vmalert: update the order of service labels attaching (#1922)

Service labels like `alertname` or `alertgroup` were attached
after template expanding for `labels` section. Because of this,
labels `alertname` or `alertgroup` weren't available for templating
in `labels` section of alert's definition.
This commit changes the order of labels attaching and adds a test
for verifying these labels availability.

https://github.com/VictoriaMetrics/VictoriaMetrics/issues/1921
Signed-off-by: hagen1778 <roman@victoriametrics.com>

app/vmalert/alerting.go

@@ -153,6 +153,13 @@ func (ar *AlertingRule) ExecRange(ctx context.Context, start, end time.Time) ([]
 		return nil, fmt.Errorf("`query` template isn't supported in replay mode")
 	}
 	for _, s := range series {
+		// set additional labels to identify group and rule name
+		if ar.Name != "" {
+			s.SetLabel(alertNameLabel, ar.Name)
+		}
+		if !*disableAlertGroupLabel && ar.GroupName != "" {
+			s.SetLabel(alertGroupNameLabel, ar.GroupName)
+		}
 		// extra labels could contain templates, so we expand them first
 		labels, err := expandLabels(s, qFn, ar)
 		if err != nil {
@@ -163,13 +170,6 @@ func (ar *AlertingRule) ExecRange(ctx context.Context, start, end time.Time) ([]
 			// so the hash key will be consistent on restore
 			s.SetLabel(k, v)
 		}
-		// set additional labels to identify group and rule name
-		if ar.Name != "" {
-			s.SetLabel(alertNameLabel, ar.Name)
-		}
-		if !*disableAlertGroupLabel && ar.GroupName != "" {
-			s.SetLabel(alertGroupNameLabel, ar.GroupName)
-		}
 		a, err := ar.newAlert(s, time.Time{}, qFn) // initial alert
 		if err != nil {
 			return nil, fmt.Errorf("failed to create alert: %s", err)
@@ -225,6 +225,13 @@ func (ar *AlertingRule) Exec(ctx context.Context) ([]prompbmarshal.TimeSeries, e
 	updated := make(map[uint64]struct{})
 	// update list of active alerts
 	for _, m := range qMetrics {
+		// set additional labels to identify group and rule name
+		if ar.Name != "" {
+			m.SetLabel(alertNameLabel, ar.Name)
+		}
+		if !*disableAlertGroupLabel && ar.GroupName != "" {
+			m.SetLabel(alertGroupNameLabel, ar.GroupName)
+		}
 		// extra labels could contain templates, so we expand them first
 		labels, err := expandLabels(m, qFn, ar)
 		if err != nil {
@@ -235,14 +242,6 @@ func (ar *AlertingRule) Exec(ctx context.Context) ([]prompbmarshal.TimeSeries, e
 			// so the hash key will be consistent on restore
 			m.SetLabel(k, v)
 		}
-		// set additional labels to identify group and rule name
-		// set additional labels to identify group and rule name
-		if ar.Name != "" {
-			m.SetLabel(alertNameLabel, ar.Name)
-		}
-		if !*disableAlertGroupLabel && ar.GroupName != "" {
-			m.SetLabel(alertGroupNameLabel, ar.GroupName)
-		}
 		h := hash(m)
 		if _, ok := updated[h]; ok {
 			// duplicate may be caused by extra labels

app/vmalert/alerting_test.go

@@ -715,6 +715,44 @@ func TestAlertingRule_Template(t *testing.T) {
 				},
 			},
 		},
+		{
+			&AlertingRule{
+				Name:      "ExtraTemplating",
+				GroupName: "Testing",
+				Labels: map[string]string{
+					"name":     "alert_{{ $labels.alertname }}",
+					"group":    "group_{{ $labels.alertgroup }}",
+					"instance": "{{ $labels.instance }}",
+				},
+				Annotations: map[string]string{
+					"summary":     `Alert "{{ $labels.alertname }}({{ $labels.alertgroup }})" for instance {{ $labels.instance }}`,
+					"description": `Alert "{{ $labels.name }}({{ $labels.group }})" for instance {{ $labels.instance }}`,
+				},
+				alerts: make(map[uint64]*notifier.Alert),
+			},
+			[]datasource.Metric{
+				metricWithValueAndLabels(t, 1, "instance", "foo"),
+			},
+			map[uint64]*notifier.Alert{
+				hash(metricWithLabels(t, alertNameLabel, "ExtraTemplating",
+					"name", "alert_ExtraTemplating",
+					alertGroupNameLabel, "Testing",
+					"group", "group_Testing",
+					"instance", "foo")): {
+					Labels: map[string]string{
+						alertNameLabel:      "ExtraTemplating",
+						"name":              "alert_ExtraTemplating",
+						alertGroupNameLabel: "Testing",
+						"group":             "group_Testing",
+						"instance":          "foo",
+					},
+					Annotations: map[string]string{
+						"summary":     `Alert "ExtraTemplating(Testing)" for instance foo`,
+						"description": `Alert "alert_ExtraTemplating(group_Testing)" for instance foo`,
+					},
+				},
+			},
+		},
 	}
 	fakeGroup := Group{Name: "TestRule_Exec"}
 	for _, tc := range testCases {