Make Alerta event property configurable (influxdata#461)

* Make Alerta event property configurable

* Provide only the idInfo struct when executing the event template

This is so that the user cannot create an event with data that
changes depending on the state of the alert.

CHANGELOG.md

@@ -53,6 +53,7 @@ For example, let's say we want to store all data that triggered an alert in Infl
 - [#426](https://github.com/influxdata/kapacitor/issues/426): Add `skip-format` query parameter to the `GET /task` endpoint so that returned TICKscript content is left unmodified from the user input.
 - [#388](https://github.com/influxdata/kapacitor/issues/388): The duration of an alert is now tracked and exposed as part of the alert data as well as can be set as a field via `.durationField('duration')`.
 - [#486](https://github.com/influxdata/kapacitor/pull/486): Default config file location.
+- [#461](https://github.com/influxdata/kapacitor/pull/461): Make Alerta `event` property configurable.
 
 ### Bugfixes
 

alert.go

@@ -232,6 +232,10 @@ func newAlertNode(et *ExecutingTask, n *pipeline.AlertNode, l *log.Logger) (an *
 		if err != nil {
 			return nil, err
 		}
+		evtmpl, err := text.New("event").Parse(alerta.Event)
+		if err != nil {
+			return nil, err
+		}
 		etmpl, err := text.New("environment").Parse(alerta.Environment)
 		if err != nil {
 			return nil, err
@@ -247,6 +251,7 @@ func newAlertNode(et *ExecutingTask, n *pipeline.AlertNode, l *log.Logger) (an *
 		ai := alertaHandler{
 			AlertaHandler:   alerta,
 			resourceTmpl:    rtmpl,
+			eventTmpl:       evtmpl,
 			environmentTmpl: etmpl,
 			groupTmpl:       gtmpl,
 			valueTmpl:       vtmpl,
@@ -873,6 +878,7 @@ type alertaHandler struct {
 	*pipeline.AlertaHandler
 
 	resourceTmpl    *text.Template
+	eventTmpl       *text.Template
 	environmentTmpl *text.Template
 	valueTmpl       *text.Template
 	groupTmpl       *text.Template
@@ -907,6 +913,22 @@ func (a *AlertNode) handleAlerta(alerta alertaHandler, ad *AlertData) {
 	resource := buf.String()
 	buf.Reset()
 
+	type eventData struct {
+		idInfo
+		ID string
+	}
+	data := eventData{
+		idInfo: ad.info.messageInfo.idInfo,
+		ID:     ad.ID,
+	}
+	err = alerta.eventTmpl.Execute(&buf, data)
+	if err != nil {
+		a.logger.Printf("E! failed to evaluate Alerta Event template %s", alerta.Event)
+		return
+	}
+	event := buf.String()
+	buf.Reset()
+
 	err = alerta.environmentTmpl.Execute(&buf, ad.info)
 	if err != nil {
 		a.logger.Printf("E! failed to evaluate Alerta Environment template %s", alerta.Environment)
@@ -938,7 +960,7 @@ func (a *AlertNode) handleAlerta(alerta alertaHandler, ad *AlertData) {
 	err = a.et.tm.AlertaService.Alert(
 		alerta.Token,
 		resource,
-		ad.ID,
+		event,
 		environment,
 		severity,
 		group,

integrations/streamer_test.go

@@ -2707,6 +2707,9 @@ func TestStream_AlertAlerta(t *testing.T) {
 			if exp := "cpu"; pd.Resource != exp {
 				t.Errorf("unexpected resource got %s exp %s", pd.Resource, exp)
 			}
+			if exp := "serverA"; pd.Event != exp {
+				t.Errorf("unexpected event got %s exp %s", pd.Event, exp)
+			}
 			if exp := "production"; pd.Environment != exp {
 				t.Errorf("unexpected environment got %s exp %s", pd.Environment, exp)
 			}
@@ -2726,9 +2729,12 @@ func TestStream_AlertAlerta(t *testing.T) {
 			if exp := "/alert?api-key=anothertesttoken"; r.URL.String() != exp {
 				t.Errorf("unexpected url got %s exp %s", r.URL.String(), exp)
 			}
-			if exp := "resource: cpu"; pd.Resource != exp {
+			if exp := "resource: serverA"; pd.Resource != exp {
 				t.Errorf("unexpected resource got %s exp %s", pd.Resource, exp)
 			}
+			if exp := "event: TestStream_Alert"; pd.Event != exp {
+				t.Errorf("unexpected event got %s exp %s", pd.Event, exp)
+			}
 			if exp := "serverA"; pd.Environment != exp {
 				t.Errorf("unexpected environment got %s exp %s", pd.Environment, exp)
 			}
@@ -2745,9 +2751,6 @@ func TestStream_AlertAlerta(t *testing.T) {
 				t.Errorf("unexpected origin got %s exp %s", pd.Origin, exp)
 			}
 		}
-		if exp := "serverA"; pd.Event != exp {
-			t.Errorf("unexpected event got %s exp %s", pd.Event, exp)
-		}
 		if exp := "kapacitor/cpu/serverA is CRITICAL @1971-01-01 00:00:10 +0000 UTC"; pd.Text != exp {
 			t.Errorf("unexpected text got %s exp %s", pd.Text, exp)
 		}
@@ -2775,7 +2778,8 @@ stream
 			.environment('production')
 		.alerta()
 			.token('anothertesttoken')
-			.resource('resource: {{ .Name }}')
+			.resource('resource: {{ index .Tags "host" }}')
+			.event('event: {{ .TaskName }}')
 			.environment('{{ index .Tags "host" }}')
 			.origin('override')
 			.group('{{ .ID }}')

pipeline/alert.go

@@ -751,13 +751,15 @@ func (a *AlertNode) Alerta() *AlertaHandler {
 	alerta := &AlertaHandler{
 		AlertNode: a,
 		Resource:  defaultAlertaResource,
+		Event:     defaultAlertaEvent,
 		Group:     defaultAlertaGroup,
 	}
 	a.AlertaHandlers = append(a.AlertaHandlers, alerta)
 	return alerta
 }
 
 const defaultAlertaResource = "{{ .Name }}"
+const defaultAlertaEvent = "{{ .ID }}"
 const defaultAlertaGroup = "{{ .Group }}"
 
 // tick:embedded:AlertNode.Alerta
@@ -773,6 +775,11 @@ type AlertaHandler struct {
 	// Default: {{ .Name }}
 	Resource string
 
+	// Alerta event.
+	// Can be a template and has access to the same data as the idInfo property.
+	// Default: {{ .ID }}
+	Event string
+
 	// Alerta environment.
 	// Can be a template and has access to the same data as the AlertNode.Details property.
 	// Defaut is set from the configuration.