Docker driver: force docker to use systemd as cgroup manager

Since minikube is running systemd, kubeadm expects kubeadm to be the cgroup manager. If docker is using a different cgroup manager like cgroupfs, this can cause unstable resource allocation. We were seeing this in Cloud Shell, and forcing docker to use systemd resolved the issue.

pkg/minikube/cruntime/containerd.go

@@ -429,3 +429,8 @@ func addRepoTagToImageName(imgName string) string {
 	} // else it already has repo name dont add anything
 	return imgName
 }
+
+// TODO: Enable for containerd
+func (r *Containerd) ForceSystemdCgroupManager() error {
+	return nil
+}

pkg/minikube/cruntime/crio.go

@@ -229,3 +229,8 @@ func (r *CRIO) Preload(cfg config.KubernetesConfig) error {
 	}
 	return fmt.Errorf("not yet implemented for %s", r.Name())
 }
+
+// ForceSystemdCgroupManager does nothing since CRIO already uses systemd
+func (r *CRIO) ForceSystemdCgroupManager() error {
+	return nil
+}

pkg/minikube/cruntime/cruntime.go

@@ -104,6 +104,8 @@ type Manager interface {
 	SystemLogCmd(int) string
 	// Preload preloads the container runtime with k8s images
 	Preload(config.KubernetesConfig) error
+	// ForceSystemdCgroupManager forces the runtime to use systemd as cgroup manager
+	ForceSystemdCgroupManager() error
 }
 
 // Config is runtime configuration

pkg/minikube/cruntime/docker.go

@@ -365,6 +365,25 @@ func dockerImagesPreloaded(runner command.Runner, images []string) bool {
 	return true
 }
 
+// ForceSystemdCgroupManager forces docker to use systemd as cgroup manager, as recommended in k8s docs:
+// https://kubernetes.io/docs/setup/production-environment/container-runtimes/#docker
+func (r *Docker) ForceSystemdCgroupManager() error {
+	daemonConfig := `{
+"exec-opts": ["native.cgroupdriver=systemd"],
+"log-driver": "json-file",
+"log-opts": {
+	"max-size": "100m"
+},
+"storage-driver": "overlay2"
+}
+`
+	ma := assets.NewMemoryAsset([]byte(daemonConfig), "/etc/docker", "daemon.json", "0644")
+	if err := r.Runner.Copy(ma); err != nil {
+		return errors.Wrap(err, "copying daemon config")
+	}
+	return r.Restart()
+}
+
 func dockerBoundToContainerd(runner command.Runner) bool {
 	// NOTE: assumes systemd
 	rr, err := runner.RunCmd(exec.Command("sudo", "systemctl", "cat", "docker.service"))

pkg/minikube/node/start.go

@@ -99,6 +99,7 @@ func Start(starter Starter, apiServer bool) (*kubeconfig.Settings, error) {
 
 		// setup kubeadm (must come after setupKubeconfig)
 		bs = setupKubeAdm(starter.MachineAPI, *starter.Cfg, *starter.Node, starter.Runner)
+
 		err = bs.StartCluster(*starter.Cfg)
 
 		if err != nil {
@@ -261,6 +262,12 @@ func configureRuntimes(runner cruntime.CommandRunner, cc config.ClusterConfig, k
 		exit.WithError("Failed to enable container runtime", err)
 	}
 
+	if driver.IsKIC(cc.Driver) {
+		if err := cr.ForceSystemdCgroupManager(); err != nil {
+			glog.Warningf("Failed to force %s to use systemd as cgroup manager (this might be ok): %v", cr.Name(), err)
+		}
+	}
+
 	return cr
 }