Add service plugin and support in process integration.

Signed-off-by: Lantao Liu <lantaol@google.com>

services/containers/local.go

@@ -0,0 +1,189 @@
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package containers
+
+import (
+	"github.com/boltdb/bolt"
+	eventstypes "github.com/containerd/containerd/api/events"
+	api "github.com/containerd/containerd/api/services/containers/v1"
+	"github.com/containerd/containerd/containers"
+	"github.com/containerd/containerd/errdefs"
+	"github.com/containerd/containerd/events"
+	"github.com/containerd/containerd/metadata"
+	"github.com/containerd/containerd/plugin"
+	"github.com/containerd/containerd/services"
+	ptypes "github.com/gogo/protobuf/types"
+	"golang.org/x/net/context"
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/status"
+)
+
+func init() {
+	plugin.Register(&plugin.Registration{
+		Type: plugin.ServicePlugin,
+		ID:   services.ContainersService,
+		Requires: []plugin.Type{
+			plugin.MetadataPlugin,
+		},
+		InitFn: func(ic *plugin.InitContext) (interface{}, error) {
+			m, err := ic.Get(plugin.MetadataPlugin)
+			if err != nil {
+				return nil, err
+			}
+			return &local{
+				db:        m.(*metadata.DB),
+				publisher: ic.Events,
+			}, nil
+		},
+	})
+}
+
+type local struct {
+	db        *metadata.DB
+	publisher events.Publisher
+}
+
+var _ api.ContainersClient = &local{}
+
+func (l *local) Get(ctx context.Context, req *api.GetContainerRequest, _ ...grpc.CallOption) (*api.GetContainerResponse, error) {
+	var resp api.GetContainerResponse
+
+	return &resp, errdefs.ToGRPC(l.withStoreView(ctx, func(ctx context.Context, store containers.Store) error {
+		container, err := store.Get(ctx, req.ID)
+		if err != nil {
+			return err
+		}
+		containerpb := containerToProto(&container)
+		resp.Container = containerpb
+
+		return nil
+	}))
+}
+
+func (l *local) List(ctx context.Context, req *api.ListContainersRequest, _ ...grpc.CallOption) (*api.ListContainersResponse, error) {
+	var resp api.ListContainersResponse
+
+	return &resp, errdefs.ToGRPC(l.withStoreView(ctx, func(ctx context.Context, store containers.Store) error {
+		containers, err := store.List(ctx, req.Filters...)
+		if err != nil {
+			return err
+		}
+
+		resp.Containers = containersToProto(containers)
+		return nil
+	}))
+}
+
+func (l *local) Create(ctx context.Context, req *api.CreateContainerRequest, _ ...grpc.CallOption) (*api.CreateContainerResponse, error) {
+	var resp api.CreateContainerResponse
+
+	if err := l.withStoreUpdate(ctx, func(ctx context.Context, store containers.Store) error {
+		container := containerFromProto(&req.Container)
+
+		created, err := store.Create(ctx, container)
+		if err != nil {
+			return err
+		}
+
+		resp.Container = containerToProto(&created)
+
+		return nil
+	}); err != nil {
+		return &resp, errdefs.ToGRPC(err)
+	}
+	if err := l.publisher.Publish(ctx, "/containers/create", &eventstypes.ContainerCreate{
+		ID:    resp.Container.ID,
+		Image: resp.Container.Image,
+		Runtime: &eventstypes.ContainerCreate_Runtime{
+			Name:    resp.Container.Runtime.Name,
+			Options: resp.Container.Runtime.Options,
+		},
+	}); err != nil {
+		return &resp, err
+	}
+
+	return &resp, nil
+}
+
+func (l *local) Update(ctx context.Context, req *api.UpdateContainerRequest, _ ...grpc.CallOption) (*api.UpdateContainerResponse, error) {
+	if req.Container.ID == "" {
+		return nil, status.Errorf(codes.InvalidArgument, "Container.ID required")
+	}
+	var (
+		resp      api.UpdateContainerResponse
+		container = containerFromProto(&req.Container)
+	)
+
+	if err := l.withStoreUpdate(ctx, func(ctx context.Context, store containers.Store) error {
+		var fieldpaths []string
+		if req.UpdateMask != nil && len(req.UpdateMask.Paths) > 0 {
+			for _, path := range req.UpdateMask.Paths {
+				fieldpaths = append(fieldpaths, path)
+			}
+		}
+
+		updated, err := store.Update(ctx, container, fieldpaths...)
+		if err != nil {
+			return err
+		}
+
+		resp.Container = containerToProto(&updated)
+		return nil
+	}); err != nil {
+		return &resp, errdefs.ToGRPC(err)
+	}
+
+	if err := l.publisher.Publish(ctx, "/containers/update", &eventstypes.ContainerUpdate{
+		ID:          resp.Container.ID,
+		Image:       resp.Container.Image,
+		Labels:      resp.Container.Labels,
+		SnapshotKey: resp.Container.SnapshotKey,
+	}); err != nil {
+		return &resp, err
+	}
+
+	return &resp, nil
+}
+
+func (l *local) Delete(ctx context.Context, req *api.DeleteContainerRequest, _ ...grpc.CallOption) (*ptypes.Empty, error) {
+	if err := l.withStoreUpdate(ctx, func(ctx context.Context, store containers.Store) error {
+		return store.Delete(ctx, req.ID)
+	}); err != nil {
+		return &ptypes.Empty{}, errdefs.ToGRPC(err)
+	}
+
+	if err := l.publisher.Publish(ctx, "/containers/delete", &eventstypes.ContainerDelete{
+		ID: req.ID,
+	}); err != nil {
+		return &ptypes.Empty{}, err
+	}
+
+	return &ptypes.Empty{}, nil
+}
+
+func (l *local) withStore(ctx context.Context, fn func(ctx context.Context, store containers.Store) error) func(tx *bolt.Tx) error {
+	return func(tx *bolt.Tx) error { return fn(ctx, metadata.NewContainerStore(tx)) }
+}
+
+func (l *local) withStoreView(ctx context.Context, fn func(ctx context.Context, store containers.Store) error) error {
+	return l.db.View(l.withStore(ctx, fn))
+}
+
+func (l *local) withStoreUpdate(ctx context.Context, fn func(ctx context.Context, store containers.Store) error) error {
+	return l.db.Update(l.withStore(ctx, fn))
+}

