Reduce coredns replicas from 2 to 1

This is an easy way to improve overhead, and users can always scale this back up if they need to.

pkg/addons/kubectl.go

@@ -32,7 +32,7 @@ func kubectlCommand(cc *config.ClusterConfig, files []string, enable bool) *exec
 		v = cc.KubernetesConfig.KubernetesVersion
 	}
 
-	kubectlBinary := kubectlBinaryPath(v)
+	kubectlBinary := KubectlBinaryPath(v)
 
 	kubectlAction := "apply"
 	if !enable {
@@ -47,6 +47,7 @@ func kubectlCommand(cc *config.ClusterConfig, files []string, enable bool) *exec
 	return exec.Command("sudo", args...)
 }
 
-func kubectlBinaryPath(version string) string {
+// KubectlBinaryPath returns the path to kubectl on the node
+func KubectlBinaryPath(version string) string {
 	return path.Join(vmpath.GuestPersistentDir, "binaries", version, "kubectl")
 }

pkg/minikube/node/start.go

@@ -146,6 +146,12 @@ func Start(starter Starter, apiServer bool) (*kubeconfig.Settings, error) {
 		go addons.Start(&wg, starter.Cfg, starter.ExistingAddons, config.AddonList)
 	}
 
+	wg.Add(1)
+	go func() {
+		rescaleCoreDNS(starter.Cfg, starter.Runner)
+		wg.Done()
+	}()
+
 	if apiServer {
 		// special ops for none , like change minikube directory.
 		// multinode super doesn't work on the none driver
@@ -507,3 +513,15 @@ func prepareNone() {
 		exit.WithCodeT(exit.Permissions, "Failed to change permissions for {{.minikube_dir_path}}: {{.error}}", out.V{"minikube_dir_path": localpath.MiniPath(), "error": err})
 	}
 }
+
+// rescaleCoreDNS attempts to reduce coredns replicas from 2 to 1 to improve CPU overhead
+// no worries if this doesn't work
+func rescaleCoreDNS(cc *config.ClusterConfig, runner command.Runner) {
+	kubectl := addons.KubectlBinaryPath(cc.KubernetesConfig.KubernetesVersion)
+	cmd := exec.Command("sudo", "KUBECONFIG=/var/lib/minikube/kubeconfig", kubectl, "scale", "deployment", "--replicas=1", "coredns", "-n=kube-system")
+	if _, err := runner.RunCmd(cmd); err != nil {
+		glog.Infof("unable to scale coredns replicas to 1: %v", err)
+	} else {
+		glog.Infof("successfully scaled coredns replicas to 1")
+	}
+}