Add per-pod CGroups

Pods can now create their own (cgroupfs) cgroups which containers
in them can (optionally) use.

This presently only works with CGroupFS, systemd cgroups are
still WIP

Signed-off-by: Matthew Heon <matthew.heon@gmail.com>

Closes: #784
Approved by: rhatdan

1 files changed, 35 insertions, 0 deletions

diff --git a/libpod/runtime_pod.go b/libpod/runtime_pod.go
index 4ca8da9ee..3872a4b67 100644
--- a/libpod/runtime_pod.go
+++ b/libpod/runtime_pod.go
@@ -2,9 +2,12 @@ package libpod
 
 import (
 	"path"
+	"path/filepath"
 	"strings"
 
+	"github.com/containerd/cgroups"
 	"github.com/pkg/errors"
+	"github.com/sirupsen/logrus"
 )
 
 // Contains the public Runtime API for pods
@@ -56,12 +59,21 @@ func (r *Runtime) NewPod(options ...PodCreateOption) (*Pod, error) {
 		} else if strings.HasSuffix(path.Base(pod.config.CgroupParent), ".slice") {
 			return nil, errors.Wrapf(ErrInvalidArg, "systemd slice received as cgroup parent when using cgroupfs")
 		}
+		// Creating CGroup path is currently a NOOP until proper systemd
+		// cgroup management is merged
 	case SystemdCgroupsManager:
 		if pod.config.CgroupParent == "" {
 			pod.config.CgroupParent = SystemdDefaultCgroupParent
 		} else if len(pod.config.CgroupParent) < 6 || !strings.HasSuffix(path.Base(pod.config.CgroupParent), ".slice") {
 			return nil, errors.Wrapf(ErrInvalidArg, "did not receive systemd slice as cgroup parent when using systemd to manage cgroups")
 		}
+		// If we are set to use pod cgroups, set the cgroup parent that
+		// all containers in the pod will share
+		// No need to create it with cgroupfs - the first container to
+		// launch should do it for us
+		if pod.config.UsePodCgroup {
+			pod.state.CgroupPath = filepath.Join(pod.config.CgroupParent, pod.ID())
+		}
 	default:
 		return nil, errors.Wrapf(ErrInvalidArg, "unsupported CGroup manager: %s - cannot validate cgroup parent", r.config.CgroupManager)
 	}
@@ -211,6 +223,29 @@ func (r *Runtime) RemovePod(p *Pod, removeCtrs, force bool) error {
 		ctr.valid = false
 	}
 
+	// Remove pod cgroup, if present
+	if p.state.CgroupPath != "" {
+		switch p.runtime.config.CgroupManager {
+		case SystemdCgroupsManager:
+			// NOOP for now, until proper systemd cgroup management
+			// is implemented
+		case CgroupfsCgroupsManager:
+			// Delete the cgroupfs cgroup
+			logrus.Debugf("Removing pod cgroup %s", p.state.CgroupPath)
+
+			cgroup, err := cgroups.Load(cgroups.V1, cgroups.StaticPath(p.state.CgroupPath))
+			if err != nil && err != cgroups.ErrCgroupDeleted {
+				return err
+			} else if err == nil {
+				if err := cgroup.Delete(); err != nil {
+					return err
+				}
+			}
+		default:
+			return errors.Wrapf(ErrInvalidArg, "unknown cgroups manager %s specified", p.runtime.config.CgroupManager)
+		}
+	}
+
 	// Remove pod from state
 	if err := r.state.RemovePod(p); err != nil {
 		return err