrides is a list of Override that may be prioritized over the default configuration
+	Overrides []Override `yaml:"overrides,omitempty"`
+}
+
+// Override is a case under which the default integration is overridden
+type Override struct {
+	Group  string `yaml:"group"`
+	Config `yaml:",inline"`
+}
+
+// Validate the provider's configuration
+func (provider *AlertProvider) Validate() error {
+	registeredGroups := make(map[string]bool)
+	if provider.Overrides != nil {
+		for _, override := range provider.Overrides {
+			if isAlreadyRegistered := registeredGroups[override.Group]; isAlreadyRegistered || override.Group == "" {
+				return ErrDuplicateGroupOverride
+			}
+			registeredGroups[override.Group] = true
+		}
+	}
+	return provider.DefaultConfig.Validate()
+}
+
+// Send an alert using the provider
+func (provider *AlertProvider) Send(ep *endpoint.Endpoint, alert *alert.Alert, result *endpoint.Result, resolved bool) error {
+	cfg, err := provider.GetConfig(ep.Group, alert)
+	if err != nil {
+		return err
+	}
+	buffer := bytes.NewBuffer(provider.buildRequestBody(cfg, ep, alert, result, resolved))
+	request, err := http.NewRequest(http.MethodPost, cfg.WebhookURL, buffer)
+	if err != nil {
+		return err
+	}
+	request.Header.Set("Content-Type", "application/json")
+	response, err := client.GetHTTPClient(nil).Do(request)
+	if err != nil {
+		return err
+	}
+	defer response.Body.Close()
+	if response.StatusCode > 399 {
+		body, _ := io.ReadAll(response.Body)
+		return fmt.Errorf("call to provider alert returned status code %d: %s", response.StatusCode, string(body))
+	}
+	return err
+}
+
+// AdaptiveCardBody represents the structure of an Adaptive Card
+type AdaptiveCardBody struct {
+	Type    string      `json:"type"`
+	Version string      `json:"version"`
+	Body    []CardBody  `json:"body"`
+	MSTeams MSTeamsBody `json:"msteams"`
+}
+
+// CardBody represents the body of the Adaptive Card
+type CardBody struct {
+	Type      string       `json:"type"`
+	Text      string       `json:"text,omitempty"`
+	Wrap      bool         `json:"wrap"`
+	Separator bool         `json:"separator,omitempty"`
+	Size      string       `json:"size,omitempty"`
+	Weight    string       `json:"weight,omitempty"`
+	Items     []CardBody   `json:"items,omitempty"`
+	Facts     []Fact       `json:"facts,omitempty"`
+	FactSet   *FactSetBody `json:"factSet,omitempty"`
+	Style     string       `json:"style,omitempty"`
+}
+
+// MSTeamsBody represents the msteams options
+type MSTeamsBody struct {
+	Width string `json:"width"`
+}
+
+// FactSetBody represents the FactSet in the Adaptive Card
+type FactSetBody struct {
+	Type  string `json:"type"`
+	Facts []Fact `json:"facts"`
+}
+
+// Fact represents an individual fact in the FactSet
+type Fact struct {
+	Title string `json:"title"`
+	Value string `json:"value"`
+}
+
+// buildRequestBody builds the request body for the provider
+func (provider *AlertProvider) buildRequestBody(cfg *Config, ep *endpoint.Endpoint, alert *alert.Alert, result *endpoint.Result, resolved bool) []byte {
+	var message string
+	var themeColor string
+	if resolved {
+		message = fmt.Sprintf("An alert for **%s** has been resolved after passing successfully %d time(s) in a row.", ep.DisplayName(), alert.SuccessThreshold)
+		themeColor = "Good" // green
+	} else {
+		message = fmt.Sprintf("An alert for **%s** has been triggered due to having failed %d time(s) in a row.", ep.DisplayName(), alert.FailureThreshold)
+		themeColor = "Attention" // red
+	}
+
+	// Configure default title if it's not provided
+	title := "⛑️ Gatus"
+	if cfg.Title != "" {
+		title = cfg.Title
+	}
+
+	// Build the facts from the condition results
+	var facts []Fact
+	for _, conditionResult := range result.ConditionResults {
+		var key string
+		if conditionResult.Success {
+			key = "✅"
+		} else {
+			key = "❌"
+		}
+		facts = append(facts, Fact{
+			Title: key,
+			Value: conditionResult.Condition,
+		})
+	}
+
+	cardContent := AdaptiveCardBody{
+		Type:    "AdaptiveCard",
+		Version: "1.4", // Version 1.5 and 1.6 doesn't seem to be supported by Teams as of 27/08/2024
+		Body: []CardBody{
+			{
+				Type:  "Container",
+				Style: themeColor,
+				Items: []CardBody{
+					{
+						Type:  "Container",
+						Style: "Default",
+						Items: []CardBody{
+							{
+								Type:   "TextBlock",
+								Text:   title,
+								Size:   "Medium",
+								Weight: "Bolder",
+							},
+							{
+								Type: "TextBlock",
+								Text: message,
+								Wrap: true,
+							},
+							{
+								Type:  "FactSet",
+								Facts: facts,
+							},
+						},
+					},
+				},
+			},
+		},
+		MSTeams: MSTeamsBody{
+			Width: "Full",
+		},
+	}
+
+	attachment := map[string]interface{}{
+		"contentType": "application/vnd.microsoft.card.adaptive",
+		"content":     cardContent,
+	}
+
+	payload := map[string]interface{}{
+		"type":        "message",
+		"attachments": []interface{}{attachment},
+	}
+
+	bodyAsJSON, _ := json.Marshal(payload)
+	return bodyAsJSON
+}
+
+// GetDefaultAlert returns the provider's default alert configuration
+func (provider *AlertProvider) GetDefaultAlert() *alert.Alert {
+	return provider.DefaultAlert
+}
+
+// GetConfig returns the configuration for the provider with the overrides applied
+func (provider *AlertProvider) GetConfig(group string, alert *alert.Alert) (*Config, error) {
+	cfg := provider.DefaultConfig
+	// Handle group overrides
+	if provider.Overrides != nil {
+		for _, override := range provider.Overrides {
+			if group == override.Group {
+				cfg.Merge(&override.Config)
+				break
+			}
+		}
+	}
+	// Handle alert overrides
+	if len(alert.ProviderOverride) != 0 {
+		overrideConfig := Config{}
+		if err := yaml.Unmarshal(alert.ProviderOverrideAsBytes(), &overrideConfig); err != nil {
+			return nil, err
+		}
+		cfg.Merge(&overrideConfig)
+	}
+	// Validate the configuration
+	err := cfg.Validate()
+	return &cfg, err
+}
+
+// ValidateOverrides validates the alert's provider override and, if present, the group override
+func (provider *AlertProvider) ValidateOverrides(group string, alert *alert.Alert) error {
+	_, err := provider.GetConfig(group, alert)
+	return err
+}

alerting/provider/teamsworkflows/teamsworkflows_test.go

@@ -0,0 +1,298 @@
+package teamsworkflows
+
+import (
+	"encoding/json"
+	"net/http"
+	"testing"
+
+	"github.com/TwiN/gatus/v5/alerting/alert"
+	"github.com/TwiN/gatus/v5/client"
+	"github.com/TwiN/gatus/v5/config/endpoint"
+	"github.com/TwiN/gatus/v5/test"
+)
+
+func TestAlertProvider_Validate(t *testing.T) {
+	invalidProvider := AlertProvider{DefaultConfig: Config{WebhookURL: ""}}
+	if err := invalidProvider.Validate(); err == nil {
+		t.Error("provider shouldn't have been valid")
+	}
+	validProvider := AlertProvider{DefaultConfig: Config{WebhookURL: "http://example.com"}}
+	if err := validProvider.Validate(); err != nil {
+		t.Error("provider should've been valid, got", err.Error())
+	}
+}
+
+func TestAlertProvider_ValidateWithOverride(t *testing.T) {
+	providerWithInvalidOverrideGroup := AlertProvider{
+		Overrides: []Override{
+			{
+				Config: Config{WebhookURL: "http://example.com"},
+				Group:  "",
+			},
+		},
+	}
+	if err := providerWithInvalidOverrideGroup.Validate(); err == nil {
+		t.Error("provider Group shouldn't have been valid")
+	}
+	providerWithInvalidOverrideTo := AlertProvider{
+		Overrides: []Override{
+			{
+				Config: Config{WebhookURL: ""},
+				Group:  "group",
+			},
+		},
+	}
+	if err := providerWithInvalidOverrideTo.Validate(); err == nil {
+		t.Error("provider integration key shouldn't have been valid")
+	}
+	providerWithValidOverride := AlertProvider{
+		DefaultConfig: Config{WebhookURL: "http://example.com"},
+		Overrides: []Override{
+			{
+				Config: Config{WebhookURL: "http://example.com"},
+				Group:  "group",
+			},
+		},
+	}
+	if err := providerWithValidOverride.Validate(); err != nil {
+		t.Error("provider should've been valid")
+	}
+}
+
+func TestAlertProvider_Send(t *testing.T) {
+	defer client.InjectHTTPClient(nil)
+	firstDescription := "description-1"
