feat(alerting): Persist triggered alerts across application restart (#764)

* feat(alerting): Persist triggered alerts across application restart

Fixes #679

* test(alerting): Add numerous tests related to alerts

alerting/alert/alert.go

@@ -1,7 +1,10 @@
 package alert
 
 import (
+	"crypto/sha256"
+	"encoding/hex"
 	"errors"
+	"strconv"
 	"strings"
 )
 
@@ -26,6 +29,9 @@ type Alert struct {
 	// FailureThreshold is the number of failures in a row needed before triggering the alert
 	FailureThreshold int `yaml:"failure-threshold"`
 
+	// SuccessThreshold defines how many successful executions must happen in a row before an ongoing incident is marked as resolved
+	SuccessThreshold int `yaml:"success-threshold"`
+
 	// Description of the alert. Will be included in the alert sent.
 	//
 	// This is a pointer, because it is populated by YAML and we need to know whether it was explicitly set to a value
@@ -38,9 +44,6 @@ type Alert struct {
 	// or not for provider.ParseWithDefaultAlert to work. Use Alert.IsSendingOnResolved() for a non-pointer
 	SendOnResolved *bool `yaml:"send-on-resolved"`
 
-	// SuccessThreshold defines how many successful executions must happen in a row before an ongoing incident is marked as resolved
-	SuccessThreshold int `yaml:"success-threshold"`
-
 	// ResolveKey is an optional field that is used by some providers (i.e. PagerDuty's dedup_key) to resolve
 	// ongoing/triggered incidents
 	ResolveKey string `yaml:"-"`
@@ -94,3 +97,17 @@ func (alert *Alert) IsSendingOnResolved() bool {
 	}
 	return *alert.SendOnResolved
 }
+
+// Checksum returns a checksum of the alert
+// Used to determine which persisted triggered alert should be deleted on application start
+func (alert *Alert) Checksum() string {
+	hash := sha256.New()
+	hash.Write([]byte(string(alert.Type) + "_" +
+		strconv.FormatBool(alert.IsEnabled()) + "_" +
+		strconv.FormatBool(alert.IsSendingOnResolved()) + "_" +
+		strconv.Itoa(alert.SuccessThreshold) + "_" +
+		strconv.Itoa(alert.FailureThreshold) + "_" +
+		alert.GetDescription()),
+	)
+	return hex.EncodeToString(hash.Sum(nil))
+}

alerting/alert/alert_test.go

@@ -84,3 +84,109 @@ func TestAlert_IsSendingOnResolved(t *testing.T) {
 		t.Error("alert.IsSendingOnResolved() should've returned true, because SendOnResolved was set to true")
 	}
 }
+
+func TestAlert_Checksum(t *testing.T) {
+	description1, description2 := "a", "b"
+	yes, no := true, false
+	scenarios := []struct {
+		name     string
+		alert    Alert
+		expected string
+	}{
+		{
+			name: "barebone",
+			alert: Alert{
+				Type: TypeDiscord,
+			},
+			expected: "fed0580e44ed5701dbba73afa1f14b2c53ca5a7b8067a860441c212916057fe3",
+		},
+		{
+			name: "with-description-1",
+			alert: Alert{
+				Type:        TypeDiscord,
+				Description: &description1,
+			},
+			expected: "005f407ebe506e74a4aeb46f74c28b376debead7011e1b085da3840f72ba9707",
+		},
+		{
+			name: "with-description-2",
+			alert: Alert{
+				Type:        TypeDiscord,
+				Description: &description2,
+			},
+			expected: "3c2c4a9570cdc614006993c21f79a860a7f5afea10cf70d1a79d3c49342ef2c8",
+		},
+		{
+			name: "with-description-2-and-enabled-false",
+			alert: Alert{
+				Type:        TypeDiscord,
+				Enabled:     &no,
+				Description: &description2,
+			},
+			expected: "837945c2b4cd5e961db3e63e10c348d4f1c3446ba68cf5a48e35a1ae22cf0c22",
+		},
+		{
+			name: "with-description-2-and-enabled-true",
+			alert: Alert{
+				Type:        TypeDiscord,
+				Enabled:     &yes, // it defaults to true if not set, but just to make sure
+				Description: &description2,
+			},
+			expected: "3c2c4a9570cdc614006993c21f79a860a7f5afea10cf70d1a79d3c49342ef2c8",
+		},
+		{
+			name: "with-description-2-and-enabled-true-and-send-on-resolved-true",
+			alert: Alert{
+				Type:           TypeDiscord,
+				Enabled:        &yes,
+				SendOnResolved: &yes,
+				Description:    &description2,
+			},
+			expected: "bf1436995a880eb4a352c74c5dfee1f1b5ff6b9fc55aef9bf411b3631adfd80c",
+		},
+		{
+			name: "with-description-2-and-failure-threshold-7",
+			alert: Alert{
+				Type:             TypeSlack,
+				FailureThreshold: 7,
+				Description:      &description2,
+			},
+			expected: "8bd479e18bda393d4c924f5a0d962e825002168dedaa88b445e435db7bacffd3",
+		},
+		{
+			name: "with-description-2-and-failure-threshold-9",
+			alert: Alert{
+				Type:             TypeSlack,
+				FailureThreshold: 9,
+				Description:      &description2,
+			},
+			expected: "5abdfce5236e344996d264d526e769c07cb0d3d329a999769a1ff84b157ca6f1",
+		},
+		{
+			name: "with-description-2-and-success-threshold-5",
+			alert: Alert{
+				Type:             TypeSlack,
+				SuccessThreshold: 7,
+				Description:      &description2,
+			},
+			expected: "c0000e73626b80e212cfc24830de7094568f648e37f3e16f9e68c7f8ef75c34c",
+		},
+		{
+			name: "with-description-2-and-success-threshold-1",
+			alert: Alert{
+				Type:             TypeSlack,
+				SuccessThreshold: 1,
+				Description:      &description2,
+			},
+			expected: "5c28963b3a76104cfa4a0d79c89dd29ec596c8cfa4b1af210ec83d6d41587b5f",
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.name, func(t *testing.T) {
+			scenario.alert.ValidateAndSetDefaults()
+			if checksum := scenario.alert.Checksum(); checksum != scenario.expected {
+				t.Errorf("expected checksum %v, got %v", scenario.expected, checksum)
+			}
+		})
+	}
+}