template: export GroupKey on template.Data

notify/util.go

@@ -213,6 +213,11 @@ func GetTemplateData(ctx context.Context, tmpl *template.Template, alerts []*typ
 		notificationReason = ReasonUnknown
 	}
 	data := tmpl.Data(recv, groupLabels, routeLabels, notificationReason.String(), alerts...)
+	// Group key is optional for some callers (e.g. tests); populate when present
+	// so templates and webhook-style consumers can access .GroupKey.
+	if groupKey, ok := GroupKey(ctx); ok {
+		data.GroupKey = groupKey
+	}
 	// Route labels are pre-rendered by the dispatcher; don't execute them again.
 	template.MarkRouteLabelsRendered(data)
 	return data

notify/util_test.go

@@ -244,6 +244,7 @@ func TestGetTemplateDataWithRouteLabels(t *testing.T) {
 
 	data := GetTemplateData(ctx, tmpl, nil, promslog.NewNopLogger())
 
+	require.Equal(t, "test-key", data.GroupKey)
 	require.Equal(t, "ops", data.RouteLabels["team"])
 	require.Equal(t, "value is {{ $value }}", data.RouteLabels["desc"])
 
@@ -253,6 +254,34 @@ func TestGetTemplateDataWithRouteLabels(t *testing.T) {
 	require.Equal(t, "ops|value is {{ $value }}", got)
 }
 
+func TestGetTemplateDataGroupKey(t *testing.T) {
+	tmpl, err := template.New()
+	require.NoError(t, err)
+	tmpl.ExternalURL = &url.URL{Scheme: "http", Host: "example.com"}
+
+	groupKey := `{}:{alertname="HighErrorRate"}`
+	ctx := context.Background()
+	ctx = WithReceiverName(ctx, "webhook")
+	ctx = WithGroupKey(ctx, groupKey)
+	ctx = WithGroupLabels(ctx, model.LabelSet{"alertname": "HighErrorRate"})
+	ctx = WithNotificationReason(ctx, ReasonFirstNotification)
+
+	data := GetTemplateData(ctx, tmpl, nil, promslog.NewNopLogger())
+	require.Equal(t, groupKey, data.GroupKey)
+
+	// Templates can reference .GroupKey like other Data fields.
+	got, err := tmpl.ExecuteTextString(`{{ .GroupKey }}`, data)
+	require.NoError(t, err)
+	require.Equal(t, groupKey, got)
+
+	// Missing group key leaves GroupKey empty without failing.
+	ctxNoKey := WithReceiverName(context.Background(), "webhook")
+	ctxNoKey = WithGroupLabels(ctxNoKey, model.LabelSet{"alertname": "HighErrorRate"})
+	ctxNoKey = WithNotificationReason(ctxNoKey, ReasonFirstNotification)
+	dataNoKey := GetTemplateData(ctxNoKey, tmpl, nil, promslog.NewNopLogger())
+	require.Empty(t, dataNoKey.GroupKey)
+}
+
 func TestGetFailureReasonFromStatusCode(t *testing.T) {
 	for _, tc := range []struct {
 		statusCode int

template/template.go

@@ -485,6 +485,10 @@ type Data struct {
 	Status   string `json:"status"`
 	Alerts   Alerts `json:"alerts"`
 
+	// GroupKey is the grouping key of the alert group, matching the webhook
+	// payload field of the same name.
+	GroupKey string `json:"groupKey"`
+
 	NotificationReason string `json:"notification_reason"`
 
 	GroupLabels       KV `json:"groupLabels"`