+	secondDescription := "description-2"
+	scenarios := []struct {
+		Name             string
+		Provider         AlertProvider
+		Alert            alert.Alert
+		Resolved         bool
+		MockRoundTripper test.MockRoundTripper
+		ExpectedError    bool
+	}{
+		{
+			Name:     "triggered",
+			Provider: AlertProvider{DefaultConfig: Config{WebhookURL: "http://example.com"}},
+			Alert:    alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: false,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusOK, Body: http.NoBody}
+			}),
+			ExpectedError: false,
+		},
+		{
+			Name:     "triggered-error",
+			Provider: AlertProvider{DefaultConfig: Config{WebhookURL: "http://example.com"}},
+			Alert:    alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: false,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusInternalServerError, Body: http.NoBody}
+			}),
+			ExpectedError: true,
+		},
+		{
+			Name:     "resolved",
+			Provider: AlertProvider{DefaultConfig: Config{WebhookURL: "http://example.com"}},
+			Alert:    alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: true,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusOK, Body: http.NoBody}
+			}),
+			ExpectedError: false,
+		},
+		{
+			Name:     "resolved-error",
+			Provider: AlertProvider{DefaultConfig: Config{WebhookURL: "http://example.com"}},
+			Alert:    alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: true,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusInternalServerError, Body: http.NoBody}
+			}),
+			ExpectedError: true,
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			client.InjectHTTPClient(&http.Client{Transport: scenario.MockRoundTripper})
+			err := scenario.Provider.Send(
+				&endpoint.Endpoint{Name: "endpoint-name"},
+				&scenario.Alert,
+				&endpoint.Result{
+					ConditionResults: []*endpoint.ConditionResult{
+						{Condition: "[CONNECTED] == true", Success: scenario.Resolved},
+						{Condition: "[STATUS] == 200", Success: scenario.Resolved},
+					},
+				},
+				scenario.Resolved,
+			)
+			if scenario.ExpectedError && err == nil {
+				t.Error("expected error, got none")
+			}
+			if !scenario.ExpectedError && err != nil {
+				t.Error("expected no error, got", err.Error())
+			}
+		})
+	}
+}
+
+func TestAlertProvider_buildRequestBody(t *testing.T) {
+	firstDescription := "description-1"
+	secondDescription := "description-2"
+	scenarios := []struct {
+		Name         string
+		Provider     AlertProvider
+		Alert        alert.Alert
+		NoConditions bool
+		Resolved     bool
+		ExpectedBody string
+	}{
+		{
+			Name:         "triggered",
+			Provider:     AlertProvider{},
+			Alert:        alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     false,
+			ExpectedBody: "{\"attachments\":[{\"content\":{\"type\":\"AdaptiveCard\",\"version\":\"1.4\",\"body\":[{\"type\":\"Container\",\"wrap\":false,\"items\":[{\"type\":\"Container\",\"wrap\":false,\"items\":[{\"type\":\"TextBlock\",\"text\":\"⛑️ Gatus\",\"wrap\":false,\"size\":\"Medium\",\"weight\":\"Bolder\"},{\"type\":\"TextBlock\",\"text\":\"An alert for **endpoint-name** has been triggered due to having failed 3 time(s) in a row.\",\"wrap\":true},{\"type\":\"FactSet\",\"wrap\":false,\"facts\":[{\"title\":\"❌\",\"value\":\"[CONNECTED] == true\"},{\"title\":\"❌\",\"value\":\"[STATUS] == 200\"}]}],\"style\":\"Default\"}],\"style\":\"Attention\"}],\"msteams\":{\"width\":\"Full\"}},\"contentType\":\"application/vnd.microsoft.card.adaptive\"}],\"type\":\"message\"}",
+		},
+		{
+			Name:         "resolved",
+			Provider:     AlertProvider{},
+			Alert:        alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     true,
+			ExpectedBody: "{\"attachments\":[{\"content\":{\"type\":\"AdaptiveCard\",\"version\":\"1.4\",\"body\":[{\"type\":\"Container\",\"wrap\":false,\"items\":[{\"type\":\"Container\",\"wrap\":false,\"items\":[{\"type\":\"TextBlock\",\"text\":\"⛑️ Gatus\",\"wrap\":false,\"size\":\"Medium\",\"weight\":\"Bolder\"},{\"type\":\"TextBlock\",\"text\":\"An alert for **endpoint-name** has been resolved after passing successfully 5 time(s) in a row.\",\"wrap\":true},{\"type\":\"FactSet\",\"wrap\":false,\"facts\":[{\"title\":\"✅\",\"value\":\"[CONNECTED] == true\"},{\"title\":\"✅\",\"value\":\"[STATUS] == 200\"}]}],\"style\":\"Default\"}],\"style\":\"Good\"}],\"msteams\":{\"width\":\"Full\"}},\"contentType\":\"application/vnd.microsoft.card.adaptive\"}],\"type\":\"message\"}",
+		},
+		{
+			Name:         "resolved-with-no-conditions",
+			NoConditions: true,
+			Provider:     AlertProvider{},
+			Alert:        alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     true,
+			ExpectedBody: "{\"attachments\":[{\"content\":{\"type\":\"AdaptiveCard\",\"version\":\"1.4\",\"body\":[{\"type\":\"Container\",\"wrap\":false,\"items\":[{\"type\":\"Container\",\"wrap\":false,\"items\":[{\"type\":\"TextBlock\",\"text\":\"⛑️ Gatus\",\"wrap\":false,\"size\":\"Medium\",\"weight\":\"Bolder\"},{\"type\":\"TextBlock\",\"text\":\"An alert for **endpoint-name** has been resolved after passing successfully 5 time(s) in a row.\",\"wrap\":true},{\"type\":\"FactSet\",\"wrap\":false}],\"style\":\"Default\"}],\"style\":\"Good\"}],\"msteams\":{\"width\":\"Full\"}},\"contentType\":\"application/vnd.microsoft.card.adaptive\"}],\"type\":\"message\"}",
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			var conditionResults []*endpoint.ConditionResult
+			if !scenario.NoConditions {
+				conditionResults = []*endpoint.ConditionResult{
+					{Condition: "[CONNECTED] == true", Success: scenario.Resolved},
+					{Condition: "[STATUS] == 200", Success: scenario.Resolved},
+				}
+			}
+			body := scenario.Provider.buildRequestBody(
+				&scenario.Provider.DefaultConfig,
+				&endpoint.Endpoint{Name: "endpoint-name"},
+				&scenario.Alert,
+				&endpoint.Result{ConditionResults: conditionResults},
+				scenario.Resolved,
+			)
+			if string(body) != scenario.ExpectedBody {
+				t.Errorf("expected:\n%s\ngot:\n%s", scenario.ExpectedBody, body)
+			}
+			out := make(map[string]interface{})
+			if err := json.Unmarshal(body, &out); err != nil {
+				t.Error("expected body to be valid JSON, got error:", err.Error())
+			}
+		})
+	}
+}
+
+func TestAlertProvider_GetDefaultAlert(t *testing.T) {
+	if (&AlertProvider{DefaultAlert: &alert.Alert{}}).GetDefaultAlert() == nil {
+		t.Error("expected default alert to be not nil")
+	}
+	if (&AlertProvider{DefaultAlert: nil}).GetDefaultAlert() != nil {
+		t.Error("expected default alert to be nil")
+	}
+}
+
+func TestAlertProvider_GetConfig(t *testing.T) {
+	scenarios := []struct {
+		Name           string
+		Provider       AlertProvider
+		InputGroup     string
+		InputAlert     alert.Alert
+		ExpectedOutput Config
+	}{
+		{
+			Name: "provider-no-override-specify-no-group-should-default",
+			Provider: AlertProvider{
+				DefaultConfig: Config{WebhookURL: "http://example.com"},
+				Overrides:     nil,
+			},
+			InputGroup:     "",
+			InputAlert:     alert.Alert{},
+			ExpectedOutput: Config{WebhookURL: "http://example.com"},
+		},
+		{
+			Name: "provider-no-override-specify-group-should-default",
+			Provider: AlertProvider{
+				DefaultConfig: Config{WebhookURL: "http://example.com"},
+				Overrides:     nil,
+			},
+			InputGroup:     "group",
+			InputAlert:     alert.Alert{},
+			ExpectedOutput: Config{WebhookURL: "http://example.com"},
+		},
+		{
+			Name: "provider-with-override-specify-no-group-should-default",
+			Provider: AlertProvider{
+				DefaultConfig: Config{WebhookURL: "http://example.com"},
+				Overrides: []Override{
+					{
+						Group:  "group",
+						Config: Config{WebhookURL: "http://example01.com"},
+					},
+				},
+			},
+			InputGroup:     "",
+			InputAlert:     alert.Alert{},
+			ExpectedOutput: Config{WebhookURL: "http://example.com"},
+		},
+		{
+			Name: "provider-with-override-specify-group-should-override",
+			Provider: AlertProvider{
+				DefaultConfig: Config{WebhookURL: "http://example.com"},
+				Overrides: []Override{
+					{
+						Group:  "group",