services/containers/service.go

@@ -17,19 +17,13 @@
 package containers
 
 import (
-	"github.com/boltdb/bolt"
-	eventstypes "github.com/containerd/containerd/api/events"
 	api "github.com/containerd/containerd/api/services/containers/v1"
-	"github.com/containerd/containerd/containers"
-	"github.com/containerd/containerd/errdefs"
-	"github.com/containerd/containerd/events"
-	"github.com/containerd/containerd/metadata"
 	"github.com/containerd/containerd/plugin"
+	"github.com/containerd/containerd/services"
 	ptypes "github.com/gogo/protobuf/types"
+	"github.com/pkg/errors"
 	"golang.org/x/net/context"
 	"google.golang.org/grpc"
-	"google.golang.org/grpc/codes"
-	"google.golang.org/grpc/status"
 )
 
 func init() {
@@ -37,27 +31,31 @@ func init() {
 		Type: plugin.GRPCPlugin,
 		ID:   "containers",
 		Requires: []plugin.Type{
-			plugin.MetadataPlugin,
+			plugin.ServicePlugin,
 		},
 		InitFn: func(ic *plugin.InitContext) (interface{}, error) {
-			m, err := ic.Get(plugin.MetadataPlugin)
+			plugins, err := ic.GetByType(plugin.ServicePlugin)
 			if err != nil {
 				return nil, err
 			}
-			return NewService(m.(*metadata.DB), ic.Events), nil
+			p, ok := plugins[services.ContainersService]
+			if !ok {
+				return nil, errors.New("containers service not found")
+			}
+			i, err := p.Instance()
+			if err != nil {
+				return nil, err
+			}
+			return &service{local: i.(api.ContainersClient)}, nil
 		},
 	})
 }
 
 type service struct {
-	db        *metadata.DB
-	publisher events.Publisher
+	local api.ContainersClient
 }
 
-// NewService returns the container GRPC server
-func NewService(db *metadata.DB, publisher events.Publisher) api.ContainersServer {
-	return &service{db: db, publisher: publisher}
-}
+var _ api.ContainersServer = &service{}
 
 func (s *service) Register(server *grpc.Server) error {
 	api.RegisterContainersServer(server, s)
@@ -65,129 +63,21 @@ func (s *service) Register(server *grpc.Server) error {
 }
 
 func (s *service) Get(ctx context.Context, req *api.GetContainerRequest) (*api.GetContainerResponse, error) {
-	var resp api.GetContainerResponse
-
-	return &resp, errdefs.ToGRPC(s.withStoreView(ctx, func(ctx context.Context, store containers.Store) error {
-		container, err := store.Get(ctx, req.ID)
-		if err != nil {
-			return err
-		}
-		containerpb := containerToProto(&container)
-		resp.Container = containerpb
-
-		return nil
-	}))
+	return s.local.Get(ctx, req)
 }
 
