Adding option to configure cgroup to start cri-containerd

Signed-off-by: Abhinandan Prativadi <abhi@docker.com>

pkg/server/helpers.go

@@ -24,12 +24,14 @@ import (
 	"strconv"
 	"strings"
 
+	"github.com/containerd/cgroups"
 	"github.com/containerd/containerd/content"
 	"github.com/containerd/containerd/errdefs"
 	"github.com/docker/distribution/reference"
 	imagedigest "github.com/opencontainers/go-digest"
 	"github.com/opencontainers/image-spec/identity"
 	imagespec "github.com/opencontainers/image-spec/specs-go/v1"
+	specs "github.com/opencontainers/runtime-spec/specs-go"
 	"golang.org/x/net/context"
 	"k8s.io/kubernetes/pkg/kubelet/apis/cri/v1alpha1/runtime"
 
@@ -352,3 +354,23 @@ func resolveSymbolicLink(path string) (string, error) {
 	}
 	return filepath.EvalSymlinks(path)
 }
+
+// loadCgroup loads the cgroup associated with path if it exists and moves the current process into the cgroup. If the cgroup
+// is not created it is created and returned.
+func loadCgroup(cgroupPath string) (cgroups.Cgroup, error) {
+	cg, err := cgroups.Load(cgroups.V1, cgroups.StaticPath(cgroupPath))
+	if err != nil {
+		if err != cgroups.ErrCgroupDeleted {
+			return nil, err
+		}
+		if cg, err = cgroups.New(cgroups.V1, cgroups.StaticPath(cgroupPath), &specs.LinuxResources{}); err != nil {
+			return nil, err
+		}
+	}
+	if err := cg.Add(cgroups.Process{
+		Pid: os.Getpid(),
+	}); err != nil {
+		return nil, err
+	}
+	return cg, nil
+}

pkg/server/service.go

@@ -84,6 +84,8 @@ type criContainerdService struct {
 	client *containerd.Client
 	// streamServer is the streaming server serves container streaming request.
 	streamServer streaming.Server
+	// cgroupPath in which the cri-containerd is placed in
+	cgroupPath string
 }
 
 // NewCRIContainerdService returns a new instance of CRIContainerdService
@@ -95,13 +97,20 @@ func NewCRIContainerdService(
 	networkPluginBinDir,
 	networkPluginConfDir,
 	streamAddress,
-	streamPort string) (CRIContainerdService, error) {
+	streamPort string,
+	cgroupPath string) (CRIContainerdService, error) {
 	// TODO(random-liu): [P2] Recover from runtime state and checkpoint.
 
 	client, err := containerd.New(containerdEndpoint, containerd.WithDefaultNamespace(k8sContainerdNamespace))
 	if err != nil {
 		return nil, fmt.Errorf("failed to initialize containerd client with endpoint %q: %v", containerdEndpoint, err)
 	}
+	if cgroupPath != "" {
+		_, err := loadCgroup(cgroupPath)
+		if err != nil {
+			return nil, fmt.Errorf("failed to load cgroup for cgroup path %v: %v", cgroupPath, err)
+		}
+	}
 
 	c := &criContainerdService{
 		os:                  osinterface.RealOS{},
@@ -118,6 +127,7 @@ func NewCRIContainerdService(
 		eventService:        client.EventService(),
 		contentStoreService: client.ContentStore(),
 		client:              client,
+		cgroupPath:          cgroupPath,
 	}
 
 	netPlugin, err := ocicni.InitCNI(networkPluginConfDir, networkPluginBinDir)