+						Config: Config{WebhookURL: "http://group-example.com"},
+					},
+				},
+			},
+			InputGroup:     "group",
+			InputAlert:     alert.Alert{},
+			ExpectedOutput: Config{WebhookURL: "http://group-example.com"},
+		},
+		{
+			Name: "provider-with-group-override-and-alert-override--alert-override-should-take-precedence",
+			Provider: AlertProvider{
+				DefaultConfig: Config{WebhookURL: "http://example.com"},
+				Overrides: []Override{
+					{
+						Group:  "group",
+						Config: Config{WebhookURL: "http://group-example.com"},
+					},
+				},
+			},
+			InputGroup:     "group",
+			InputAlert:     alert.Alert{ProviderOverride: map[string]any{"webhook-url": "http://alert-example.com"}},
+			ExpectedOutput: Config{WebhookURL: "http://alert-example.com"},
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			got, err := scenario.Provider.GetConfig(scenario.InputGroup, &scenario.InputAlert)
+			if err != nil {
+				t.Fatalf("unexpected error: %s", err)
+			}
+			if got.WebhookURL != scenario.ExpectedOutput.WebhookURL {
+				t.Errorf("expected webhook URL to be %s, got %s", scenario.ExpectedOutput.WebhookURL, got.WebhookURL)
+			}
+			// Test ValidateOverrides as well, since it really just calls GetConfig
+			if err = scenario.Provider.ValidateOverrides(scenario.InputGroup, &scenario.InputAlert); err != nil {
+				t.Errorf("unexpected error: %s", err)
+			}
+		})
+	}
+}

alerting/provider/telegram/telegram.go

@@ -0,0 +1,191 @@
+package telegram
+
+import (
+	"bytes"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+
+	"github.com/TwiN/gatus/v5/alerting/alert"
+	"github.com/TwiN/gatus/v5/client"
+	"github.com/TwiN/gatus/v5/config/endpoint"
+	"gopkg.in/yaml.v3"
+)
+
+const defaultApiUrl = "https://api.telegram.org"
+
+var (
+	ErrTokenNotSet            = errors.New("token not set")
+	ErrIDNotSet               = errors.New("id not set")
+	ErrDuplicateGroupOverride = errors.New("duplicate group override")
+)
+
+type Config struct {
+	Token  string `yaml:"token"`
+	ID     string `yaml:"id"`
+	ApiUrl string `yaml:"api-url"`
+
+	ClientConfig *client.Config `yaml:"client,omitempty"`
+}
+
+func (cfg *Config) Validate() error {
+	if len(cfg.ApiUrl) == 0 {
+		cfg.ApiUrl = defaultApiUrl
+	}
+	if len(cfg.Token) == 0 {
+		return ErrTokenNotSet
+	}
+	if len(cfg.ID) == 0 {
+		return ErrIDNotSet
+	}
+	return nil
+}
+
+func (cfg *Config) Merge(override *Config) {
+	if override.ClientConfig != nil {
+		cfg.ClientConfig = override.ClientConfig
+	}
+	if len(override.Token) > 0 {
+		cfg.Token = override.Token
+	}
+	if len(override.ID) > 0 {
+		cfg.ID = override.ID
+	}
+	if len(override.ApiUrl) > 0 {
+		cfg.ApiUrl = override.ApiUrl
+	}
+}
+
+// AlertProvider is the configuration necessary for sending an alert using Telegram
+type AlertProvider struct {
+	DefaultConfig Config `yaml:",inline"`
+
+	// DefaultAlert is the default alert configuration to use for endpoints with an alert of the appropriate type
+	DefaultAlert *alert.Alert `yaml:"default-alert,omitempty"`
+
+	// Overrides is a list of overrides that may be prioritized over the default configuration
+	Overrides []*Override `yaml:"overrides,omitempty"`
+}
+
+// Override is a configuration that may be prioritized over the default configuration
+type Override struct {
+	Group  string `yaml:"group"`
+	Config `yaml:",inline"`
+}
+
+// Validate the provider's configuration
+func (provider *AlertProvider) Validate() error {
+	registeredGroups := make(map[string]bool)
+	if provider.Overrides != nil {
+		for _, override := range provider.Overrides {
+			if isAlreadyRegistered := registeredGroups[override.Group]; isAlreadyRegistered || override.Group == "" {
+				return ErrDuplicateGroupOverride
+			}
+			registeredGroups[override.Group] = true
+		}
+	}
+	return provider.DefaultConfig.Validate()
+}
+
+// Send an alert using the provider
+func (provider *AlertProvider) Send(ep *endpoint.Endpoint, alert *alert.Alert, result *endpoint.Result, resolved bool) error {
+	cfg, err := provider.GetConfig(ep.Group, alert)
+	if err != nil {
+		return err
+	}
+	buffer := bytes.NewBuffer(provider.buildRequestBody(cfg, ep, alert, result, resolved))
+	request, err := http.NewRequest(http.MethodPost, fmt.Sprintf("%s/bot%s/sendMessage", cfg.ApiUrl, cfg.Token), buffer)
+	if err != nil {
+		return err
+	}
+	request.Header.Set("Content-Type", "application/json")
+	response, err := client.GetHTTPClient(cfg.ClientConfig).Do(request)
+	if err != nil {
+		return err
+	}
+	defer response.Body.Close()
+	if response.StatusCode > 399 {
+		body, _ := io.ReadAll(response.Body)
+		return fmt.Errorf("call to provider alert returned status code %d: %s", response.StatusCode, string(body))
+	}
+	return err
+}
+
+type Body struct {
+	ChatID    string `json:"chat_id"`
+	Text      string `json:"text"`
+	ParseMode string `json:"parse_mode"`
+}
+
+// buildRequestBody builds the request body for the provider
+func (provider *AlertProvider) buildRequestBody(cfg *Config, ep *endpoint.Endpoint, alert *alert.Alert, result *endpoint.Result, resolved bool) []byte {
+	var message string
+	if resolved {
+		message = fmt.Sprintf("An alert for *%s* has been resolved:\n—\n    _healthcheck passing successfully %d time(s) in a row_\n—  ", ep.DisplayName(), alert.SuccessThreshold)
+	} else {
+		message = fmt.Sprintf("An alert for *%s* has been triggered:\n—\n    _healthcheck failed %d time(s) in a row_\n—  ", ep.DisplayName(), alert.FailureThreshold)
+	}
+	var formattedConditionResults string
+	if len(result.ConditionResults) > 0 {
+		formattedConditionResults = "\n*Condition results*\n"
+		for _, conditionResult := range result.ConditionResults {
+			var prefix string
+			if conditionResult.Success {
+				prefix = "✅"
+			} else {
+				prefix = "❌"
+			}
+			formattedConditionResults += fmt.Sprintf("%s - `%s`\n", prefix, conditionResult.Condition)
+		}
+	}
+	var text string
+	if len(alert.GetDescription()) > 0 {
+		text = fmt.Sprintf("⛑ *Gatus* \n%s \n*Description* \n_%s_  \n%s", message, alert.GetDescription(), formattedConditionResults)
+	} else {
+		text = fmt.Sprintf("⛑ *Gatus* \n%s%s", message, formattedConditionResults)
+	}
+	bodyAsJSON, _ := json.Marshal(Body{
+		ChatID:    cfg.ID,
+		Text:      text,
+		ParseMode: "MARKDOWN",
+	})
+	return bodyAsJSON
+}
+
+// GetDefaultAlert returns the provider's default alert configuration
+func (provider *AlertProvider) GetDefaultAlert() *alert.Alert {
+	return provider.DefaultAlert
+}
+
+// GetConfig returns the configuration for the provider with the overrides applied
+func (provider *AlertProvider) GetConfig(group string, alert *alert.Alert) (*Config, error) {
+	cfg := provider.DefaultConfig
+	// Handle group overrides
+	if provider.Overrides != nil {
+		for _, override := range provider.Overrides {
+			if group == override.Group {
+				cfg.Merge(&override.Config)
+				break
+			}
+		}
+	}
+	// Handle alert overrides
+	if len(alert.ProviderOverride) != 0 {
+		overrideConfig := Config{}
+		if err := yaml.Unmarshal(alert.ProviderOverrideAsBytes(), &overrideConfig); err != nil {
+			return nil, err
+		}
+		cfg.Merge(&overrideConfig)
+	}
+	// Validate the configuration
+	err := cfg.Validate()
+	return &cfg, err
+}
+
+// ValidateOverrides validates the alert's provider override and, if present, the group override
+func (provider *AlertProvider) ValidateOverrides(group string, alert *alert.Alert) error {
+	_, err := provider.GetConfig(group, alert)
+	return err
+}

alerting/provider/telegram/telegram_test.go

@@ -0,0 +1,252 @@
+package telegram
+
+import (
+	"encoding/json"
+	"net/http"
+	"testing"
+
+	"github.com/TwiN/gatus/v5/alerting/alert"
+	"github.com/TwiN/gatus/v5/client"
+	"github.com/TwiN/gatus/v5/config/endpoint"
+	"github.com/TwiN/gatus/v5/test"
+)
+
+func TestAlertProvider_Validate(t *testing.T) {
+	t.Run("invalid-provider", func(t *testing.T) {
+		invalidProvider := AlertProvider{DefaultConfig: Config{Token: "", ID: ""}}
+		if err := invalidProvider.Validate(); err == nil {
+			t.Error("provider shouldn't have been valid")
+		}
+	})