 func (s *service) List(ctx context.Context, req *api.ListContainersRequest) (*api.ListContainersResponse, error) {
-	var resp api.ListContainersResponse
-
-	return &resp, errdefs.ToGRPC(s.withStoreView(ctx, func(ctx context.Context, store containers.Store) error {
-		containers, err := store.List(ctx, req.Filters...)
-		if err != nil {
-			return err
-		}
-
-		resp.Containers = containersToProto(containers)
-		return nil
-	}))
+	return s.local.List(ctx, req)
 }
 
 func (s *service) Create(ctx context.Context, req *api.CreateContainerRequest) (*api.CreateContainerResponse, error) {
-	var resp api.CreateContainerResponse
-
-	if err := s.withStoreUpdate(ctx, func(ctx context.Context, store containers.Store) error {
-		container := containerFromProto(&req.Container)
-
-		created, err := store.Create(ctx, container)
-		if err != nil {
-			return err
-		}
-
-		resp.Container = containerToProto(&created)
-
-		return nil
-	}); err != nil {
-		return &resp, errdefs.ToGRPC(err)
-	}
-	if err := s.publisher.Publish(ctx, "/containers/create", &eventstypes.ContainerCreate{
-		ID:    resp.Container.ID,
-		Image: resp.Container.Image,
-		Runtime: &eventstypes.ContainerCreate_Runtime{
-			Name:    resp.Container.Runtime.Name,
-			Options: resp.Container.Runtime.Options,
-		},
-	}); err != nil {
-		return &resp, err
-	}
-
-	return &resp, nil
+	return s.local.Create(ctx, req)
 }
 
 func (s *service) Update(ctx context.Context, req *api.UpdateContainerRequest) (*api.UpdateContainerResponse, error) {
-	if req.Container.ID == "" {
-		return nil, status.Errorf(codes.InvalidArgument, "Container.ID required")
-	}
-	var (
-		resp      api.UpdateContainerResponse
-		container = containerFromProto(&req.Container)
-	)
-
-	if err := s.withStoreUpdate(ctx, func(ctx context.Context, store containers.Store) error {
-		var fieldpaths []string
-		if req.UpdateMask != nil && len(req.UpdateMask.Paths) > 0 {
-			for _, path := range req.UpdateMask.Paths {
-				fieldpaths = append(fieldpaths, path)
-			}
-		}
-
-		updated, err := store.Update(ctx, container, fieldpaths...)
-		if err != nil {
-			return err
-		}
-
-		resp.Container = containerToProto(&updated)
-		return nil
-	}); err != nil {
-		return &resp, errdefs.ToGRPC(err)
-	}
-
-	if err := s.publisher.Publish(ctx, "/containers/update", &eventstypes.ContainerUpdate{
-		ID:          resp.Container.ID,
-		Image:       resp.Container.Image,
-		Labels:      resp.Container.Labels,
-		SnapshotKey: resp.Container.SnapshotKey,
-	}); err != nil {
-		return &resp, err
-	}
-
-	return &resp, nil
+	return s.local.Update(ctx, req)
 }
 
 func (s *service) Delete(ctx context.Context, req *api.DeleteContainerRequest) (*ptypes.Empty, error) {
-	if err := s.withStoreUpdate(ctx, func(ctx context.Context, store containers.Store) error {
-		return store.Delete(ctx, req.ID)
-	}); err != nil {
-		return &ptypes.Empty{}, errdefs.ToGRPC(err)
-	}
-
-	if err := s.publisher.Publish(ctx, "/containers/delete", &eventstypes.ContainerDelete{
-		ID: req.ID,
-	}); err != nil {
-		return &ptypes.Empty{}, err
-	}
-
-	return &ptypes.Empty{}, nil
-}
-
-func (s *service) withStore(ctx context.Context, fn func(ctx context.Context, store containers.Store) error) func(tx *bolt.Tx) error {
-	return func(tx *bolt.Tx) error { return fn(ctx, metadata.NewContainerStore(tx)) }
-}
-
-func (s *service) withStoreView(ctx context.Context, fn func(ctx context.Context, store containers.Store) error) error {
-	return s.db.View(s.withStore(ctx, fn))
-}
-
-func (s *service) withStoreUpdate(ctx context.Context, fn func(ctx context.Context, store containers.Store) error) error {
-	return s.db.Update(s.withStore(ctx, fn))
+	return s.local.Delete(ctx, req)
 }

services/content/service.go

@@ -20,14 +20,12 @@ import (
 	"io"
 	"sync"
 
