Merge pull request kubernetes#121878 from aojea/default_servicecidr_controller_startup

improve default_servicecidr_controller startup

Author: k8s-ci-robot

pkg/controlplane/controller/defaultservicecidr/default_servicecidr_controller.go

@@ -82,8 +82,6 @@ func NewController(
 	c.eventBroadcaster = broadcaster
 	c.eventRecorder = recorder
 
-	c.readyCh = make(chan struct{})
-
 	return c
 }
 
@@ -99,8 +97,6 @@ type Controller struct {
 	serviceCIDRLister   networkingv1alpha1listers.ServiceCIDRLister
 	serviceCIDRsSynced  cache.InformerSynced
 
-	readyCh chan struct{} // channel to block until the default ServiceCIDR exists
-
 	interval time.Duration
 }
 
@@ -120,28 +116,40 @@ func (c *Controller) Start(stopCh <-chan struct{}) {
 		return
 	}
 
-	go wait.Until(c.sync, c.interval, stopCh)
+	// derive a context from the stopCh so we can cancel the poll loop
+	ctx := wait.ContextForChannel(stopCh)
+	// wait until first successfully sync
+	// this blocks apiserver startup so poll with a short interval
+	err := wait.PollUntilContextCancel(ctx, 100*time.Millisecond, true, func(ctx context.Context) (bool, error) {
+		syncErr := c.sync()
+		return syncErr == nil, nil
+	})
+	if err != nil {
+		klog.Infof("error initializing the default ServiceCIDR: %v", err)
 
-	select {
-	case <-stopCh:
-	case <-c.readyCh:
 	}
+
+	// run the sync loop in the background with the defined interval
+	go wait.Until(func() {
+		err := c.sync()
+		if err != nil {
+			klog.Infof("error trying to sync the default ServiceCIDR: %v", err)
+		}
+	}, c.interval, stopCh)
 }
 
-func (c *Controller) sync() {
+func (c *Controller) sync() error {
 	// check if the default ServiceCIDR already exist
 	serviceCIDR, err := c.serviceCIDRLister.Get(DefaultServiceCIDRName)
 	// if exists
 	if err == nil {
-		c.setReady()
 		c.syncStatus(serviceCIDR)
-		return
+		return nil
 	}
 
 	// unknown error
 	if !apierrors.IsNotFound(err) {
-		klog.Infof("error trying to obtain the default ServiceCIDR: %v", err)
-		return
+		return err
 	}
 
 	// default ServiceCIDR does not exist
@@ -156,21 +164,11 @@ func (c *Controller) sync() {
 	}
 	serviceCIDR, err = c.client.NetworkingV1alpha1().ServiceCIDRs().Create(context.Background(), serviceCIDR, metav1.CreateOptions{})
 	if err != nil && !apierrors.IsAlreadyExists(err) {
-		klog.Infof("error creating default ServiceCIDR: %v", err)
 		c.eventRecorder.Eventf(serviceCIDR, v1.EventTypeWarning, "KubernetesDefaultServiceCIDRError", "The default ServiceCIDR can not be created")
-		return
+		return err
 	}
-
-	c.setReady()
 	c.syncStatus(serviceCIDR)
-}
-
-func (c *Controller) setReady() {
-	select {
-	case <-c.readyCh:
-	default:
-		close(c.readyCh)
-	}
+	return nil
 }
 
 func (c *Controller) syncStatus(serviceCIDR *networkingapiv1alpha1.ServiceCIDR) {

pkg/controlplane/controller/defaultservicecidr/default_servicecidr_controller_test.go

@@ -56,7 +56,6 @@ func newController(t *testing.T, objects []*networkingapiv1alpha1.ServiceCIDR) (
 		eventRecorder:      record.NewFakeRecorder(100),
 		serviceCIDRLister:  serviceCIDRInformer.Lister(),
 		serviceCIDRsSynced: func() bool { return true },
-		readyCh:            make(chan struct{}),
 	}
 
 	return client, c