+	t.Run("valid-provider", func(t *testing.T) {
+		validProvider := AlertProvider{DefaultConfig: Config{Token: "123456:ABC-DEF1234ghIkl-zyx57W2v1u123ew11", ID: "12345678"}}
+		if err := validProvider.Validate(); err != nil {
+			t.Error("provider should've been valid")
+		}
+	})
+	t.Run("invalid-provider-override-nonexist-group", func(t *testing.T) {
+		invalidProvider := AlertProvider{DefaultConfig: Config{Token: "123456:ABC-DEF1234ghIkl-zyx57W2v1u123ew11", ID: "12345678"}, Overrides: []*Override{{Config: Config{Token: "token", ID: "id"}}}}
+		if err := invalidProvider.Validate(); err == nil {
+			t.Error("provider shouldn't have been valid")
+		}
+	})
+	t.Run("invalid-provider-override-duplicate-group", func(t *testing.T) {
+		invalidProvider := AlertProvider{DefaultConfig: Config{Token: "123456:ABC-DEF1234ghIkl-zyx57W2v1u123ew11", ID: "12345678"}, Overrides: []*Override{{Group: "group1", Config: Config{Token: "token", ID: "id"}}, {Group: "group1", Config: Config{ID: "id2"}}}}
+		if err := invalidProvider.Validate(); err == nil {
+			t.Error("provider shouldn't have been valid")
+		}
+	})
+	t.Run("valid-provider-with-overrides", func(t *testing.T) {
+		validProvider := AlertProvider{DefaultConfig: Config{Token: "123456:ABC-DEF1234ghIkl-zyx57W2v1u123ew11", ID: "12345678"}, Overrides: []*Override{{Group: "group", Config: Config{Token: "token", ID: "id"}}}}
+		if err := validProvider.Validate(); err != nil {
+			t.Error("provider should've been valid")
+		}
+	})
+}
+
+func TestAlertProvider_Send(t *testing.T) {
+	defer client.InjectHTTPClient(nil)
+	firstDescription := "description-1"
+	secondDescription := "description-2"
+	scenarios := []struct {
+		Name             string
+		Provider         AlertProvider
+		Alert            alert.Alert
+		Resolved         bool
+		MockRoundTripper test.MockRoundTripper
+		ExpectedError    bool
+	}{
+		{
+			Name:     "triggered",
+			Provider: AlertProvider{DefaultConfig: Config{ID: "123", Token: "123456:ABC-DEF1234ghIkl-zyx57W2v1u123ew11"}},
+			Alert:    alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: false,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusOK, Body: http.NoBody}
+			}),
+			ExpectedError: false,
+		},
+		{
+			Name:     "triggered-error",
+			Provider: AlertProvider{DefaultConfig: Config{ID: "123", Token: "123456:ABC-DEF1234ghIkl-zyx57W2v1u123ew11"}},
+			Alert:    alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: false,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusInternalServerError, Body: http.NoBody}
+			}),
+			ExpectedError: true,
+		},
+		{
+			Name:     "resolved",
+			Provider: AlertProvider{DefaultConfig: Config{ID: "123", Token: "123456:ABC-DEF1234ghIkl-zyx57W2v1u123ew11"}},
+			Alert:    alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: true,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusOK, Body: http.NoBody}
+			}),
+			ExpectedError: false,
+		},
+		{
+			Name:     "resolved-error",
+			Provider: AlertProvider{DefaultConfig: Config{ID: "123", Token: "123456:ABC-DEF1234ghIkl-zyx57W2v1u123ew11"}},
+			Alert:    alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: true,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusInternalServerError, Body: http.NoBody}
+			}),
+			ExpectedError: true,
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			client.InjectHTTPClient(&http.Client{Transport: scenario.MockRoundTripper})
+			err := scenario.Provider.Send(
+				&endpoint.Endpoint{Name: "endpoint-name"},
+				&scenario.Alert,
+				&endpoint.Result{
+					ConditionResults: []*endpoint.ConditionResult{
+						{Condition: "[CONNECTED] == true", Success: scenario.Resolved},
+						{Condition: "[STATUS] == 200", Success: scenario.Resolved},
+					},
+				},
+				scenario.Resolved,
+			)
+			if scenario.ExpectedError && err == nil {
+				t.Error("expected error, got none")
+			}
+			if !scenario.ExpectedError && err != nil {
+				t.Error("expected no error, got", err.Error())
+			}
+		})
+	}
+}
+
+func TestAlertProvider_buildRequestBody(t *testing.T) {
+	firstDescription := "description-1"
+	secondDescription := "description-2"
+	scenarios := []struct {
+		Name         string
+		Provider     AlertProvider
+		Alert        alert.Alert
+		NoConditions bool
+		Resolved     bool
+		ExpectedBody string
+	}{
+		{
+			Name:         "triggered",
+			Provider:     AlertProvider{DefaultConfig: Config{ID: "123"}},
+			Alert:        alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     false,
+			ExpectedBody: "{\"chat_id\":\"123\",\"text\":\"⛑ *Gatus* \\nAn alert for *endpoint-name* has been triggered:\\n—\\n    _healthcheck failed 3 time(s) in a row_\\n—   \\n*Description* \\n_description-1_  \\n\\n*Condition results*\\n❌ - `[CONNECTED] == true`\\n❌ - `[STATUS] == 200`\\n\",\"parse_mode\":\"MARKDOWN\"}",
+		},
+		{
+			Name:         "resolved",
+			Provider:     AlertProvider{DefaultConfig: Config{ID: "123"}},
+			Alert:        alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     true,
+			ExpectedBody: "{\"chat_id\":\"123\",\"text\":\"⛑ *Gatus* \\nAn alert for *endpoint-name* has been resolved:\\n—\\n    _healthcheck passing successfully 5 time(s) in a row_\\n—   \\n*Description* \\n_description-2_  \\n\\n*Condition results*\\n✅ - `[CONNECTED] == true`\\n✅ - `[STATUS] == 200`\\n\",\"parse_mode\":\"MARKDOWN\"}",
+		},
+		{
+			Name:         "resolved-with-no-conditions",
+			NoConditions: true,
+			Provider:     AlertProvider{DefaultConfig: Config{ID: "123"}},
+			Alert:        alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     true,
+			ExpectedBody: "{\"chat_id\":\"123\",\"text\":\"⛑ *Gatus* \\nAn alert for *endpoint-name* has been resolved:\\n—\\n    _healthcheck passing successfully 5 time(s) in a row_\\n—   \\n*Description* \\n_description-2_  \\n\",\"parse_mode\":\"MARKDOWN\"}",
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			var conditionResults []*endpoint.ConditionResult
+			if !scenario.NoConditions {
+				conditionResults = []*endpoint.ConditionResult{
+					{Condition: "[CONNECTED] == true", Success: scenario.Resolved},
+					{Condition: "[STATUS] == 200", Success: scenario.Resolved},
+				}
+			}
+			body := scenario.Provider.buildRequestBody(
+				&scenario.Provider.DefaultConfig,
+				&endpoint.Endpoint{Name: "endpoint-name"},
+				&scenario.Alert,
+				&endpoint.Result{ConditionResults: conditionResults},
+				scenario.Resolved,
+			)
+			if string(body) != scenario.ExpectedBody {
+				t.Errorf("expected:\n%s\ngot:\n%s", scenario.ExpectedBody, body)
+			}
+			out := make(map[string]interface{})
+			if err := json.Unmarshal(body, &out); err != nil {
+				t.Error("expected body to be valid JSON, got error:", err.Error())
+			}
+		})
+	}
+}
+
+func TestAlertProvider_GetDefaultAlert(t *testing.T) {
+	if (&AlertProvider{DefaultAlert: &alert.Alert{}}).GetDefaultAlert() == nil {
+		t.Error("expected default alert to be not nil")
+	}
+	if (&AlertProvider{DefaultAlert: nil}).GetDefaultAlert() != nil {
+		t.Error("expected default alert to be nil")
+	}
+}
+
+func TestAlertProvider_GetConfig(t *testing.T) {
+	t.Run("get-token-with-override", func(t *testing.T) {
+		provider := AlertProvider{DefaultConfig: Config{Token: "123456:ABC-DEF1234ghIkl-zyx57W2v1u123ew11", ID: "12345678"}, Overrides: []*Override{{Group: "group", Config: Config{Token: "groupToken", ID: "overrideID"}}}}
+		cfg, err := provider.GetConfig("group", &alert.Alert{})
+		if err != nil {
+			t.Error("expected no error, got", err)
+		}
+		if cfg.Token != "groupToken" {
+			t.Error("token should have been 'groupToken'")
+		}
+		if cfg.ID != "overrideID" {
+			t.Error("id should have been 'overrideID'")
+		}
+	})
+	t.Run("get-default-token-with-overridden-id", func(t *testing.T) {
+		provider := AlertProvider{DefaultConfig: Config{Token: "123456:ABC-DEF1234ghIkl-zyx57W2v1u123ew11", ID: "12345678"}, Overrides: []*Override{{Group: "group", Config: Config{ID: "overrideID"}}}}
+		cfg, err := provider.GetConfig("group", &alert.Alert{})
+		if err != nil {
+			t.Error("expected no error, got", err)
+		}