-	eventstypes "github.com/containerd/containerd/api/events"
 	api "github.com/containerd/containerd/api/services/content/v1"
 	"github.com/containerd/containerd/content"
 	"github.com/containerd/containerd/errdefs"
-	"github.com/containerd/containerd/events"
 	"github.com/containerd/containerd/log"
-	"github.com/containerd/containerd/metadata"
 	"github.com/containerd/containerd/plugin"
+	"github.com/containerd/containerd/services"
 	ptypes "github.com/gogo/protobuf/types"
 	digest "github.com/opencontainers/go-digest"
 	"github.com/pkg/errors"
@@ -39,8 +37,7 @@ import (
 )
 
 type service struct {
-	store     content.Store
-	publisher events.Publisher
+	store content.Store
 }
 
 var bufPool = sync.Pool{
@@ -57,26 +54,29 @@ func init() {
 		Type: plugin.GRPCPlugin,
 		ID:   "content",
 		Requires: []plugin.Type{
-			plugin.MetadataPlugin,
+			plugin.ServicePlugin,
 		},
 		InitFn: func(ic *plugin.InitContext) (interface{}, error) {
-			m, err := ic.Get(plugin.MetadataPlugin)
+			plugins, err := ic.GetByType(plugin.ServicePlugin)
 			if err != nil {
 				return nil, err
 			}
-
-			s, err := NewService(m.(*metadata.DB).ContentStore(), ic.Events)
-			return s, err
+			p, ok := plugins[services.ContentService]
+			if !ok {
+				return nil, errors.New("content store service not found")
+			}
+			cs, err := p.Instance()
+			if err != nil {
+				return nil, err
+			}
+			return newService(cs.(content.Store)), nil
 		},
 	})
 }
 
-// NewService returns the content GRPC server
-func NewService(cs content.Store, publisher events.Publisher) (api.ContentServer, error) {
-	return &service{
-		store:     cs,
-		publisher: publisher,
-	}, nil
+// newService returns the content GRPC server
+func newService(cs content.Store) api.ContentServer {
+	return &service{store: cs}
 }
 
 func (s *service) Register(server *grpc.Server) error {
@@ -166,12 +166,6 @@ func (s *service) Delete(ctx context.Context, req *api.DeleteContentRequest) (*p
 		return nil, errdefs.ToGRPC(err)
 	}
 
-	if err := s.publisher.Publish(ctx, "/content/delete", &eventstypes.ContentDelete{
-		Digest: req.Digest,
-	}); err != nil {
-		return nil, err
-	}
-
 	return &ptypes.Empty{}, nil
 }
 

services/content/store.go

@@ -0,0 +1,71 @@
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package content
+
+import (
+	"context"
+
+	eventstypes "github.com/containerd/containerd/api/events"
+	"github.com/containerd/containerd/content"
+	"github.com/containerd/containerd/events"
+	"github.com/containerd/containerd/metadata"
+	"github.com/containerd/containerd/plugin"
+	"github.com/containerd/containerd/services"
+	digest "github.com/opencontainers/go-digest"
+)
+
+// store wraps content.Store with proper event published.
+type store struct {
+	content.Store
+	publisher events.Publisher
+}
+
+func init() {
+	plugin.Register(&plugin.Registration{
+		Type: plugin.ServicePlugin,
+		ID:   services.ContentService,
+		Requires: []plugin.Type{
+			plugin.MetadataPlugin,
+		},
+		InitFn: func(ic *plugin.InitContext) (interface{}, error) {
+			m, err := ic.Get(plugin.MetadataPlugin)
+			if err != nil {
+				return nil, err
+			}
+
+			s, err := newContentStore(m.(*metadata.DB).ContentStore(), ic.Events)
+			return s, err
+		},
+	})
+}
+
+func newContentStore(cs content.Store, publisher events.Publisher) (content.Store, error) {
+	return &store{
+		Store:     cs,
+		publisher: publisher,
+	}, nil
+}
+
+func (s *store) Delete(ctx context.Context, dgst digest.Digest) error {
+	if err := s.Store.Delete(ctx, dgst); err != nil {
+		return err
+	}
+	// TODO: Consider whether we should return error here.
+	return s.publisher.Publish(ctx, "/content/delete", &eventstypes.ContentDelete{
+		Digest: dgst,
+	})
+}

