Merge pull request #667 from mrunalp/systemd_cgroups

Add support for enabling systemd cgroups

main.go

@@ -79,6 +79,10 @@ func main() {
 			Value: "criu",
 			Usage: "path to the criu binary used for checkpoint and restore",
 		},
+		cli.BoolFlag{
+			Name:  "systemd-cgroup",
+			Usage: "enable systemd cgroup support, expects cgroupsPath to be of form \"slice:prefix:name\" for e.g. \"system.slice:runc:434234\"",
+		},
 	}
 	app.Commands = []cli.Command{
 		checkpointCommand,

man/runc.8.md

@@ -48,5 +48,6 @@ value for "bundle" is the current directory.
    --log-format "text"                          set the format used by logs ('text' (default), or 'json')
    --root "/run/opencontainer/containers"       root directory for storage of container state (this should be located in tmpfs)
    --criu "criu"                                path to the criu binary used for checkpoint and restore
+   --systemd-cgroup                             enable systemd cgroup support, expects cgroupsPath to be of form "slice:prefix:name" for e.g. "system.slice:runc:434234"
    --help, -h                                   show help
    --version, -v                                print the version

restore.go

@@ -92,7 +92,7 @@ using the runc checkpoint command.`,
 		if err != nil {
 			fatal(err)
 		}
-		config, err := createLibcontainerConfig(id, spec)
+		config, err := createLibcontainerConfig(id, context.GlobalBool("systemd-cgroup"), spec)
 		if err != nil {
 			fatal(err)
 		}

spec.go

@@ -248,7 +248,7 @@ func loadSpec(cPath string) (spec *specs.Spec, err error) {
 	return spec, validateProcessSpec(&spec.Process)
 }
 
-func createLibcontainerConfig(cgroupName string, spec *specs.Spec) (*configs.Config, error) {
+func createLibcontainerConfig(cgroupName string, useSystemdCgroup bool, spec *specs.Spec) (*configs.Config, error) {
 	// runc's cwd will always be the bundle path
 	rcwd, err := os.Getwd()
 	if err != nil {
@@ -299,7 +299,7 @@ func createLibcontainerConfig(cgroupName string, spec *specs.Spec) (*configs.Con
 	if err := setupUserNamespace(spec, config); err != nil {
 		return nil, err
 	}
-	c, err := createCgroupConfig(cgroupName, spec)
+	c, err := createCgroupConfig(cgroupName, useSystemdCgroup, spec)
 	if err != nil {
 		return nil, err
 	}
@@ -344,26 +344,47 @@ func createLibcontainerMount(cwd string, m specs.Mount) *configs.Mount {
 	}
 }
 
-func createCgroupConfig(name string, spec *specs.Spec) (*configs.Cgroup, error) {
+func createCgroupConfig(name string, useSystemdCgroup bool, spec *specs.Spec) (*configs.Cgroup, error) {
 	var (
 		err          error
 		myCgroupPath string
 	)
 
+	c := &configs.Cgroup{
+		Resources: &configs.Resources{},
+	}
+
 	if spec.Linux.CgroupsPath != nil {
 		myCgroupPath = libcontainerUtils.CleanPath(*spec.Linux.CgroupsPath)
+	}
+
+	if useSystemdCgroup {
+		if myCgroupPath == "" {
+			c.Parent = "system.slice"
+			c.ScopePrefix = "runc"
+			c.Name = name
 		} else {
+			// Parse the path from expected "slice:prefix:name"
+			// for e.g. "system.slice:docker:1234"
+			parts := strings.Split(myCgroupPath, ":")
+			if len(parts) != 3 {
+				return nil, fmt.Errorf("expected cgroupsPath to be of format \"slice:prefix:name\" for systemd cgroups")
+			}
+			c.Parent = parts[0]
+			c.ScopePrefix = parts[1]
+			c.Name = parts[2]
+		}
+	} else {
+		if myCgroupPath == "" {
 			myCgroupPath, err = cgroups.GetThisCgroupDir("devices")
 			if err != nil {
 				return nil, err
 			}
 			myCgroupPath = filepath.Join(myCgroupPath, name)
 		}
-
-	c := &configs.Cgroup{
-		Path:      myCgroupPath,
-		Resources: &configs.Resources{},
+		c.Path = myCgroupPath
 	}
+
 	c.Resources.AllowedDevices = allowedDevices
 	r := spec.Linux.Resources
 	if r == nil {

spec_test.go

@@ -15,7 +15,7 @@ func TestLinuxCgroupsPathSpecified(t *testing.T) {
 	spec := &specs.Spec{}
 	spec.Linux.CgroupsPath = &cgroupsPath
 
-	cgroup, err := createCgroupConfig("ContainerID", spec)
+	cgroup, err := createCgroupConfig("ContainerID", false, spec)
 	if err != nil {
 		t.Errorf("Couldn't create Cgroup config: %v", err)
 	}
@@ -28,7 +28,7 @@ func TestLinuxCgroupsPathSpecified(t *testing.T) {
 func TestLinuxCgroupsPathNotSpecified(t *testing.T) {
 	spec := &specs.Spec{}
 
-	cgroup, err := createCgroupConfig("ContainerID", spec)
+	cgroup, err := createCgroupConfig("ContainerID", false, spec)
 	if err != nil {
 		t.Errorf("Couldn't create Cgroup config: %v", err)
 	}

utils.go

@@ -12,6 +12,7 @@ import (
 	"github.com/Sirupsen/logrus"
 	"github.com/codegangsta/cli"
 	"github.com/opencontainers/runc/libcontainer"
+	"github.com/opencontainers/runc/libcontainer/cgroups/systemd"
 	"github.com/opencontainers/runc/libcontainer/configs"
 	"github.com/opencontainers/specs/specs-go"
 )
@@ -146,7 +147,15 @@ func loadFactory(context *cli.Context) (libcontainer.Factory, error) {
 	if err != nil {
 		return nil, err
 	}
-	return libcontainer.New(abs, libcontainer.Cgroupfs, func(l *libcontainer.LinuxFactory) error {
+	cgroupManager := libcontainer.Cgroupfs
+	if context.GlobalBool("systemd-cgroup") {
+		if systemd.UseSystemd() {
+			cgroupManager = libcontainer.SystemdCgroups
+		} else {
+			return nil, fmt.Errorf("systemd cgroup flag passed, but systemd support for managing cgroups is not available.")
+		}
+	}
+	return libcontainer.New(abs, cgroupManager, func(l *libcontainer.LinuxFactory) error {
 		l.CriuPath = context.GlobalString("criu")
 		return nil
 	})
@@ -285,7 +294,7 @@ func createPidFile(path string, process *libcontainer.Process) error {
 }
 
 func createContainer(context *cli.Context, id string, spec *specs.Spec) (libcontainer.Container, error) {
-	config, err := createLibcontainerConfig(id, spec)
+	config, err := createLibcontainerConfig(id, context.GlobalBool("systemd-cgroup"), spec)
 	if err != nil {
 		return nil, err
 	}