+		if cfg.Token != provider.DefaultConfig.Token {
+			t.Error("token should have been the default token")
+		}
+		if cfg.ID != "overrideID" {
+			t.Error("id should have been 'overrideID'")
+		}
+	})
+	t.Run("get-default-token-with-overridden-token", func(t *testing.T) {
+		provider := AlertProvider{DefaultConfig: Config{Token: "123456:ABC-DEF1234ghIkl-zyx57W2v1u123ew11", ID: "12345678"}, Overrides: []*Override{{Group: "group", Config: Config{Token: "groupToken"}}}}
+		cfg, err := provider.GetConfig("group", &alert.Alert{})
+		if err != nil {
+			t.Error("expected no error, got", err)
+		}
+		if cfg.Token != "groupToken" {
+			t.Error("token should have been 'groupToken'")
+		}
+		if cfg.ID != provider.DefaultConfig.ID {
+			t.Error("id should have been the default id")
+		}
+	})
+	t.Run("get-default-token-with-overridden-token-and-alert-token-override", func(t *testing.T) {
+		provider := AlertProvider{DefaultConfig: Config{Token: "123456:ABC-DEF1234ghIkl-zyx57W2v1u123ew11", ID: "12345678"}, Overrides: []*Override{{Group: "group", Config: Config{Token: "groupToken"}}}}
+		alert := &alert.Alert{ProviderOverride: map[string]any{"token": "alertToken"}}
+		cfg, err := provider.GetConfig("group", alert)
+		if err != nil {
+			t.Error("expected no error, got", err)
+		}
+		if cfg.Token != "alertToken" {
+			t.Error("token should have been 'alertToken'")
+		}
+		if cfg.ID != provider.DefaultConfig.ID {
+			t.Error("id should have been the default id")
+		}
+		// Test ValidateOverrides as well, since it really just calls GetConfig
+		if err = provider.ValidateOverrides("group", alert); err != nil {
+			t.Errorf("unexpected error: %s", err)
+		}
+	})
+}

alerting/provider/twilio/twilio.go

@@ -0,0 +1,141 @@
+package twilio
+
+import (
+	"bytes"
+	"encoding/base64"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+	"net/url"
+
+	"github.com/TwiN/gatus/v5/alerting/alert"
+	"github.com/TwiN/gatus/v5/client"
+	"github.com/TwiN/gatus/v5/config/endpoint"
+	"gopkg.in/yaml.v3"
+)
+
+var (
+	ErrSIDNotSet   = errors.New("sid not set")
+	ErrTokenNotSet = errors.New("token not set")
+	ErrFromNotSet  = errors.New("from not set")
+	ErrToNotSet    = errors.New("to not set")
+)
+
+type Config struct {
+	SID   string `yaml:"sid"`
+	Token string `yaml:"token"`
+	From  string `yaml:"from"`
+	To    string `yaml:"to"`
+}
+
+func (cfg *Config) Validate() error {
+	if len(cfg.SID) == 0 {
+		return ErrSIDNotSet
+	}
+	if len(cfg.Token) == 0 {
+		return ErrTokenNotSet
+	}
+	if len(cfg.From) == 0 {
+		return ErrFromNotSet
+	}
+	if len(cfg.To) == 0 {
+		return ErrToNotSet
+	}
+	return nil
+}
+
+func (cfg *Config) Merge(override *Config) {
+	if len(override.SID) > 0 {
+		cfg.SID = override.SID
+	}
+	if len(override.Token) > 0 {
+		cfg.Token = override.Token
+	}
+	if len(override.From) > 0 {
+		cfg.From = override.From
+	}
+	if len(override.To) > 0 {
+		cfg.To = override.To
+	}
+}
+
+// AlertProvider is the configuration necessary for sending an alert using Twilio
+type AlertProvider struct {
+	DefaultConfig Config `yaml:",inline"`
+
+	// DefaultAlert is the default alert configuration to use for endpoints with an alert of the appropriate type
+	DefaultAlert *alert.Alert `yaml:"default-alert,omitempty"`
+}
+
+// Validate the provider's configuration
+func (provider *AlertProvider) Validate() error {
+	return provider.DefaultConfig.Validate()
+}
+
+// Send an alert using the provider
+func (provider *AlertProvider) Send(ep *endpoint.Endpoint, alert *alert.Alert, result *endpoint.Result, resolved bool) error {
+	cfg, err := provider.GetConfig(ep.Group, alert)
+	if err != nil {
+		return err
+	}
+	buffer := bytes.NewBuffer([]byte(provider.buildRequestBody(cfg, ep, alert, result, resolved)))
+	request, err := http.NewRequest(http.MethodPost, fmt.Sprintf("https://api.twilio.com/2010-04-01/Accounts/%s/Messages.json", cfg.SID), buffer)
+	if err != nil {
+		return err
+	}
+	request.Header.Set("Content-Type", "application/x-www-form-urlencoded")
+	request.Header.Set("Authorization", fmt.Sprintf("Basic %s", base64.StdEncoding.EncodeToString([]byte(cfg.SID+":"+cfg.Token))))
+	response, err := client.GetHTTPClient(nil).Do(request)
+	if err != nil {
+		return err
+	}
+	defer response.Body.Close()
+	if response.StatusCode > 399 {
+		body, _ := io.ReadAll(response.Body)
+		return fmt.Errorf("call to provider alert returned status code %d: %s", response.StatusCode, string(body))
+	}
+	return err
+}
+
+// buildRequestBody builds the request body for the provider
+func (provider *AlertProvider) buildRequestBody(cfg *Config, ep *endpoint.Endpoint, alert *alert.Alert, result *endpoint.Result, resolved bool) string {
+	var message string
+	if resolved {
+		message = fmt.Sprintf("RESOLVED: %s - %s", ep.DisplayName(), alert.GetDescription())
+	} else {
+		message = fmt.Sprintf("TRIGGERED: %s - %s", ep.DisplayName(), alert.GetDescription())
+	}
+	return url.Values{
+		"To":   {cfg.To},
+		"From": {cfg.From},
+		"Body": {message},
+	}.Encode()
+}
+
+// GetDefaultAlert returns the provider's default alert configuration
+func (provider *AlertProvider) GetDefaultAlert() *alert.Alert {
+	return provider.DefaultAlert
+}
+
+// GetConfig returns the configuration for the provider with the overrides applied
+func (provider *AlertProvider) GetConfig(group string, alert *alert.Alert) (*Config, error) {
+	cfg := provider.DefaultConfig
+	// Handle alert overrides
+	if len(alert.ProviderOverride) != 0 {
+		overrideConfig := Config{}
+		if err := yaml.Unmarshal(alert.ProviderOverrideAsBytes(), &overrideConfig); err != nil {
+			return nil, err
+		}
+		cfg.Merge(&overrideConfig)
+	}
+	// Validate the configuration
+	err := cfg.Validate()
+	return &cfg, err
+}
+
+// ValidateOverrides validates the alert's provider override and, if present, the group override
+func (provider *AlertProvider) ValidateOverrides(group string, alert *alert.Alert) error {
+	_, err := provider.GetConfig(group, alert)
+	return err
+}

alerting/provider/twilio/twilio_test.go

@@ -0,0 +1,211 @@
+package twilio
+
+import (
+	"net/http"
+	"testing"
+
+	"github.com/TwiN/gatus/v5/alerting/alert"
+	"github.com/TwiN/gatus/v5/client"
+	"github.com/TwiN/gatus/v5/config/endpoint"
+	"github.com/TwiN/gatus/v5/test"
+)
+
+func TestTwilioAlertProvider_IsValid(t *testing.T) {
+	invalidProvider := AlertProvider{}
+	if err := invalidProvider.Validate(); err == nil {
+		t.Error("provider shouldn't have been valid")
+	}
+	validProvider := AlertProvider{
+		DefaultConfig: Config{
+			SID:   "1",
+			Token: "1",
+			From:  "1",
+			To:    "1",
+		},
+	}
+	if err := validProvider.Validate(); err != nil {
+		t.Error("provider should've been valid")
+	}
+}
+
+func TestAlertProvider_Send(t *testing.T) {
+	defer client.InjectHTTPClient(nil)
+	firstDescription := "description-1"
+	secondDescription := "description-2"
+	scenarios := []struct {
+		Name             string
+		Provider         AlertProvider
+		Alert            alert.Alert
+		Resolved         bool
+		MockRoundTripper test.MockRoundTripper
+		ExpectedError    bool
+	}{
+		{
+			Name:     "triggered",
+			Provider: AlertProvider{DefaultConfig: Config{SID: "1", Token: "2", From: "3", To: "4"}},
+			Alert:    alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: false,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusOK, Body: http.NoBody}
+			}),
+			ExpectedError: false,
+		},
+		{
+			Name:     "triggered-error",
+			Provider: AlertProvider{DefaultConfig: Config{SID: "1", Token: "2", From: "3", To: "4"}},
+			Alert:    alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: false,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusInternalServerError, Body: http.NoBody}
+			}),
+			ExpectedError: true,
+		},
+		{
+			Name:     "resolved",
+			Provider: AlertProvider{DefaultConfig: Config{SID: "1", Token: "2", From: "3", To: "4"}},
+			Alert:    alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: true,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusOK, Body: http.NoBody}
+			}),
+			ExpectedError: false,
+		},
+		{
