Fix crash on kube manager's service-lb-controller after v1.31.0.

Co-authored-by: Antonio Ojea <antonio.ojea.garcia@gmail.com>

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

@@ -219,3 +219,29 @@ func TestTaintEvictionControllerGating(t *testing.T) {
 		})
 	}
 }
+
+func TestNoCloudProviderControllerStarted(t *testing.T) {
+	_, ctx := ktesting.NewTestContext(t)
+	ctx, cancel := context.WithCancel(ctx)
+	defer cancel()
+
+	controllerCtx := ControllerContext{
+		Cloud:    nil,
+		LoopMode: IncludeCloudLoops,
+	}
+	controllerCtx.ComponentConfig.Generic.Controllers = []string{"*"}
+	for _, controller := range NewControllerDescriptors() {
+		if !controller.IsCloudProviderController() {
+			continue
+		}
+
+		controllerName := controller.Name()
+		checker, err := StartController(ctx, controllerCtx, controller, nil)
+		if err != nil {
+			t.Errorf("Error starting controller %q: %v", controllerName, err)
+		}
+		if checker != nil {
+			t.Errorf("Controller %q should not be started", controllerName)
+		}
+	}
+}

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

@@ -92,6 +92,12 @@ func newServiceLBControllerDescriptor() *ControllerDescriptor {
 }
 
 func startServiceLBController(ctx context.Context, controllerContext ControllerContext, controllerName string) (controller.Interface, bool, error) {
+	logger := klog.FromContext(ctx)
+	if controllerContext.Cloud == nil {
+		logger.Info("Warning: service-controller is set, but no cloud provider specified. Will not configure service controller.")
+		return nil, false, nil
+	}
+
 	serviceController, err := servicecontroller.New(
 		controllerContext.Cloud,
 		controllerContext.ClientBuilder.ClientOrDie("service-controller"),
@@ -102,7 +108,7 @@ func startServiceLBController(ctx context.Context, controllerContext ControllerC
 	)
 	if err != nil {
 		// This error shouldn't fail. It lives like this as a legacy.
-		klog.FromContext(ctx).Error(err, "Failed to start service controller")
+		logger.Error(err, "Failed to start service controller.")
 		return nil, false, nil
 	}
 	go serviceController.Run(ctx, int(controllerContext.ComponentConfig.ServiceController.ConcurrentServiceSyncs), controllerContext.ControllerManagerMetrics)
@@ -261,6 +267,11 @@ func newCloudNodeLifecycleControllerDescriptor() *ControllerDescriptor {
 
 func startCloudNodeLifecycleController(ctx context.Context, controllerContext ControllerContext, controllerName string) (controller.Interface, bool, error) {
 	logger := klog.FromContext(ctx)
+	if controllerContext.Cloud == nil {
+		logger.Info("Warning: node-controller is set, but no cloud provider specified. Will not configure node lifecyle controller.")
+		return nil, false, nil
+	}
+
 	cloudNodeLifecycleController, err := cloudnodelifecyclecontroller.NewCloudNodeLifecycleController(
 		controllerContext.InformerFactory.Core().V1().Nodes(),
 		// cloud node lifecycle controller uses existing cluster role from node-controller

staging/src/k8s.io/cloud-provider/controllers/service/controller.go

@@ -110,6 +110,7 @@ func New(
 	featureGate featuregate.FeatureGate,
 ) (*Controller, error) {
 	registerMetrics()
+
 	s := &Controller{
 		cloud:            cloud,
 		kubeClient:       kubeClient,
@@ -128,6 +129,10 @@ func New(
 		lastSyncedNodes: make(map[string][]*v1.Node),
 	}
 
+	if err := s.init(); err != nil {
+		return nil, err
+	}
+
 	serviceInformer.Informer().AddEventHandlerWithResyncPeriod(
 		cache.ResourceEventHandlerFuncs{
 			AddFunc: func(cur interface{}) {
@@ -182,10 +187,6 @@ func New(
 		nodeSyncPeriod,
 	)
 
-	if err := s.init(); err != nil {
-		return nil, err
-	}
-
 	return s, nil
 }