[kube-controller-manager] Lower timeout for leaderelection resourcelock

Migrate how resource lock and leader election config is generated to new way, hidding kubeClient. This also halfs kubeClient timeout, making it an useful value.

If timeout is equal to RenewDeadline and we hit client timeout on request, there will be no retry, as RenewDeadline part will cancel the context and lose leader election. So setting a timeout to value at least equal to RenewDeadline is pointless.

Setting it as half of RenewDeadline is a heuristic to resolve this missing retry problem without adding additional parameter.

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

@@ -441,18 +441,12 @@ func (s KubeControllerManagerOptions) Config(allControllers []string, disabledBy
 		return nil, err
 	}
 
-	// shallow copy, do not modify the kubeconfig.Timeout.
-	config := *kubeconfig
-	config.Timeout = s.Generic.LeaderElection.RenewDeadline.Duration
-	leaderElectionClient := clientset.NewForConfigOrDie(restclient.AddUserAgent(&config, "leader-election"))
-
 	eventRecorder := createRecorder(client, KubeControllerManagerUserAgent)
 
 	c := &kubecontrollerconfig.Config{
-		Client:               client,
-		Kubeconfig:           kubeconfig,
-		EventRecorder:        eventRecorder,
-		LeaderElectionClient: leaderElectionClient,
+		Client:        client,
+		Kubeconfig:    kubeconfig,
+		EventRecorder: eventRecorder,
 	}
 	if err := s.ApplyTo(c); err != nil {
 		return nil, err