Add rootfs service

Add rootfs service to allow creation of rootfs from layer array

Signed-off-by: Derek McGowan <derek@mcgstyle.net> (github: dmcgowan)

services/rootfs/service.go

@@ -0,0 +1,86 @@
+package rootfs
+
+import (
+	"syscall"
+
+	"github.com/docker/containerd"
+	rootfsapi "github.com/docker/containerd/api/services/rootfs"
+	"github.com/docker/containerd/content"
+	"github.com/docker/containerd/log"
+	"github.com/docker/containerd/plugin"
+	"github.com/docker/containerd/rootfs"
+	"github.com/docker/containerd/snapshot"
+	digest "github.com/opencontainers/go-digest"
+	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
+	"golang.org/x/net/context"
+	"google.golang.org/grpc"
+)
+
+func init() {
+	plugin.Register("rootfs-grpc", &plugin.Registration{
+		Type: plugin.GRPCPlugin,
+		Init: func(ic *plugin.InitContext) (interface{}, error) {
+			return NewService(ic.Store, ic.Snapshotter)
+		},
+	})
+}
+
+type Service struct {
+	store       *content.Store
+	snapshotter snapshot.Snapshotter
+}
+
+func NewService(store *content.Store, snapshotter snapshot.Snapshotter) (*Service, error) {
+	return &Service{
+		store:       store,
+		snapshotter: snapshotter,
+	}, nil
+}
+
+func (s *Service) Register(gs *grpc.Server) error {
+	rootfsapi.RegisterRootFSServer(gs, s)
+	return nil
+}
+
+func (s *Service) Prepare(ctx context.Context, pr *rootfsapi.PrepareRequest) (*rootfsapi.PrepareResponse, error) {
+	layers := make([]ocispec.Descriptor, len(pr.Layers))
+	for i, l := range pr.Layers {
+		layers[i] = ocispec.Descriptor{
+			MediaType: l.MediaType,
+			Digest:    l.Digest,
+			Size:      l.MediaSize,
+		}
+	}
+	log.G(ctx).Infof("Preparing %#v", layers)
+	chainID, err := rootfs.Prepare(ctx, s.snapshotter, mounter{}, layers, s.store.Reader, emptyResolver, noopRegister)
+	if err != nil {
+		log.G(ctx).Errorf("Rootfs Prepare failed!: %v", err)
+		return nil, err
+	}
+	log.G(ctx).Infof("ChainID %#v", chainID)
+	return &rootfsapi.PrepareResponse{
+		ChainID: chainID,
+	}, nil
+}
+
+type mounter struct{}
+
+func (mounter) Mount(dir string, mounts ...containerd.Mount) error {
+	return containerd.MountAll(mounts, dir)
+}
+
+func (mounter) Unmount(dir string) error {
+	return syscall.Unmount(dir, 0)
+}
+
+func emptyResolver(digest.Digest) digest.Digest {
+	return digest.Digest("")
+}
+
+func noopRegister(digest.Digest, digest.Digest) error {
+	return nil
+}
+
+//func (s *Service) Mounts(ctx context.Context, mr *rootfsapi.MountRequest) (*rootfsapi.MountResponse, error) {
+//
+//}