services/diff/local.go

@@ -0,0 +1,178 @@
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package diff
+
+import (
+	diffapi "github.com/containerd/containerd/api/services/diff/v1"
+	"github.com/containerd/containerd/api/types"
+	"github.com/containerd/containerd/diff"
+	"github.com/containerd/containerd/errdefs"
+	"github.com/containerd/containerd/mount"
+	"github.com/containerd/containerd/plugin"
+	"github.com/containerd/containerd/services"
+	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
+	"github.com/pkg/errors"
+	"golang.org/x/net/context"
+	"google.golang.org/grpc"
+)
+
+type config struct {
+	// Order is the order of preference in which to try diff algorithms, the
+	// first differ which is supported is used.
+	// Note when multiple differs may be supported, this order will be
+	// respected for which is choosen. Each differ should return the same
+	// correct output, allowing any ordering to be used to prefer
+	// more optimimal implementations.
+	Order []string `toml:"default"`
+}
+
+type differ interface {
+	diff.Comparer
+	diff.Applier
+}
+
+func init() {
+	plugin.Register(&plugin.Registration{
+		Type: plugin.ServicePlugin,
+		ID:   services.DiffService,
+		Requires: []plugin.Type{
+			plugin.DiffPlugin,
+		},
+		Config: defaultDifferConfig,
+		InitFn: func(ic *plugin.InitContext) (interface{}, error) {
+			differs, err := ic.GetByType(plugin.DiffPlugin)
+			if err != nil {
+				return nil, err
+			}
+
+			orderedNames := ic.Config.(*config).Order
+			ordered := make([]differ, len(orderedNames))
+			for i, n := range orderedNames {
+				differp, ok := differs[n]
+				if !ok {
+					return nil, errors.Errorf("needed differ not loaded: %s", n)
+				}
+				d, err := differp.Instance()
+				if err != nil {
+					return nil, errors.Wrapf(err, "could not load required differ due plugin init error: %s", n)
+				}
+
+				ordered[i], ok = d.(differ)
+				if !ok {
+					return nil, errors.Errorf("differ does not implement Comparer and Applier interface: %s", n)
+				}
+			}
+
+			return &local{
+				differs: ordered,
+			}, nil
+		},
+	})
+}
+
+type local struct {
+	differs []differ
+}
+
+var _ diffapi.DiffClient = &local{}
+
+func (l *local) Apply(ctx context.Context, er *diffapi.ApplyRequest, _ ...grpc.CallOption) (*diffapi.ApplyResponse, error) {
+	var (
+		ocidesc ocispec.Descriptor
+		err     error
+		desc    = toDescriptor(er.Diff)
+		mounts  = toMounts(er.Mounts)
+	)
+
+	for _, differ := range l.differs {
+		ocidesc, err = differ.Apply(ctx, desc, mounts)
+		if !errdefs.IsNotImplemented(err) {
+			break
+		}
+	}
+
+	if err != nil {
+		return nil, errdefs.ToGRPC(err)
+	}
+
+	return &diffapi.ApplyResponse{
+		Applied: fromDescriptor(ocidesc),
+	}, nil
+
+}
+
+func (l *local) Diff(ctx context.Context, dr *diffapi.DiffRequest, _ ...grpc.CallOption) (*diffapi.DiffResponse, error) {
+	var (
+		ocidesc ocispec.Descriptor
+		err     error
+		aMounts = toMounts(dr.Left)
+		bMounts = toMounts(dr.Right)
+	)
+
+	var opts []diff.Opt
+	if dr.MediaType != "" {
+		opts = append(opts, diff.WithMediaType(dr.MediaType))
+	}
+	if dr.Ref != "" {
+		opts = append(opts, diff.WithReference(dr.Ref))
+	}
+	if dr.Labels != nil {
+		opts = append(opts, diff.WithLabels(dr.Labels))
+	}
+
+	for _, d := range l.differs {
+		ocidesc, err = d.Compare(ctx, aMounts, bMounts, opts...)
+		if !errdefs.IsNotImplemented(err) {
+			break
+		}
+	}
+	if err != nil {
+		return nil, errdefs.ToGRPC(err)
+	}
+
+	return &diffapi.DiffResponse{
+		Diff: fromDescriptor(ocidesc),
+	}, nil
+}
+
+func toMounts(apim []*types.Mount) []mount.Mount {
+	mounts := make([]mount.Mount, len(apim))
+	for i, m := range apim {
+		mounts[i] = mount.Mount{
+			Type:    m.Type,
+			Source:  m.Source,
+			Options: m.Options,
+		}
+	}
+	return mounts
+}
+
+func toDescriptor(d *types.Descriptor) ocispec.Descriptor {
+	return ocispec.Descriptor{
+		MediaType: d.MediaType,
+		Digest:    d.Digest,
+		Size:      d.Size_,
+	}
+}
+
+func fromDescriptor(d ocispec.Descriptor) *types.Descriptor {
+	return &types.Descriptor{
+		MediaType: d.MediaType,
+		Digest:    d.Digest,
+		Size_:     d.Size,
+	}
+}

services/diff/service.go

@@ -18,163 +18,53 @@ package diff
 
 import (
 	diffapi "github.com/containerd/containerd/api/services/diff/v1"
-	"github.com/containerd/containerd/api/types"
-	"github.com/containerd/containerd/diff"
-	"github.com/containerd/containerd/errdefs"
-	"github.com/containerd/containerd/mount"
 	"github.com/containerd/containerd/plugin"
-	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
+	"github.com/containerd/containerd/services"
 	"github.com/pkg/errors"
 	"golang.org/x/net/context"
 	"google.golang.org/grpc"
 )
 