+			Name:     "resolved-error",
+			Provider: AlertProvider{DefaultConfig: Config{SID: "1", Token: "2", From: "3", To: "4"}},
+			Alert:    alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: true,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusInternalServerError, Body: http.NoBody}
+			}),
+			ExpectedError: true,
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			client.InjectHTTPClient(&http.Client{Transport: scenario.MockRoundTripper})
+			err := scenario.Provider.Send(
+				&endpoint.Endpoint{Name: "endpoint-name"},
+				&scenario.Alert,
+				&endpoint.Result{
+					ConditionResults: []*endpoint.ConditionResult{
+						{Condition: "[CONNECTED] == true", Success: scenario.Resolved},
+						{Condition: "[STATUS] == 200", Success: scenario.Resolved},
+					},
+				},
+				scenario.Resolved,
+			)
+			if scenario.ExpectedError && err == nil {
+				t.Error("expected error, got none")
+			}
+			if !scenario.ExpectedError && err != nil {
+				t.Error("expected no error, got", err.Error())
+			}
+		})
+	}
+}
+
+func TestAlertProvider_buildRequestBody(t *testing.T) {
+	firstDescription := "description-1"
+	secondDescription := "description-2"
+	scenarios := []struct {
+		Name         string
+		Provider     AlertProvider
+		Alert        alert.Alert
+		Resolved     bool
+		ExpectedBody string
+	}{
+		{
+			Name:         "triggered",
+			Provider:     AlertProvider{DefaultConfig: Config{SID: "1", Token: "2", From: "3", To: "4"}},
+			Alert:        alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     false,
+			ExpectedBody: "Body=TRIGGERED%3A+endpoint-name+-+description-1&From=3&To=4",
+		},
+		{
+			Name:         "resolved",
+			Provider:     AlertProvider{DefaultConfig: Config{SID: "1", Token: "2", From: "3", To: "4"}},
+			Alert:        alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     true,
+			ExpectedBody: "Body=RESOLVED%3A+endpoint-name+-+description-2&From=3&To=4",
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			body := scenario.Provider.buildRequestBody(
+				&scenario.Provider.DefaultConfig,
+				&endpoint.Endpoint{Name: "endpoint-name"},
+				&scenario.Alert,
+				&endpoint.Result{
+					ConditionResults: []*endpoint.ConditionResult{
+						{Condition: "[CONNECTED] == true", Success: scenario.Resolved},
+						{Condition: "[STATUS] == 200", Success: scenario.Resolved},
+					},
+				},
+				scenario.Resolved,
+			)
+			if body != scenario.ExpectedBody {
+				t.Errorf("expected %s, got %s", scenario.ExpectedBody, body)
+			}
+		})
+	}
+}
+
+func TestAlertProvider_GetDefaultAlert(t *testing.T) {
+	if (&AlertProvider{DefaultAlert: &alert.Alert{}}).GetDefaultAlert() == nil {
+		t.Error("expected default alert to be not nil")
+	}
+	if (&AlertProvider{DefaultAlert: nil}).GetDefaultAlert() != nil {
+		t.Error("expected default alert to be nil")
+	}
+}
+
+func TestAlertProvider_GetConfig(t *testing.T) {
+	scenarios := []struct {
+		Name           string
+		Provider       AlertProvider
+		InputAlert     alert.Alert
+		ExpectedOutput Config
+	}{
+		{
+			Name: "provider-no-override-should-default",
+			Provider: AlertProvider{
+				DefaultConfig: Config{SID: "1", Token: "2", From: "3", To: "4"},
+			},
+			InputAlert:     alert.Alert{},
+			ExpectedOutput: Config{SID: "1", Token: "2", From: "3", To: "4"},
+		},
+		{
+			Name: "provider-with-alert-override",
+			Provider: AlertProvider{
+				DefaultConfig: Config{SID: "1", Token: "2", From: "3", To: "4"},
+			},
+			InputAlert:     alert.Alert{ProviderOverride: map[string]any{"sid": "5", "token": "6", "from": "7", "to": "8"}},
+			ExpectedOutput: Config{SID: "5", Token: "6", From: "7", To: "8"},
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			got, err := scenario.Provider.GetConfig("", &scenario.InputAlert)
+			if err != nil {
+				t.Error("expected no error, got:", err.Error())
+			}
+			if got.SID != scenario.ExpectedOutput.SID {
+				t.Errorf("expected SID to be %s, got %s", scenario.ExpectedOutput.SID, got.SID)
+			}
+			if got.Token != scenario.ExpectedOutput.Token {
+				t.Errorf("expected token to be %s, got %s", scenario.ExpectedOutput.Token, got.Token)
+			}
+			if got.From != scenario.ExpectedOutput.From {
+				t.Errorf("expected from to be %s, got %s", scenario.ExpectedOutput.From, got.From)
+			}
+			if got.To != scenario.ExpectedOutput.To {
+				t.Errorf("expected to to be %s, got %s", scenario.ExpectedOutput.To, got.To)
+			}
+			// Test ValidateOverrides as well, since it really just calls GetConfig
+			if err = scenario.Provider.ValidateOverrides("", &scenario.InputAlert); err != nil {
+				t.Errorf("unexpected error: %s", err)
+			}
+		})
+	}
+}

alerting/provider/zulip/zulip.go

@@ -0,0 +1,183 @@
+package zulip
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+	"net/url"
+
+	"github.com/TwiN/gatus/v5/alerting/alert"
+	"github.com/TwiN/gatus/v5/client"
+	"github.com/TwiN/gatus/v5/config/endpoint"
+	"gopkg.in/yaml.v3"
+)
+
+var (
+	ErrBotEmailNotSet         = errors.New("bot-email not set")
+	ErrBotAPIKeyNotSet        = errors.New("bot-api-key not set")
+	ErrDomainNotSet           = errors.New("domain not set")
+	ErrChannelIDNotSet        = errors.New("channel-id not set")
+	ErrDuplicateGroupOverride = errors.New("duplicate group override")
+)
+
+type Config struct {
+	BotEmail  string `yaml:"bot-email"`   // Email of the bot user
+	BotAPIKey string `yaml:"bot-api-key"` // API key of the bot user
+	Domain    string `yaml:"domain"`      // Domain of the Zulip server
+	ChannelID string `yaml:"channel-id"`  // ID of the channel to send the message to
+}
+
+func (cfg *Config) Validate() error {
+	if len(cfg.BotEmail) == 0 {
+		return ErrBotEmailNotSet
+	}
+	if len(cfg.BotAPIKey) == 0 {
+		return ErrBotAPIKeyNotSet
+	}
+	if len(cfg.Domain) == 0 {
+		return ErrDomainNotSet
+	}
+	if len(cfg.ChannelID) == 0 {
+		return ErrChannelIDNotSet
+	}
+	return nil
+}
+
+func (cfg *Config) Merge(override *Config) {
+	if len(override.BotEmail) > 0 {
+		cfg.BotEmail = override.BotEmail
+	}
+	if len(override.BotAPIKey) > 0 {
+		cfg.BotAPIKey = override.BotAPIKey
+	}
+	if len(override.Domain) > 0 {
+		cfg.Domain = override.Domain
+	}
+	if len(override.ChannelID) > 0 {
+		cfg.ChannelID = override.ChannelID
+	}
+}
+
+// AlertProvider is the configuration necessary for sending an alert using Zulip
+type AlertProvider struct {
+	DefaultConfig Config `yaml:",inline"`
+
+	// DefaultAlert is the default alert configuration to use for endpoints with an alert of the appropriate type
+	DefaultAlert *alert.Alert `yaml:"default-alert,omitempty"`
+
+	// Overrides is a list of Override that may be prioritized over the default configuration
+	Overrides []Override `yaml:"overrides,omitempty"`
+}
+
+// Override is a case under which the default integration is overridden
+type Override struct {
+	Group  string `yaml:"group"`
+	Config `yaml:",inline"`
+}
+
+// Validate the provider's configuration
+func (provider *AlertProvider) Validate() error {
+	registeredGroups := make(map[string]bool)
+	if provider.Overrides != nil {
+		for _, override := range provider.Overrides {
+			if isAlreadyRegistered := registeredGroups[override.Group]; isAlreadyRegistered || override.Group == "" {
+				return ErrDuplicateGroupOverride
+			}
+			registeredGroups[override.Group] = true
+		}
+	}
+	return provider.DefaultConfig.Validate()
+}
+
+// Send an alert using the provider
+func (provider *AlertProvider) Send(ep *endpoint.Endpoint, alert *alert.Alert, result *endpoint.Result, resolved bool) error {
+	cfg, err := provider.GetConfig(ep.Group, alert)
+	if err != nil {
+		return err
+	}
+	buffer := bytes.NewBufferString(provider.buildRequestBody(cfg, ep, alert, result, resolved))
+	zulipEndpoint := fmt.Sprintf("https://%s/api/v1/messages", cfg.Domain)
+	request, err := http.NewRequest(http.MethodPost, zulipEndpoint, buffer)
+	if err != nil {
+		return err
+	}
+	request.SetBasicAuth(cfg.BotEmail, cfg.BotAPIKey)
+	request.Header.Set("Content-Type", "application/x-www-form-urlencoded")
+	request.Header.Set("User-Agent", "Gatus")
