Fix TidbMonitor ClusterRef missing error in prometheus rule (pingcap#…

…2746) (pingcap#2766)

Signed-off-by: ti-srebot <ti-srebot@pingcap.com>

Co-authored-by: Song Gao <disxiaofei@163.com>

pkg/monitor/monitor/monitor_manager.go

@@ -87,14 +87,14 @@ func NewMonitorManager(
 }
 
 func (mm *MonitorManager) SyncMonitor(monitor *v1alpha1.TidbMonitor) error {
-
 	if monitor.DeletionTimestamp != nil {
 		return nil
 	}
 	if monitor.Spec.Clusters == nil || len(monitor.Spec.Clusters) < 1 {
 		err := fmt.Errorf("tm[%s/%s] does not configure the target tidbcluster", monitor.Namespace, monitor.Name)
 		return err
 	}
+	defaultTidbMonitor(monitor)
 	tcRef := monitor.Spec.Clusters[0]
 	if len(tcRef.Namespace) < 1 {
 		tcRef.Namespace = monitor.Namespace

pkg/monitor/monitor/util.go

@@ -856,3 +856,12 @@ func prometheusName(monitor *v1alpha1.TidbMonitor) string {
 func grafanaName(monitor *v1alpha1.TidbMonitor) string {
 	return fmt.Sprintf("%s-grafana", monitor.Name)
 }
+
+func defaultTidbMonitor(monitor *v1alpha1.TidbMonitor) {
+	for id, tcRef := range monitor.Spec.Clusters {
+		if len(tcRef.Namespace) < 1 {
+			tcRef.Namespace = monitor.Namespace
+		}
+		monitor.Spec.Clusters[id] = tcRef
+	}
+}