Close #18: Support monitoring TCP services

core/condition_test.go

@@ -265,3 +265,21 @@ func TestCondition_evaluateWithStatusPatternFailure(t *testing.T) {
 		t.Errorf("Condition '%s' should have been a failure", condition)
 	}
 }
+
+func TestCondition_evaluateWithConnected(t *testing.T) {
+	condition := Condition("[CONNECTED] == true")
+	result := &Result{Connected: true}
+	condition.evaluate(result)
+	if !result.ConditionResults[0].Success {
+		t.Errorf("Condition '%s' should have been a success", condition)
+	}
+}
+
+func TestCondition_evaluateWithConnectedFailure(t *testing.T) {
+	condition := Condition("[CONNECTED] == true")
+	result := &Result{Connected: false}
+	condition.evaluate(result)
+	if result.ConditionResults[0].Success {
+		t.Errorf("Condition '%s' should have been a failure", condition)
+	}
+}

core/service.go

@@ -9,6 +9,7 @@ import (
 	"net"
 	"net/http"
 	"net/url"
+	"strings"
 	"time"
 )
 
@@ -136,19 +137,30 @@ func (service *Service) getIp(result *Result) {
 }
 
 func (service *Service) call(result *Result) {
-	request := service.buildRequest()
-	startTime := time.Now()
-	response, err := client.GetHttpClient(service.Insecure).Do(request)
-	if err != nil {
-		result.Duration = time.Since(startTime)
-		result.Errors = append(result.Errors, err.Error())
-		return
+	isServiceTcp := strings.HasPrefix(service.Url, "tcp://")
+	var request *http.Request
+	var response *http.Response
+	var err error
+	if !isServiceTcp {
+		request = service.buildRequest()
 	}
-	result.Duration = time.Since(startTime)
-	result.HttpStatus = response.StatusCode
-	result.Body, err = ioutil.ReadAll(response.Body)
-	if err != nil {
-		result.Errors = append(result.Errors, err.Error())
+	startTime := time.Now()
+	if isServiceTcp {
+		result.Connected = client.CanCreateConnectionToTcpService(strings.TrimPrefix(service.Url, "tcp://"))
+		result.Duration = time.Since(startTime)
+	} else {
+		response, err = client.GetHttpClient(service.Insecure).Do(request)
+		result.Duration = time.Since(startTime)
+		if err != nil {
+			result.Errors = append(result.Errors, err.Error())
+			return
+		}
+		result.HttpStatus = response.StatusCode
+		result.Connected = response.StatusCode > 0
+		result.Body, err = ioutil.ReadAll(response.Body)
+		if err != nil {
+			result.Errors = append(result.Errors, err.Error())
+		}
 	}
 }
 

core/types.go

@@ -9,16 +9,37 @@ type HealthStatus struct {
 	Message string `json:"message,omitempty"`
 }
 
+// Result of the evaluation of a Service
 type Result struct {
-	HttpStatus       int                `json:"status"`
-	Body             []byte             `json:"-"`
-	Hostname         string             `json:"hostname"`
-	Ip               string             `json:"-"`
-	Duration         time.Duration      `json:"duration"`
-	Errors           []string           `json:"errors"`
+	// HttpStatus is the HTTP response status code
+	HttpStatus int `json:"status"`
+
+	// Body is the response body
+	Body []byte `json:"-"`
+
+	// Hostname extracted from the Service Url
+	Hostname string `json:"hostname"`
+
+	// Ip resolved from the Service Url
+	Ip string `json:"-"`
+
+	// Connected whether a connection to the host was established successfully
+	Connected bool `json:"-"`
+
+	// Duration time that the request took
+	Duration time.Duration `json:"duration"`
+
+	// Errors encountered during the evaluation of the service's health
+	Errors []string `json:"errors"`
+
+	// ConditionResults results of the service's conditions
 	ConditionResults []*ConditionResult `json:"condition-results"`
-	Success          bool               `json:"success"`
-	Timestamp        time.Time          `json:"timestamp"`
+
+	// Success whether the result signifies a success or not
+	Success bool `json:"success"`
+
+	// Timestamp when the request was sent
+	Timestamp time.Time `json:"timestamp"`
 }
 
 type ConditionResult struct {

core/util.go

@@ -12,6 +12,7 @@ const (
 	IPPlaceHolder           = "[IP]"
 	ResponseTimePlaceHolder = "[RESPONSE_TIME]"
 	BodyPlaceHolder         = "[BODY]"
+	ConnectedPlaceHolder    = "[CONNECTED]"
 
 	LengthFunctionPrefix  = "len("
 	PatternFunctionPrefix = "pat("
@@ -35,6 +36,8 @@ func sanitizeAndResolve(list []string, result *Result) []string {
 			element = strconv.Itoa(int(result.Duration.Milliseconds()))
 		case BodyPlaceHolder:
 			element = body
+		case ConnectedPlaceHolder:
+			element = strconv.FormatBool(result.Connected)
 		default:
 			// if contains the BodyPlaceHolder, then evaluate json path
 			if strings.Contains(element, BodyPlaceHolder) {