@@ -345,6 +345,7 @@ func populateCommand(c *Container, env []string) error {

 		MountLabel:         c.GetMountLabel(),

 		LxcConfig:          lxcConfig,

 		AppArmorProfile:    c.AppArmorProfile,

+		CgroupParent:       c.hostConfig.CgroupParent,

 	}

 	return nil

@@ -164,6 +164,7 @@ type Command struct {

 	MountLabel         string            `json:"mount_label"`

 	LxcConfig          []string          `json:"lxc_config"`

 	AppArmorProfile    string            `json:"apparmor_profile"`

+	CgroupParent       string            `json:"cgroup_parent"` // The parent cgroup for this command.

 }

 func InitContainer(c *Command) *configs.Config {

@@ -179,6 +180,11 @@ func InitContainer(c *Command) *configs.Config {

 	// check to see if we are running in ramdisk to disable pivot root

 	container.NoPivotRoot = os.Getenv("DOCKER_RAMDISK") != ""

+

+	// Default parent cgroup is "docker". Override if required.

+	if c.CgroupParent != "" {

+		container.Cgroups.Parent = c.CgroupParent

+	}

 	return container

 }

@@ -131,6 +131,7 @@ type HostConfig struct {

 	ReadonlyRootfs  bool

 	Ulimits         []*ulimit.Ulimit

 	LogConfig       LogConfig

+	CgroupParent    string // Parent cgroup.

 }

 // This is used by the create command when you want to set both the

@@ -182,6 +183,7 @@ func ContainerHostConfigFromJob(job *engine.Job) *HostConfig {

 		IpcMode:         IpcMode(job.Getenv("IpcMode")),

 		PidMode:         PidMode(job.Getenv("PidMode")),

 		ReadonlyRootfs:  job.GetenvBool("ReadonlyRootfs"),

+		CgroupParent:    job.Getenv("CgroupParent"),

 	}

 	// FIXME: This is for backward compatibility, if people use `Cpuset`

@@ -71,6 +71,7 @@ func Parse(cmd *flag.FlagSet, args []string) (*Config, *HostConfig, *flag.FlagSe

 		flRestartPolicy   = cmd.String([]string{"-restart"}, "no", "Restart policy to apply when a container exits")

 		flReadonlyRootfs  = cmd.Bool([]string{"-read-only"}, false, "Mount the container's root filesystem as read only")

 		flLoggingDriver   = cmd.String([]string{"-log-driver"}, "", "Logging driver for container")

+		flCgroupParent    = cmd.String([]string{"-cgroup-parent"}, "", "Optional parent cgroup for the container")

 	)

 	cmd.Var(&flAttach, []string{"a", "-attach"}, "Attach to STDIN, STDOUT or STDERR")

@@ -332,6 +333,7 @@ func Parse(cmd *flag.FlagSet, args []string) (*Config, *HostConfig, *flag.FlagSe

 		ReadonlyRootfs:  *flReadonlyRootfs,

 		Ulimits:         flUlimits.GetList(),

 		LogConfig:       LogConfig{Type: *flLoggingDriver},

+		CgroupParent:    *flCgroupParent,

 	}

 	// When allocating stdin in attached mode, close stdin at client disconnect