+	response, err := client.GetHTTPClient(nil).Do(request)
+	if err != nil {
+		return err
+	}
+	defer response.Body.Close()
+	if response.StatusCode > 399 {
+		body, _ := io.ReadAll(response.Body)
+		return fmt.Errorf("call to provider alert returned status code %d: %s", response.StatusCode, string(body))
+	}
+	return nil
+}
+
+// buildRequestBody builds the request body for the provider
+func (provider *AlertProvider) buildRequestBody(cfg *Config, ep *endpoint.Endpoint, alert *alert.Alert, result *endpoint.Result, resolved bool) string {
+	var message string
+	if resolved {
+		message = fmt.Sprintf("An alert for **%s** has been resolved after passing successfully %d time(s) in a row", ep.DisplayName(), alert.SuccessThreshold)
+	} else {
+		message = fmt.Sprintf("An alert for **%s** has been triggered due to having failed %d time(s) in a row", ep.DisplayName(), alert.FailureThreshold)
+	}
+	if alertDescription := alert.GetDescription(); len(alertDescription) > 0 {
+		message += "\n> " + alertDescription + "\n"
+	}
+	for _, conditionResult := range result.ConditionResults {
+		var prefix string
+		if conditionResult.Success {
+			prefix = ":check:"
+		} else {
+			prefix = ":cross_mark:"
+		}
+		message += fmt.Sprintf("\n%s - `%s`", prefix, conditionResult.Condition)
+	}
+	return url.Values{
+		"type":    {"channel"},
+		"to":      {cfg.ChannelID},
+		"topic":   {"Gatus"},
+		"content": {message},
+	}.Encode()
+}
+
+// GetDefaultAlert returns the provider's default alert configuration
+func (provider *AlertProvider) GetDefaultAlert() *alert.Alert {
+	return provider.DefaultAlert
+}
+
+// GetConfig returns the configuration for the provider with the overrides applied
+func (provider *AlertProvider) GetConfig(group string, alert *alert.Alert) (*Config, error) {
+	cfg := provider.DefaultConfig
+	// Handle group overrides
+	if provider.Overrides != nil {
+		for _, override := range provider.Overrides {
+			if group == override.Group {
+				cfg.Merge(&override.Config)
+				break
+			}
+		}
+	}
+	// Handle alert overrides
+	if len(alert.ProviderOverride) != 0 {
+		overrideConfig := Config{}
+		if err := yaml.Unmarshal(alert.ProviderOverrideAsBytes(), &overrideConfig); err != nil {
+			return nil, err
+		}
+		cfg.Merge(&overrideConfig)
+	}
+	// Validate the configuration
+	err := cfg.Validate()
+	return &cfg, err
+}
+
+// ValidateOverrides validates the alert's provider override and, if present, the group override
+func (provider *AlertProvider) ValidateOverrides(group string, alert *alert.Alert) error {
+	_, err := provider.GetConfig(group, alert)
+	return err
+}

alerting/provider/zulip/zulip_test.go

@@ -0,0 +1,482 @@
+package zulip
+
+import (
+	"errors"
+	"fmt"
+	"net/http"
+	"net/url"
+	"testing"
+
+	"github.com/TwiN/gatus/v5/alerting/alert"
+	"github.com/TwiN/gatus/v5/client"
+	"github.com/TwiN/gatus/v5/config/endpoint"
+	"github.com/TwiN/gatus/v5/test"
+)
+
+func TestAlertProvider_Validate(t *testing.T) {
+	scenarios := []struct {
+		Name          string
+		AlertProvider AlertProvider
+		ExpectedError error
+	}{
+		{
+			Name:          "Empty provider",
+			AlertProvider: AlertProvider{},
+			ExpectedError: ErrBotEmailNotSet,
+		},
+		{
+			Name: "Empty channel id",
+			AlertProvider: AlertProvider{
+				DefaultConfig: Config{
+					BotEmail:  "something",
+					BotAPIKey: "something",
+					Domain:    "something",
+				},
+			},
+			ExpectedError: ErrChannelIDNotSet,
+		},
+		{
+			Name: "Empty domain",
+			AlertProvider: AlertProvider{
+				DefaultConfig: Config{
+					BotEmail:  "something",
+					BotAPIKey: "something",
+					ChannelID: "something",
+				},
+			},
+			ExpectedError: ErrDomainNotSet,
+		},
+		{
+			Name: "Empty bot api key",
+			AlertProvider: AlertProvider{
+				DefaultConfig: Config{
+					BotEmail:  "something",
+					Domain:    "something",
+					ChannelID: "something",
+				},
+			},
+			ExpectedError: ErrBotAPIKeyNotSet,
+		},
+		{
+			Name: "Empty bot email",
+			AlertProvider: AlertProvider{
+				DefaultConfig: Config{
+					BotAPIKey: "something",
+					Domain:    "something",
+					ChannelID: "something",
+				},
+			},
+			ExpectedError: ErrBotEmailNotSet,
+		},
+		{
+			Name: "Valid provider",
+			AlertProvider: AlertProvider{
+				DefaultConfig: Config{
+					BotEmail:  "something",
+					BotAPIKey: "something",
+					Domain:    "something",
+					ChannelID: "something",
+				},
+			},
+			ExpectedError: nil,
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			if err := scenario.AlertProvider.Validate(); !errors.Is(err, scenario.ExpectedError) {
+				t.Errorf("ExpectedError error %v, got %v", scenario.ExpectedError, err)
+			}
+		})
+	}
+}
+
+func TestAlertProvider_buildRequestBody(t *testing.T) {
+	basicConfig := Config{
+		BotEmail:  "bot-email",
+		BotAPIKey: "bot-api-key",
+		Domain:    "domain",
+		ChannelID: "channel-id",
+	}
+	alertDesc := "Description"
+	basicAlert := alert.Alert{
+		SuccessThreshold: 2,
+		FailureThreshold: 3,
+		Description:      &alertDesc,
+	}
+	testCases := []struct {
+		name          string
+		provider      AlertProvider
+		alert         alert.Alert
+		resolved      bool
+		hasConditions bool
+		expectedBody  url.Values
+	}{
+		{
+			name: "Resolved alert with no conditions",
+			provider: AlertProvider{
+				DefaultConfig: basicConfig,
+			},
+			alert:         basicAlert,
+			resolved:      true,
+			hasConditions: false,
+			expectedBody: url.Values{
+				"content": {`An alert for **endpoint-Name** has been resolved after passing successfully 2 time(s) in a row
+> Description
+`},
+				"to":    {"channel-id"},
+				"topic": {"Gatus"},
+				"type":  {"channel"},
+			},
+		},
+		{
+			name: "Resolved alert with conditions",
+			provider: AlertProvider{
+				DefaultConfig: basicConfig,
+			},
+			alert:         basicAlert,
+			resolved:      true,
+			hasConditions: true,
+			expectedBody: url.Values{
+				"content": {`An alert for **endpoint-Name** has been resolved after passing successfully 2 time(s) in a row
+> Description
+
+:check: - ` + "`[CONNECTED] == true`" + `
+:check: - ` + "`[STATUS] == 200`" + `
+:check: - ` + "`[BODY] != \"\"`"},
+				"to":    {"channel-id"},
+				"topic": {"Gatus"},
+				"type":  {"channel"},
+			},
+		},
+		{
+			name: "Failed alert with no conditions",
+			provider: AlertProvider{
+				DefaultConfig: basicConfig,
+			},
+			alert:         basicAlert,
+			resolved:      false,
+			hasConditions: false,
+			expectedBody: url.Values{
+				"content": {`An alert for **endpoint-Name** has been triggered due to having failed 3 time(s) in a row
+> Description
+`},
+				"to":    {"channel-id"},
+				"topic": {"Gatus"},
+				"type":  {"channel"},
+			},
+		},
+		{
+			name: "Failed alert with conditions",
+			provider: AlertProvider{
+				DefaultConfig: basicConfig,
+			},
+			alert:         basicAlert,
+			resolved:      false,
+			hasConditions: true,
+			expectedBody: url.Values{
+				"content": {`An alert for **endpoint-Name** has been triggered due to having failed 3 time(s) in a row
+> Description
+
+:cross_mark: - ` + "`[CONNECTED] == true`" + `
+:cross_mark: - ` + "`[STATUS] == 200`" + `
+:cross_mark: - ` + "`[BODY] != \"\"`"},
+				"to":    {"channel-id"},
+				"topic": {"Gatus"},
+				"type":  {"channel"},
+			},
+		},
+	}
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			var conditionResults []*endpoint.ConditionResult
+			if tc.hasConditions {
+				conditionResults = []*endpoint.ConditionResult{
+					{Condition: "[CONNECTED] == true", Success: tc.resolved},
+					{Condition: "[STATUS] == 200", Success: tc.resolved},
+					{Condition: "[BODY] != \"\"", Success: tc.resolved},
+				}
+			}
+			body := tc.provider.buildRequestBody(
+				&tc.provider.DefaultConfig,
+				&endpoint.Endpoint{Name: "endpoint-Name"},
+				&tc.alert,
+				&endpoint.Result{
+					ConditionResults: conditionResults,
+				},
+				tc.resolved,
+			)
+			valuesResult, err := url.ParseQuery(body)
+			if err != nil {
+				t.Error(err)
+			}
+			if fmt.Sprintf("%v", valuesResult) != fmt.Sprintf("%v", tc.expectedBody) {
