kube-controller-manager: enable WatchListClient

cmd/kube-controller-manager/app/options/options.go

@@ -25,6 +25,7 @@ import (
 	utilerrors "k8s.io/apimachinery/pkg/util/errors"
 	apiserveroptions "k8s.io/apiserver/pkg/server/options"
 	utilfeature "k8s.io/apiserver/pkg/util/feature"
+	clientgofeaturegate "k8s.io/client-go/features"
 	clientset "k8s.io/client-go/kubernetes"
 	clientgokubescheme "k8s.io/client-go/kubernetes/scheme"
 	restclient "k8s.io/client-go/rest"
@@ -33,10 +34,12 @@ import (
 	cpnames "k8s.io/cloud-provider/names"
 	cpoptions "k8s.io/cloud-provider/options"
 	cliflag "k8s.io/component-base/cli/flag"
+	"k8s.io/component-base/featuregate"
 	"k8s.io/component-base/logs"
 	logsapi "k8s.io/component-base/logs/api/v1"
 	"k8s.io/component-base/metrics"
 	cmoptions "k8s.io/controller-manager/options"
+	"k8s.io/klog/v2"
 	kubectrlmgrconfigv1alpha1 "k8s.io/kube-controller-manager/config/v1alpha1"
 	kubecontrollerconfig "k8s.io/kubernetes/cmd/kube-controller-manager/app/config"
 	"k8s.io/kubernetes/cmd/kube-controller-manager/names"
@@ -273,6 +276,16 @@ func (s *KubeControllerManagerOptions) Flags(allControllers []string, disabledBy
 	fs := fss.FlagSet("misc")
 	fs.StringVar(&s.Master, "master", s.Master, "The address of the Kubernetes API server (overrides any value in kubeconfig).")
 	fs.StringVar(&s.Generic.ClientConnection.Kubeconfig, "kubeconfig", s.Generic.ClientConnection.Kubeconfig, "Path to kubeconfig file with authorization and master location information (the master location can be overridden by the master flag).")
+
+	if !utilfeature.DefaultFeatureGate.Enabled(featuregate.Feature(clientgofeaturegate.WatchListClient)) {
+		if err := utilfeature.DefaultMutableFeatureGate.OverrideDefault(featuregate.Feature(clientgofeaturegate.WatchListClient), true); err != nil {
+			// it turns out that there are some integration tests that start multiple control plane components which
+			// share global DefaultFeatureGate/DefaultMutableFeatureGate variables.
+			// in those cases, the above call will fail (FG already registered and cannot be overridden), and the error will be logged.
+			klog.Errorf("unable to set %s feature gate, err: %v", clientgofeaturegate.WatchListClient, err)
+		}
+	}
+
 	utilfeature.DefaultMutableFeatureGate.AddFlag(fss.FlagSet("generic"))
 
 	return fss

cmd/kube-controller-manager/app/options/options_test.go

@@ -1353,8 +1353,8 @@ func TestWatchListClientFlagChange(t *testing.T) {
 
 func assertWatchListClientFeatureDefaultValue(t *testing.T) {
 	watchListClientDefaultValue := clientgofeaturegate.FeatureGates().Enabled(clientgofeaturegate.WatchListClient)
-	if watchListClientDefaultValue {
-		t.Fatalf("expected %q feature gate to be disabled for KCM", clientgofeaturegate.WatchListClient)
+	if !watchListClientDefaultValue {
+		t.Fatalf("expected %q feature gate to be enabled for KCM", clientgofeaturegate.WatchListClient)
 	}
 }
 
@@ -1365,7 +1365,7 @@ func assertWatchListCommandLineDefaultValue(t *testing.T, fs *pflag.FlagSet) {
 		t.Fatalf("didn't find %q flag", fgFlagName)
 	}
 
-	expectedWatchListClientString := "WatchListClient=true|false (BETA - default=false)"
+	expectedWatchListClientString := "WatchListClient=true|false (BETA - default=true)"
 	if !strings.Contains(fg.Usage, expectedWatchListClientString) {
 		t.Fatalf("%q flag doesn't contain the expected usage for %v feature gate.\nExpected = %v\nUsage = %v", fgFlagName, clientgofeaturegate.WatchListClient, expectedWatchListClientString, fg.Usage)
 	}