Add --cgroup-manager flag to Podman binary

Signed-off-by: Matthew Heon <[email protected]>

Closes: containers#507
Approved by: baude

Author: mheon

cmd/podman/libpodruntime/runtime.go

@@ -42,7 +42,10 @@ func GetRuntimeWithStorageOpts(c *cli.Context, storageOpts *storage.StoreOptions
 		options = append(options, libpod.WithConmonPath(c.GlobalString("conmon")))
 	}
 
-	// TODO flag to set CGroup manager?
+	if c.GlobalIsSet("cgroup-manager") {
+		options = append(options, libpod.WithCgroupManager(c.GlobalString("cgroup-manager")))
+	}
+
 	// TODO flag to set libpod static dir?
 	// TODO flag to set libpod tmp dir?
 

cmd/podman/main.go

@@ -108,6 +108,10 @@ func main() {
 		return nil
 	}
 	app.Flags = []cli.Flag{
+		cli.StringFlag{
+			Name:  "cgroup-manager",
+			Usage: "cgroup manager to use (cgroupfs or systemd, default cgroupfs)",
+		},
 		cli.StringFlag{
 			Name:  "cni-config-dir",
 			Usage: "path of the configuration directory for CNI networks",

docs/podman.1.md

@@ -23,6 +23,9 @@ has the capability to debug pods/images created by crio.
 **--help, -h**
   Print usage statement
 
+**--cgroup-manager**
+   CGroup manager to use for container cgroups. Supported values are cgroupfs (default) or systemd. Setting this flag can cause certain commands to break when called on containers created by the other CGroup manager type.
+
 **--config value, -c**=**"config.file"**
    Path of a config file detailing container server configuration options
 

libpod/container_internal.go

@@ -1133,7 +1133,9 @@ func (c *Container) generateSpec(ctx context.Context) (*spec.Spec, error) {
 		// When runc is set to use Systemd as a cgroup manager, it
 		// expects cgroups to be passed as follows:
 		// slice:prefix:name
-		g.SetLinuxCgroupsPath(path.Base(c.config.CgroupParent) + ":" + "libpod" + ":" + c.ID())
+		systemdCgroups := fmt.Sprintf("%s:libpod:%s", path.Base(c.config.CgroupParent), c.ID())
+		logrus.Debugf("Setting CGroups for container %s to %s", c.ID(), systemdCgroups)
+		g.SetLinuxCgroupsPath(systemdCgroups)
 	} else {
 		cgroupPath, err := c.CGroupPath()
 		if err != nil {

libpod/oci.go

@@ -321,7 +321,7 @@ func (r *OCIRuntime) createOCIContainer(ctr *Container, cgroupParent string) (er
 
 	// Move conmon to specified cgroup
 	if r.cgroupManager == SystemdCgroupsManager {
-		unitName := createUnitName("libpod", ctr.ID())
+		unitName := createUnitName("libpod-conmon", ctr.ID())
 
 		logrus.Infof("Running conmon under slice %s and unitName %s", cgroupParent, unitName)
 		if err = utils.RunUnderSystemdScope(cmd.Process.Pid, cgroupParent, unitName); err != nil {

libpod/options.go

@@ -152,6 +152,11 @@ func WithCgroupManager(manager string) RuntimeOption {
 			return ErrRuntimeFinalized
 		}
 
+		if manager != CgroupfsCgroupsManager && manager != SystemdCgroupsManager {
+			return errors.Wrapf(ErrInvalidArg, "CGroup manager must be one of %s and %s",
+				CgroupfsCgroupsManager, SystemdCgroupsManager)
+		}
+
 		rt.config.CgroupManager = manager
 
 		return nil

libpod/runtime.go

@@ -158,7 +158,7 @@ var (
 		ConmonEnvVars: []string{
 			"PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin",
 		},
-		CgroupManager: "cgroupfs",
+		CgroupManager: CgroupfsCgroupsManager,
 		HooksDir:      hooks.DefaultHooksDir,
 		StaticDir:     filepath.Join(storage.DefaultStoreOptions.GraphRoot, "libpod"),
 		TmpDir:        "/var/run/libpod",