cloud-controller-manager get /healthz instead of calling restclient.ServerAPIVersions to wait for apiserver being healthy

cmd/cloud-controller-manager/app/controllermanager.go

@@ -260,15 +260,9 @@ func startControllers(c *cloudcontrollerconfig.CompletedConfig, kubeconfig *rest
 
 	// If apiserver is not running we should wait for some time and fail only then. This is particularly
 	// important when we start apiserver and controller manager at the same time.
-	err = wait.PollImmediate(time.Second, 10*time.Second, func() (bool, error) {
-		if _, err = restclient.ServerAPIVersions(kubeconfig); err == nil {
-			return true, nil
-		}
-		glog.Errorf("Failed to get api versions from server: %v", err)
-		return false, nil
-	})
+	err = genericcontrollermanager.WaitForAPIServer(versionedClient, 10*time.Second)
 	if err != nil {
-		glog.Fatalf("Failed to get api versions from server: %v", err)
+		glog.Fatalf("Failed to wait for apiserver being healthy: %v", err)
 	}
 
 	sharedInformers.Start(stop)

cmd/controller-manager/app/helper.go

@@ -0,0 +1,55 @@
+/*
+Copyright 2018 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package app
+
+import (
+	"fmt"
+	"net/http"
+	"time"
+
+	"github.com/golang/glog"
+	"k8s.io/apimachinery/pkg/util/wait"
+	clientset "k8s.io/client-go/kubernetes"
+)
+
+// WaitForAPIServer waits for the API Server's /healthz endpoint to report "ok" with timeout.
+func WaitForAPIServer(client clientset.Interface, timeout time.Duration) error {
+	var lastErr error
+
+	err := wait.PollImmediate(time.Second, timeout, func() (bool, error) {
+		healthStatus := 0
+		result := client.Discovery().RESTClient().Get().AbsPath("/healthz").Do().StatusCode(&healthStatus)
+		if result.Error() != nil {
+			lastErr = fmt.Errorf("failed to get apiserver /healthz status: %v", result.Error())
+			return false, nil
+		}
+		if healthStatus != http.StatusOK {
+			content, _ := result.Raw()
+			lastErr = fmt.Errorf("APIServer isn't healthy: %v", string(content))
+			glog.Warningf("APIServer isn't healthy yet: %v. Waiting a little while.", string(content))
+			return false, nil
+		}
+
+		return true, nil
+	})
+
+	if err != nil {
+		return fmt.Errorf("%v: %v", err, lastErr)
+	}
+
+	return nil
+}

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

@@ -24,7 +24,6 @@ import (
 	"fmt"
 	"io/ioutil"
 	"math/rand"
-	"net/http"
 	"os"
 	"time"
 
@@ -36,7 +35,6 @@ import (
 	"k8s.io/apimachinery/pkg/util/sets"
 	"k8s.io/apimachinery/pkg/util/uuid"
 	"k8s.io/apimachinery/pkg/util/wait"
-	"k8s.io/client-go/discovery"
 	"k8s.io/client-go/informers"
 	restclient "k8s.io/client-go/rest"
 	"k8s.io/client-go/tools/leaderelection"
@@ -350,34 +348,8 @@ func NewControllerInitializers(loopMode ControllerLoopMode) map[string]InitFunc
 //  users don't have to restart their controller manager if they change the apiserver.
 // Until we get there, the structure here needs to be exposed for the construction of a proper ControllerContext.
 func GetAvailableResources(clientBuilder controller.ControllerClientBuilder) (map[schema.GroupVersionResource]bool, error) {
-	var discoveryClient discovery.DiscoveryInterface
-
-	var healthzContent string
-	// If apiserver is not running we should wait for some time and fail only then. This is particularly
-	// important when we start apiserver and controller manager at the same time.
-	err := wait.PollImmediate(time.Second, 10*time.Second, func() (bool, error) {
-		client, err := clientBuilder.Client("controller-discovery")
-		if err != nil {
-			glog.Errorf("Failed to get api versions from server: %v", err)
-			return false, nil
-		}
-
-		healthStatus := 0
-		resp := client.Discovery().RESTClient().Get().AbsPath("/healthz").Do().StatusCode(&healthStatus)
-		if healthStatus != http.StatusOK {
-			glog.Errorf("Server isn't healthy yet.  Waiting a little while.")
-			return false, nil
-		}
-		content, _ := resp.Raw()
-		healthzContent = string(content)
-
-		discoveryClient = client.Discovery()
-		return true, nil
-	})
-	if err != nil {
-		return nil, fmt.Errorf("failed to get api versions from server: %v: %v", healthzContent, err)
-	}
-
+	client := clientBuilder.ClientOrDie("controller-discovery")
+	discoveryClient := client.Discovery()
 	resourceMap, err := discoveryClient.ServerResources()
 	if err != nil {
 		utilruntime.HandleError(fmt.Errorf("unable to get all supported resources from server: %v", err))
@@ -407,6 +379,12 @@ func CreateControllerContext(s *config.CompletedConfig, rootClientBuilder, clien
 	versionedClient := rootClientBuilder.ClientOrDie("shared-informers")
 	sharedInformers := informers.NewSharedInformerFactory(versionedClient, ResyncPeriod(s)())
 
+	// If apiserver is not running we should wait for some time and fail only then. This is particularly
+	// important when we start apiserver and controller manager at the same time.
+	if err := genericcontrollerconfig.WaitForAPIServer(versionedClient, 10*time.Second); err != nil {
+		return ControllerContext{}, fmt.Errorf("failed to wait for apiserver being healthy: %v", err)
+	}
+
 	availableResources, err := GetAvailableResources(rootClientBuilder)
 	if err != nil {
 		return ControllerContext{}, err