+				t.Errorf("Expected body:\n%v\ngot:\n%v", tc.expectedBody, valuesResult)
+			}
+		})
+	}
+}
+
+func TestAlertProvider_GetDefaultAlert(t *testing.T) {
+	if (&AlertProvider{DefaultAlert: &alert.Alert{}}).GetDefaultAlert() == nil {
+		t.Error("ExpectedError default alert to be not nil")
+	}
+	if (&AlertProvider{DefaultAlert: nil}).GetDefaultAlert() != nil {
+		t.Error("ExpectedError default alert to be nil")
+	}
+}
+
+func TestAlertProvider_Send(t *testing.T) {
+	defer client.InjectHTTPClient(nil)
+	validateRequest := func(req *http.Request) {
+		if req.URL.String() != "https://custom-domain/api/v1/messages" {
+			t.Errorf("ExpectedError url https://custom-domain.zulipchat.com/api/v1/messages, got %s", req.URL.String())
+		}
+		if req.Method != http.MethodPost {
+			t.Errorf("ExpectedError POST request, got %s", req.Method)
+		}
+		if req.Header.Get("Content-Type") != "application/x-www-form-urlencoded" {
+			t.Errorf("ExpectedError Content-Type header to be application/x-www-form-urlencoded, got %s", req.Header.Get("Content-Type"))
+		}
+		if req.Header.Get("User-Agent") != "Gatus" {
+			t.Errorf("ExpectedError User-Agent header to be Gatus, got %s", req.Header.Get("User-Agent"))
+		}
+	}
+	basicConfig := Config{
+		BotEmail:  "bot-email",
+		BotAPIKey: "bot-api-key",
+		Domain:    "custom-domain",
+		ChannelID: "channel-id",
+	}
+	basicAlert := alert.Alert{
+		SuccessThreshold: 2,
+		FailureThreshold: 3,
+	}
+	testCases := []struct {
+		name             string
+		provider         AlertProvider
+		alert            alert.Alert
+		resolved         bool
+		mockRoundTripper test.MockRoundTripper
+		expectedError    bool
+	}{
+		{
+			name: "resolved",
+			provider: AlertProvider{
+				DefaultConfig: basicConfig,
+			},
+			alert:    basicAlert,
+			resolved: true,
+			mockRoundTripper: test.MockRoundTripper(func(req *http.Request) *http.Response {
+				validateRequest(req)
+				return &http.Response{StatusCode: http.StatusOK}
+			}),
+			expectedError: false,
+		},
+		{
+			name: "resolved error",
+			provider: AlertProvider{
+				DefaultConfig: basicConfig,
+			},
+			alert:    basicAlert,
+			resolved: true,
+			mockRoundTripper: test.MockRoundTripper(func(req *http.Request) *http.Response {
+				validateRequest(req)
+				return &http.Response{StatusCode: http.StatusInternalServerError}
+			}),
+			expectedError: true,
+		},
+		{
+			name: "triggered",
+			provider: AlertProvider{
+				DefaultConfig: basicConfig,
+			},
+			alert:    basicAlert,
+			resolved: false,
+			mockRoundTripper: test.MockRoundTripper(func(req *http.Request) *http.Response {
+				validateRequest(req)
+				return &http.Response{StatusCode: http.StatusOK}
+			}),
+			expectedError: false,
+		},
+		{
+			name: "triggered error",
+			provider: AlertProvider{
+				DefaultConfig: basicConfig,
+			},
+			alert:    basicAlert,
+			resolved: false,
+			mockRoundTripper: test.MockRoundTripper(func(req *http.Request) *http.Response {
+				validateRequest(req)
+				return &http.Response{StatusCode: http.StatusInternalServerError}
+			}),
+			expectedError: true,
+		},
+	}
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			client.InjectHTTPClient(&http.Client{Transport: tc.mockRoundTripper})
+			err := tc.provider.Send(
+				&endpoint.Endpoint{Name: "endpoint-Name"},
+				&tc.alert,
+				&endpoint.Result{
+					ConditionResults: []*endpoint.ConditionResult{
+						{Condition: "[CONNECTED] == true", Success: tc.resolved},
+						{Condition: "[STATUS] == 200", Success: tc.resolved},
+					},
+				},
+				tc.resolved,
+			)
+			if tc.expectedError && err == nil {
+				t.Error("ExpectedError error, got none")
+			}
+			if !tc.expectedError && err != nil {
+				t.Errorf("ExpectedError no error, got: %v", err)
+			}
+		})
+	}
+}
+
+func TestAlertProvider_GetConfig(t *testing.T) {
+	scenarios := []struct {
+		Name           string
+		Provider       AlertProvider
+		InputGroup     string
+		InputAlert     alert.Alert
+		ExpectedOutput Config
+	}{
+		{
+			Name: "provider-no-overrides",
+			Provider: AlertProvider{
+				DefaultConfig: Config{
+					BotEmail:  "default-bot-email",
+					BotAPIKey: "default-bot-api-key",
+					Domain:    "default-domain",
+					ChannelID: "default-channel-id",
+				},
+				Overrides: nil,
+			},
+			InputGroup: "group",
+			InputAlert: alert.Alert{},
+			ExpectedOutput: Config{
+				BotEmail:  "default-bot-email",
+				BotAPIKey: "default-bot-api-key",
+				Domain:    "default-domain",
+				ChannelID: "default-channel-id",
+			},
+		},
+		{
+			Name: "provider-with-override-specify-no-group-should-default",
+			Provider: AlertProvider{
+				DefaultConfig: Config{
+					BotEmail:  "default-bot-email",
+					BotAPIKey: "default-bot-api-key",
+					Domain:    "default-domain",
+					ChannelID: "default-channel-id",
+				},
+				Overrides: []Override{
+					{
+						Group:  "group",
+						Config: Config{ChannelID: "group-channel-id"},
+					},
+				},
+			},
+			InputGroup: "",
+			InputAlert: alert.Alert{},
+			ExpectedOutput: Config{
+				BotEmail:  "default-bot-email",
+				BotAPIKey: "default-bot-api-key",
+				Domain:    "default-domain",
+				ChannelID: "default-channel-id",
+			},
+		},
+		{
+			Name: "provider-with-override-specify-group-should-override",
+			Provider: AlertProvider{
+				DefaultConfig: Config{
+					BotEmail:  "default-bot-email",
+					BotAPIKey: "default-bot-api-key",
+					Domain:    "default-domain",
+					ChannelID: "default-channel-id",
+				},
+				Overrides: []Override{
+					{
+						Group: "group",
+						Config: Config{
+							BotEmail:  "group-bot-email",
+							BotAPIKey: "group-bot-api-key",
+							Domain:    "group-domain",
+							ChannelID: "group-channel-id",
+						},
+					},
+				},
+			},
+			InputGroup: "group",
+			InputAlert: alert.Alert{},
+			ExpectedOutput: Config{
+				BotEmail:  "group-bot-email",
+				BotAPIKey: "group-bot-api-key",
+				Domain:    "group-domain",
+				ChannelID: "group-channel-id",
+			},
+		},
+		{
+			Name: "provider-with-group-override-and-alert-override--alert-override-should-take-precedence",
+			Provider: AlertProvider{
+				DefaultConfig: Config{
+					BotEmail:  "default-bot-email",
+					BotAPIKey: "default-bot-api-key",
+					Domain:    "default-domain",
+					ChannelID: "default-channel-id",
+				},
+				Overrides: []Override{
+					{
+						Group: "group",
+						Config: Config{
+							BotEmail:  "group-bot-email",
+							BotAPIKey: "group-bot-api-key",
+							Domain:    "group-domain",
+							ChannelID: "group-channel-id",
+						},
+					},
+				},
+			},
+			InputGroup: "group",
+			InputAlert: alert.Alert{ProviderOverride: map[string]any{
+				"bot-email":   "alert-bot-email",
+				"bot-api-key": "alert-bot-api-key",
+				"domain":      "alert-domain",
+				"channel-id":  "alert-channel-id",
+			}},
+			ExpectedOutput: Config{
+				BotEmail:  "alert-bot-email",
+				BotAPIKey: "alert-bot-api-key",
+				Domain:    "alert-domain",
+				ChannelID: "alert-channel-id",
+			},
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			got, err := scenario.Provider.GetConfig(scenario.InputGroup, &scenario.InputAlert)
+			if err != nil {
+				t.Fatalf("unexpected error: %s", err)
+			}
+			if got.BotEmail != scenario.ExpectedOutput.BotEmail {
+				t.Errorf("expected %s, got %s", scenario.ExpectedOutput.BotEmail, got.BotEmail)
+			}
+			if got.BotAPIKey != scenario.ExpectedOutput.BotAPIKey {
+				t.Errorf("expected %s, got %s", scenario.ExpectedOutput.BotAPIKey, got.BotAPIKey)
+			}
+			if got.Domain != scenario.ExpectedOutput.Domain {
+				t.Errorf("expected %s, got %s", scenario.ExpectedOutput.Domain, got.Domain)
+			}
+			if got.ChannelID != scenario.ExpectedOutput.ChannelID {
+				t.Errorf("expected %s, got %s", scenario.ExpectedOutput.ChannelID, got.ChannelID)
+			}
+			// Test ValidateOverrides as well, since it really just calls GetConfig
+			if err = scenario.Provider.ValidateOverrides(scenario.InputGroup, &scenario.InputAlert); err != nil {
+				t.Errorf("unexpected error: %s", err)
+			}
+		})
+	}
+}