Enable HorizontalPodAutoscalerUseRESTClients option

cluster/gce/gci/configure-helper.sh

@@ -1602,6 +1602,10 @@ function start-kube-controller-manager {
   if [[ -n "${CLUSTER_SIGNING_DURATION:-}" ]]; then
     params+=" --experimental-cluster-signing-duration=$CLUSTER_SIGNING_DURATION"
   fi
+  # disable using HPA metrics REST clients if metrics-server isn't enabled
+  if [[ "${ENABLE_METRICS_SERVER:-}" != "true" ]]; then
+    params+=" --horizontal-pod-autoscaler-use-rest-clients=false"
+  fi
 
   local -r kube_rc_docker_tag=$(cat /home/kubernetes/kube-docker-files/kube-controller-manager.docker_tag)
   local container_env=""

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

@@ -115,7 +115,7 @@ func NewCMServer() *CMServer {
 			ClusterSigningDuration:                metav1.Duration{Duration: helpers.OneYear},
 			ReconcilerSyncLoopPeriod:              metav1.Duration{Duration: 60 * time.Second},
 			EnableTaintManager:                    true,
-			HorizontalPodAutoscalerUseRESTClients: false,
+			HorizontalPodAutoscalerUseRESTClients: true,
 		},
 	}
 	s.LeaderElection.LeaderElect = true

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

@@ -192,15 +192,16 @@ func TestAddFlags(t *testing.T) {
 				{Group: "apiregistration.k8s.io", Resource: "apiservices"},
 				{Group: "apiextensions.k8s.io", Resource: "customresourcedefinitions"},
 			},
-			NodeEvictionRate:                  0.2,
-			SecondaryNodeEvictionRate:         0.05,
-			LargeClusterSizeThreshold:         100,
-			UnhealthyZoneThreshold:            0.6,
-			DisableAttachDetachReconcilerSync: true,
-			ReconcilerSyncLoopPeriod:          metav1.Duration{Duration: 30 * time.Second},
-			Controllers:                       []string{"foo", "bar"},
-			EnableTaintManager:                false,
-			UseServiceAccountCredentials:      true,
+			NodeEvictionRate:                      0.2,
+			SecondaryNodeEvictionRate:             0.05,
+			LargeClusterSizeThreshold:             100,
+			UnhealthyZoneThreshold:                0.6,
+			DisableAttachDetachReconcilerSync:     true,
+			ReconcilerSyncLoopPeriod:              metav1.Duration{Duration: 30 * time.Second},
+			Controllers:                           []string{"foo", "bar"},
+			EnableTaintManager:                    false,
+			HorizontalPodAutoscalerUseRESTClients: true,
+			UseServiceAccountCredentials:          true,
 		},
 		Kubeconfig: "/kubeconfig",
 		Master:     "192.168.4.20",