Remove systemd docker container name check

container/docker/factory.go

@@ -21,17 +21,14 @@ import (
 	"regexp"
 	"strconv"
 	"strings"
-	"sync"
 
 	"github.com/google/cadvisor/container"
 	"github.com/google/cadvisor/container/libcontainer"
 	"github.com/google/cadvisor/fs"
 	info "github.com/google/cadvisor/info/v1"
-	"github.com/google/cadvisor/utils"
 
 	"github.com/fsouza/go-dockerclient"
 	"github.com/golang/glog"
-	"github.com/opencontainers/runc/libcontainer/cgroups"
 )
 
 var ArgDockerEndpoint = flag.String("docker", "unix:///var/run/docker.sock", "docker endpoint")
@@ -46,9 +43,7 @@ var dockerRunDir = flag.String("docker_run", "/var/run/docker", "Absolute path t
 
 // Regexp that identifies docker cgroups, containers started with
 // --cgroup-parent have another prefix than 'docker'
-var dockerCgroupRegexp = regexp.MustCompile(`.+-([a-z0-9]{64})\.scope$`)
-
-var noSystemd = flag.Bool("nosystemd", false, "Explicitly disable systemd support for Docker containers")
+var dockerCgroupRegexp = regexp.MustCompile(`([a-z0-9]{64})`)
 
 var dockerEnvWhitelist = flag.String("docker_env_metadata_whitelist", "", "a comma-separated list of environment variable keys that needs to be collected for docker containers")
 
@@ -58,36 +53,10 @@ func DockerStateDir() string {
 	return libcontainer.DockerStateDir(*dockerRootDir)
 }
 
-// Whether the system is using Systemd.
-var useSystemd = false
-var check = sync.Once{}
-
 const (
 	dockerRootDirKey = "Root Dir"
 )
 
-func UseSystemd() bool {
-	check.Do(func() {
-		if *noSystemd {
-			return
-		}
-		// Check for system.slice in systemd and cpu cgroup.
-		for _, cgroupType := range []string{"name=systemd", "cpu"} {
-			mnt, err := cgroups.FindCgroupMountpoint(cgroupType)
-			if err == nil {
-				// systemd presence does not mean systemd controls cgroups.
-				// If system.slice cgroup exists, then systemd is taking control.
-				// This breaks if user creates system.slice manually :)
-				if utils.FileExists(path.Join(mnt, "system.slice")) {
-					useSystemd = true
-					break
-				}
-			}
-		}
-	})
-	return useSystemd
-}
-
 func RootDir() string {
 	return *dockerRootDir
 }
@@ -150,21 +119,15 @@ func (self *dockerFactory) NewContainerHandler(name string, inHostNamespace bool
 func ContainerNameToDockerId(name string) string {
 	id := path.Base(name)
 
-	// Turn systemd cgroup name into Docker ID.
-	if UseSystemd() {
-		if matches := dockerCgroupRegexp.FindStringSubmatch(id); matches != nil {
-			id = matches[1]
-		}
+	if matches := dockerCgroupRegexp.FindStringSubmatch(id); matches != nil {
+		return matches[1]
 	}
 
 	return id
 }
 
 func isContainerName(name string) bool {
-	if UseSystemd() {
-		return dockerCgroupRegexp.MatchString(path.Base(name))
-	}
-	return true
+	return dockerCgroupRegexp.MatchString(path.Base(name))
 }
 
 // Docker handles all containers under /docker
@@ -216,10 +179,6 @@ func parseDockerVersion(full_version_string string) ([]int, error) {
 
 // Register root container before running this function!
 func Register(factory info.MachineInfoFactory, fsInfo fs.FsInfo) error {
-	if UseSystemd() {
-		glog.Infof("System is using systemd")
-	}
-
 	client, err := Client()
 	if err != nil {
 		return fmt.Errorf("unable to communicate with docker daemon: %v", err)
@@ -278,6 +237,7 @@ func Register(factory info.MachineInfoFactory, fsInfo fs.FsInfo) error {
 		storageDriver:      storageDriver(sd),
 		storageDir:         storageDir,
 	}
+
 	container.RegisterContainerHandlerFactory(f)
 	return nil
 }

validate/validate.go

@@ -192,11 +192,6 @@ func validateDockerInfo() (string, string) {
 			execDriver := info.Get("ExecutionDriver")
 			storageDriver := info.Get("Driver")
 			desc := fmt.Sprintf("Docker exec driver is %s. Storage driver is %s.\n", execDriver, storageDriver)
-			if docker.UseSystemd() {
-				desc += "\tsystemd is being used to create cgroups.\n"
-			} else {
-				desc += "\tCgroups are being created through cgroup filesystem.\n"
-			}
 			if strings.Contains(execDriver, "native") {
 				stateFile := docker.DockerStateDir()
 				if !utils.FileExists(stateFile) {