-type config struct {
-	// Order is the order of preference in which to try diff algorithms, the
-	// first differ which is supported is used.
-	// Note when multiple differs may be supported, this order will be
-	// respected for which is choosen. Each differ should return the same
-	// correct output, allowing any ordering to be used to prefer
-	// more optimimal implementations.
-	Order []string `toml:"default"`
-}
-
-type differ interface {
-	diff.Comparer
-	diff.Applier
-}
-
 func init() {
 	plugin.Register(&plugin.Registration{
 		Type: plugin.GRPCPlugin,
 		ID:   "diff",
 		Requires: []plugin.Type{
-			plugin.DiffPlugin,
+			plugin.ServicePlugin,
 		},
-		Config: defaultDifferConfig,
 		InitFn: func(ic *plugin.InitContext) (interface{}, error) {
-			differs, err := ic.GetByType(plugin.DiffPlugin)
+			plugins, err := ic.GetByType(plugin.ServicePlugin)
 			if err != nil {
 				return nil, err
 			}
-
-			orderedNames := ic.Config.(*config).Order
-			ordered := make([]differ, len(orderedNames))
-			for i, n := range orderedNames {
-				differp, ok := differs[n]
-				if !ok {
-					return nil, errors.Errorf("needed differ not loaded: %s", n)
-				}
-				d, err := differp.Instance()
-				if err != nil {
-					return nil, errors.Wrapf(err, "could not load required differ due plugin init error: %s", n)
-				}
-
-				ordered[i], ok = d.(differ)
-				if !ok {
-					return nil, errors.Errorf("differ does not implement Comparer and Applier interface: %s", n)
-				}
+			p, ok := plugins[services.DiffService]
+			if !ok {
+				return nil, errors.New("diff service not found")
 			}
-
-			return &service{
-				differs: ordered,
-			}, nil
+			i, err := p.Instance()
+			if err != nil {
+				return nil, err
+			}
+			return &service{local: i.(diffapi.DiffClient)}, nil
 		},
 	})
 }
 
 type service struct {
-	differs []differ
+	local diffapi.DiffClient
 }
 
+var _ diffapi.DiffServer = &service{}
+
 func (s *service) Register(gs *grpc.Server) error {
 	diffapi.RegisterDiffServer(gs, s)
 	return nil
 }
 
 func (s *service) Apply(ctx context.Context, er *diffapi.ApplyRequest) (*diffapi.ApplyResponse, error) {
-	var (
-		ocidesc ocispec.Descriptor
-		err     error
-		desc    = toDescriptor(er.Diff)
-		mounts  = toMounts(er.Mounts)
-	)
-
-	for _, differ := range s.differs {
-		ocidesc, err = differ.Apply(ctx, desc, mounts)
-		if !errdefs.IsNotImplemented(err) {
-			break
-		}
-	}
-
-	if err != nil {
-		return nil, errdefs.ToGRPC(err)
-	}
-
-	return &diffapi.ApplyResponse{
-		Applied: fromDescriptor(ocidesc),
-	}, nil
-
+	return s.local.Apply(ctx, er)
 }
 
 func (s *service) Diff(ctx context.Context, dr *diffapi.DiffRequest) (*diffapi.DiffResponse, error) {
-	var (
-		ocidesc ocispec.Descriptor
-		err     error
-		aMounts = toMounts(dr.Left)
-		bMounts = toMounts(dr.Right)
-	)
-
-	var opts []diff.Opt
-	if dr.MediaType != "" {
-		opts = append(opts, diff.WithMediaType(dr.MediaType))
-	}
-	if dr.Ref != "" {
-		opts = append(opts, diff.WithReference(dr.Ref))
-	}
-	if dr.Labels != nil {
-		opts = append(opts, diff.WithLabels(dr.Labels))
-	}
-
-	for _, d := range s.differs {
-		ocidesc, err = d.Compare(ctx, aMounts, bMounts, opts...)
-		if !errdefs.IsNotImplemented(err) {
-			break
-		}
-	}
-	if err != nil {
-		return nil, errdefs.ToGRPC(err)
-	}
-
-	return &diffapi.DiffResponse{
-		Diff: fromDescriptor(ocidesc),
-	}, nil
-}
-
-func toMounts(apim []*types.Mount) []mount.Mount {
-	mounts := make([]mount.Mount, len(apim))
-	for i, m := range apim {
-		mounts[i] = mount.Mount{
-			Type:    m.Type,
-			Source:  m.Source,
-			Options: m.Options,
-		}
-	}
-	return mounts
-}
-
-func toDescriptor(d *types.Descriptor) ocispec.Descriptor {
-	return ocispec.Descriptor{
-		MediaType: d.MediaType,
-		Digest:    d.Digest,
-		Size:      d.Size_,
-	}
-}
-
-func fromDescriptor(d ocispec.Descriptor) *types.Descriptor {
-	return &types.Descriptor{
-		MediaType: d.MediaType,
-		Digest:    d.Digest,
-		Size_:     d.Size,
-	}
+	return s.local.Diff(ctx, dr)
 }

