Merge pull request #25907 from ncdc/check-docker-pidfile

Automatic merge from submit-queue Fix detection of docker cgroup on RHEL Check docker's pid file, then fallback to pidof when trying to determine the pid for docker. The latest docker RPM for RHEL changes /usr/bin/docker from an executable to a shell script (to support /usr/bin/docker-current and /usr/bin/docker-latest). The pidof check for docker fails in this case, so we check /var/run/docker.pid first (the default location), and fallback to pidof if that fails. @kubernetes/sig-node @kubernetes/rh-cluster-infra
kubernetes · May 21, 2016 · 5d8e797 · 5d8e797
2 parents 009ae74 + 6744a74
commit 5d8e797
Showing 1 changed file with 40 additions and 5 deletions.
diff --git a/pkg/kubelet/cm/container_manager_linux.go b/pkg/kubelet/cm/container_manager_linux.go
@@ -20,6 +20,7 @@ package cm
 
 import (
 	"fmt"
+	"io/ioutil"
 	"os"
 	"os/exec"
 	"path"
@@ -39,6 +40,7 @@ import (
 	utilerrors "k8s.io/kubernetes/pkg/util/errors"
 	"k8s.io/kubernetes/pkg/util/mount"
 	"k8s.io/kubernetes/pkg/util/oom"
+	"k8s.io/kubernetes/pkg/util/runtime"
 	"k8s.io/kubernetes/pkg/util/sets"
 	utilsysctl "k8s.io/kubernetes/pkg/util/sysctl"
 	"k8s.io/kubernetes/pkg/util/wait"
@@ -51,6 +53,9 @@ const (
 	DockerMemoryLimitThresholdPercent = 70
 	// The minimum memory limit allocated to docker container: 150Mi
 	MinDockerMemoryLimit = 150 * 1024 * 1024
+
+	dockerProcessName = "docker"
+	dockerPidFile     = "/var/run/docker.pid"
 )
 
 // A non-user container tracked by the Kubelet.
@@ -262,11 +267,12 @@ func (cm *containerManagerImpl) setupNode() error {
 			systemContainers = append(systemContainers, cont)
 		} else {
 			cm.periodicTasks = append(cm.periodicTasks, func() {
-				cont, err := getContainerNameForProcess("docker")
+				cont, err := getContainerNameForProcess(dockerProcessName, dockerPidFile)
 				if err != nil {
 					glog.Error(err)
 					return
 				}
+				glog.V(2).Infof("Discovered runtime cgroups name: %s", cont)
 				cm.Lock()
 				defer cm.Unlock()
 				cm.RuntimeCgroupsName = cont
@@ -324,8 +330,8 @@ func (cm *containerManagerImpl) setupNode() error {
 	return nil
 }
 
-func getContainerNameForProcess(name string) (string, error) {
-	pids, err := getPidsForProcess(name)
+func getContainerNameForProcess(name, pidFile string) (string, error) {
+	pids, err := getPidsForProcess(name, pidFile)
 	if err != nil {
 		return "", fmt.Errorf("failed to detect process id for %q - %v", name, err)
 	}
@@ -418,7 +424,36 @@ func isProcessRunningInHost(pid int) (bool, error) {
 	return initMntNs == processMntNs, nil
 }
 
-func getPidsForProcess(name string) ([]int, error) {
+func getPidFromPidFile(pidFile string) (int, error) {
+	file, err := os.Open(pidFile)
+	if err != nil {
+		return 0, fmt.Errorf("error opening pid file %s: %v", pidFile, err)
+	}
+	defer file.Close()
+
+	data, err := ioutil.ReadAll(file)
+	if err != nil {
+		return 0, fmt.Errorf("error reading pid file %s: %v", pidFile, err)
+	}
+
+	pid, err := strconv.Atoi(string(data))
+	if err != nil {
+		return 0, fmt.Errorf("error parsing %s as a number: %v", string(data), err)
+	}
+
+	return pid, nil
+}
+
+func getPidsForProcess(name, pidFile string) ([]int, error) {
+	if len(pidFile) > 0 {
+		if pid, err := getPidFromPidFile(pidFile); err == nil {
+			return []int{pid}, nil
+		} else {
+			// log the error and fall back to pidof
+			runtime.HandleError(err)
+		}
+	}
+
 	out, err := exec.Command("pidof", name).Output()
 	if err != nil {
 		return []int{}, fmt.Errorf("failed to find pid of %q: %v", name, err)
@@ -438,7 +473,7 @@ func getPidsForProcess(name string) ([]int, error) {
 
 // Ensures that the Docker daemon is in the desired container.
 func ensureDockerInContainer(cadvisor cadvisor.Interface, oomScoreAdj int, manager *fs.Manager) error {
-	pids, err := getPidsForProcess("docker")
+	pids, err := getPidsForProcess(dockerProcessName, dockerPidFile)
 	if err != nil {
 		return err
 	}