Feat: skip ocm cluster watch when not installed

Signed-off-by: Yin Da <[email protected]>

pkg/util/cluster/cluster.go

@@ -2,8 +2,11 @@ package cluster
 
 import (
 	"context"
+	"fmt"
+
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/labels"
+	"k8s.io/apimachinery/pkg/runtime/schema"
 	ocmclient "open-cluster-management.io/api/client/cluster/clientset/versioned"
 	clusterv1Lister "open-cluster-management.io/api/client/cluster/listers/cluster/v1"
 	clusterv1 "open-cluster-management.io/api/cluster/v1"
@@ -63,3 +66,21 @@ func (c *cacheOCMClusterControl) Get(ctx context.Context, name string) (*cluster
 func (c *cacheOCMClusterControl) List(ctx context.Context) ([]*clusterv1.ManagedCluster, error) {
 	return c.clusterLister.List(labels.Everything())
 }
+
+// IsOCMManagedClusterInstalled check if managed cluster is installed in the cluster
+func IsOCMManagedClusterInstalled(ocmClient ocmclient.Interface) (bool, error) {
+	_, resources, err := ocmClient.Discovery().ServerGroupsAndResources()
+	if err != nil {
+		return false, fmt.Errorf("unable to get api-resources: %w", err)
+	}
+	for _, resource := range resources {
+		if gv, _ := schema.ParseGroupVersion(resource.GroupVersion); gv.Group == clusterv1.GroupName {
+			for _, rsc := range resource.APIResources {
+				if rsc.Kind == "ManagedCluster" {
+					return true, nil
+				}
+			}
+		}
+	}
+	return false, nil
+}

pkg/util/singleton/loopback.go

@@ -3,6 +3,7 @@ package singleton
 import (
 	"time"
 
+	"k8s.io/klog/v2"
 	controllerruntimeconfig "sigs.k8s.io/controller-runtime/pkg/client/config"
 
 	"github.com/oam-dev/cluster-gateway/pkg/config"
@@ -77,7 +78,12 @@ func InitLoopbackClient(ctx server.PostStartHookContext) error {
 	}
 
 	if utilfeature.DefaultMutableFeatureGate.Enabled(featuregates.OCMClusterCache) {
-		if err := setOCMClusterInformer(ocmClient, ctx.StopCh); err != nil {
+		installed, err := clusterutil.IsOCMManagedClusterInstalled(ocmClient)
+		if err != nil {
+			klog.Error(err)
+		} else if !installed {
+			klog.Infof("OCM ManagedCluster CRD not installed, skip bootstrapping informer for OCM ManagedCluster")
+		} else if err := setOCMClusterInformer(ocmClient, ctx.StopCh); err != nil {
 			return err
 		}
 		clusterControl = clusterutil.NewCacheOCMClusterControl(clusterLister)