services/images/local.go

@@ -0,0 +1,183 @@
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package images
+
+import (
+	gocontext "context"
+
+	eventstypes "github.com/containerd/containerd/api/events"
+	imagesapi "github.com/containerd/containerd/api/services/images/v1"
+	"github.com/containerd/containerd/errdefs"
+	"github.com/containerd/containerd/events"
+	"github.com/containerd/containerd/gc"
+	"github.com/containerd/containerd/images"
+	"github.com/containerd/containerd/log"
+	"github.com/containerd/containerd/metadata"
+	"github.com/containerd/containerd/plugin"
+	"github.com/containerd/containerd/services"
+	ptypes "github.com/gogo/protobuf/types"
+	"golang.org/x/net/context"
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/status"
+)
+
+func init() {
+	plugin.Register(&plugin.Registration{
+		Type: plugin.ServicePlugin,
+		ID:   services.ImagesService,
+		Requires: []plugin.Type{
+			plugin.MetadataPlugin,
+			plugin.GCPlugin,
+		},
+		InitFn: func(ic *plugin.InitContext) (interface{}, error) {
+			m, err := ic.Get(plugin.MetadataPlugin)
+			if err != nil {
+				return nil, err
+			}
+			g, err := ic.Get(plugin.GCPlugin)
+			if err != nil {
+				return nil, err
+			}
+
+			return &local{
+				store:     metadata.NewImageStore(m.(*metadata.DB)),
+				publisher: ic.Events,
+				gc:        g.(gcScheduler),
+			}, nil
+		},
+	})
+}
+
+type gcScheduler interface {
+	ScheduleAndWait(gocontext.Context) (gc.Stats, error)
+}
+
+type local struct {
+	store     images.Store
+	gc        gcScheduler
+	publisher events.Publisher
+}
+
+var _ imagesapi.ImagesClient = &local{}
+
+func (l *local) Get(ctx context.Context, req *imagesapi.GetImageRequest, _ ...grpc.CallOption) (*imagesapi.GetImageResponse, error) {
+	image, err := l.store.Get(ctx, req.Name)
+	if err != nil {
+		return nil, errdefs.ToGRPC(err)
+	}
+
+	imagepb := imageToProto(&image)
+	return &imagesapi.GetImageResponse{
+		Image: &imagepb,
+	}, nil
+}
+
+func (l *local) List(ctx context.Context, req *imagesapi.ListImagesRequest, _ ...grpc.CallOption) (*imagesapi.ListImagesResponse, error) {
+	images, err := l.store.List(ctx, req.Filters...)
+	if err != nil {
+		return nil, errdefs.ToGRPC(err)
+	}
+
+	return &imagesapi.ListImagesResponse{
+		Images: imagesToProto(images),
+	}, nil
+}
+
+func (l *local) Create(ctx context.Context, req *imagesapi.CreateImageRequest, _ ...grpc.CallOption) (*imagesapi.CreateImageResponse, error) {
+	log.G(ctx).WithField("name", req.Image.Name).WithField("target", req.Image.Target.Digest).Debugf("create image")
+	if req.Image.Name == "" {
+		return nil, status.Errorf(codes.InvalidArgument, "Image.Name required")
+	}
+
+	var (
+		image = imageFromProto(&req.Image)
+		resp  imagesapi.CreateImageResponse
+	)
+	created, err := l.store.Create(ctx, image)
+	if err != nil {
+		return nil, errdefs.ToGRPC(err)
+	}
+
+	resp.Image = imageToProto(&created)
+
+	if err := l.publisher.Publish(ctx, "/images/create", &eventstypes.ImageCreate{
+		Name:   resp.Image.Name,
+		Labels: resp.Image.Labels,
+	}); err != nil {
+		return nil, err
+	}
+
+	return &resp, nil
+
+}
+
+func (l *local) Update(ctx context.Context, req *imagesapi.UpdateImageRequest, _ ...grpc.CallOption) (*imagesapi.UpdateImageResponse, error) {
+	if req.Image.Name == "" {
+		return nil, status.Errorf(codes.InvalidArgument, "Image.Name required")
+	}
+
+	var (
+		image      = imageFromProto(&req.Image)
+		resp       imagesapi.UpdateImageResponse
+		fieldpaths []string
+	)
+
+	if req.UpdateMask != nil && len(req.UpdateMask.Paths) > 0 {
+		for _, path := range req.UpdateMask.Paths {
+			fieldpaths = append(fieldpaths, path)
+		}
+	}
+
+	updated, err := l.store.Update(ctx, image, fieldpaths...)
+	if err != nil {
+		return nil, errdefs.ToGRPC(err)
+	}
+
+	resp.Image = imageToProto(&updated)
+
+	if err := l.publisher.Publish(ctx, "/images/update", &eventstypes.ImageUpdate{
+		Name:   resp.Image.Name,
+		Labels: resp.Image.Labels,
+	}); err != nil {
+		return nil, err
+	}
+
+	return &resp, nil
+}
+
+func (l *local) Delete(ctx context.Context, req *imagesapi.DeleteImageRequest, _ ...grpc.CallOption) (*ptypes.Empty, error) {
+	log.G(ctx).WithField("name", req.Name).Debugf("delete image")
+
+	if err := l.store.Delete(ctx, req.Name); err != nil {
+		return nil, errdefs.ToGRPC(err)
+	}
+
+	if err := l.publisher.Publish(ctx, "/images/delete", &eventstypes.ImageDelete{
+		Name: req.Name,
+	}); err != nil {
+		return nil, err
+	}
+
+	if req.Sync {
+		if _, err := l.gc.ScheduleAndWait(ctx); err != nil {
+			return nil, err
+		}
+	}
+
+	return &ptypes.Empty{}, nil
+}

