cluster up: set docker cgroup driver on kubelet config

On kubelet versions that support the --enforce-node-allocatable
argument, set the cgroup-driver flag to the one reported by docker.
If the cgroup-driver is not systemd, also specify
--enforce-node-allocatable and --cgroups-per-qos arguments.

Author: csrwng

pkg/bootstrap/docker/dockerhelper/helper.go

@@ -77,6 +77,14 @@ func (h *Helper) dockerInfo() (*dockertypes.Info, error) {
 	return h.info, nil
 }
 
+func (h *Helper) CgroupDriver() (string, error) {
+	info, err := h.dockerInfo()
+	if err != nil {
+		return "", err
+	}
+	return info.CgroupDriver, nil
+}
+
 // HasInsecureRegistryArg checks whether the docker daemon is configured with
 // the appropriate insecure registry argument
 func (h *Helper) HasInsecureRegistryArg() (bool, error) {

pkg/bootstrap/docker/openshift/helper.go

@@ -116,10 +116,10 @@ type StartOptions struct {
 }
 
 // NewHelper creates a new OpenShift helper
-func NewHelper(client *docker.Client, hostHelper *host.HostHelper, image, containerName, publicHostname, routingSuffix string) *Helper {
+func NewHelper(client *docker.Client, dockerHelper *dockerhelper.Helper, hostHelper *host.HostHelper, image, containerName, publicHostname, routingSuffix string) *Helper {
 	return &Helper{
 		client:        client,
-		dockerHelper:  dockerhelper.NewHelper(client, nil),
+		dockerHelper:  dockerHelper,
 		execHelper:    dockerexec.NewExecHelper(client, containerName),
 		hostHelper:    hostHelper,
 		runHelper:     run.NewRunHelper(client),
@@ -730,6 +730,23 @@ func (h *Helper) updateConfig(configDir string, opt *StartOptions) error {
 		nodeCfg.DNSIP = ""
 	}
 	nodeCfg.DNSBindAddress = ""
+
+	if h.supportsEnforceNodeAllocatableArgument() {
+		// Set the cgroup driver from the current docker
+		cgroupDriver, err := h.dockerHelper.CgroupDriver()
+		if err != nil {
+			return err
+		}
+		if nodeCfg.KubeletArguments == nil {
+			nodeCfg.KubeletArguments = configapi.ExtendedArguments{}
+		}
+		nodeCfg.KubeletArguments["cgroup-driver"] = []string{cgroupDriver}
+		if cgroupDriver != "systemd" {
+			nodeCfg.KubeletArguments["enforce-node-allocatable"] = []string{""}
+			nodeCfg.KubeletArguments["cgroups-per-qos"] = []string{"false"}
+		}
+	}
+
 	cfgBytes, err = configapilatest.WriteYAML(nodeCfg)
 	if err != nil {
 		return err
@@ -784,3 +801,25 @@ func getUsedPorts(data string) map[int]struct{} {
 	glog.V(2).Infof("Used ports in container: %#v", ports)
 	return ports
 }
+
+func (h *Helper) supportsEnforceNodeAllocatableArgument() bool {
+	script := `#!/bin/bash
+
+# Exit with an error
+set -e
+
+# Ensure we have a link to the openshift binary named kubelet
+if [[ ! -f /usr/bin/kubelet ]]; then
+   ln -s /usr/bin/openshift /usr/bin/kubelet
+fi
+
+kubelet --help | grep -- "--enforce-node-allocatable"
+`
+	rc, err := h.runHelper.New().Image(h.image).
+		DiscardContainer().
+		Entrypoint("/bin/bash").
+		Command("-c", script).
+		Run()
+
+	return rc == 0 && err == nil
+}

pkg/bootstrap/docker/up.go

@@ -1071,7 +1071,7 @@ func (c *ClientStartConfig) Clients() (*client.Client, kclientset.Interface, err
 // OpenShiftHelper returns a helper object to work with OpenShift on the server
 func (c *CommonStartConfig) OpenShiftHelper() *openshift.Helper {
 	if c.openshiftHelper == nil {
-		c.openshiftHelper = openshift.NewHelper(c.dockerClient, c.HostHelper(), c.openshiftImage(), openshift.OpenShiftContainer, c.PublicHostname, c.RoutingSuffix)
+		c.openshiftHelper = openshift.NewHelper(c.dockerClient, c.DockerHelper(), c.HostHelper(), c.openshiftImage(), openshift.OpenShiftContainer, c.PublicHostname, c.RoutingSuffix)
 	}
 	return c.openshiftHelper
 }