services/images/service.go

@@ -17,22 +17,13 @@
 package images
 
 import (
-	gocontext "context"
-
-	eventstypes "github.com/containerd/containerd/api/events"
 	imagesapi "github.com/containerd/containerd/api/services/images/v1"
-	"github.com/containerd/containerd/errdefs"
-	"github.com/containerd/containerd/events"
-	"github.com/containerd/containerd/gc"
-	"github.com/containerd/containerd/images"
-	"github.com/containerd/containerd/log"
-	"github.com/containerd/containerd/metadata"
 	"github.com/containerd/containerd/plugin"
+	"github.com/containerd/containerd/services"
 	ptypes "github.com/gogo/protobuf/types"
+	"github.com/pkg/errors"
 	"golang.org/x/net/context"
 	"google.golang.org/grpc"
-	"google.golang.org/grpc/codes"
-	"google.golang.org/grpc/status"
 )
 
 func init() {
@@ -40,42 +31,31 @@ func init() {
 		Type: plugin.GRPCPlugin,
 		ID:   "images",
 		Requires: []plugin.Type{
-			plugin.MetadataPlugin,
-			plugin.GCPlugin,
+			plugin.ServicePlugin,
 		},
 		InitFn: func(ic *plugin.InitContext) (interface{}, error) {
-			m, err := ic.Get(plugin.MetadataPlugin)
+			plugins, err := ic.GetByType(plugin.ServicePlugin)
 			if err != nil {
 				return nil, err
 			}
-			g, err := ic.Get(plugin.GCPlugin)
+			p, ok := plugins[services.ImagesService]
+			if !ok {
+				return nil, errors.New("images service not found")
+			}
+			i, err := p.Instance()
 			if err != nil {
 				return nil, err
 			}
-
-			return NewService(metadata.NewImageStore(m.(*metadata.DB)), ic.Events, g.(gcScheduler)), nil
+			return &service{local: i.(imagesapi.ImagesClient)}, nil
 		},
 	})
 }
 
-type gcScheduler interface {
-	ScheduleAndWait(gocontext.Context) (gc.Stats, error)
-}
-
 type service struct {
-	store     images.Store
-	gc        gcScheduler
-	publisher events.Publisher
+	local imagesapi.ImagesClient
 }
 
-// NewService returns the GRPC image server
-func NewService(is images.Store, publisher events.Publisher, gc gcScheduler) imagesapi.ImagesServer {
-	return &service{
-		store:     is,
-		gc:        gc,
-		publisher: publisher,
-	}
-}
+var _ imagesapi.ImagesServer = &service{}
 
 func (s *service) Register(server *grpc.Server) error {
 	imagesapi.RegisterImagesServer(server, s)
@@ -83,108 +63,21 @@ func (s *service) Register(server *grpc.Server) error {
 }
 
 func (s *service) Get(ctx context.Context, req *imagesapi.GetImageRequest) (*imagesapi.GetImageResponse, error) {
-	image, err := s.store.Get(ctx, req.Name)
-	if err != nil {
-		return nil, errdefs.ToGRPC(err)
-	}
-
-	imagepb := imageToProto(&image)
-	return &imagesapi.GetImageResponse{
-		Image: &imagepb,
-	}, nil
+	return s.local.Get(ctx, req)
 }
 
 func (s *service) List(ctx context.Context, req *imagesapi.ListImagesRequest) (*imagesapi.ListImagesResponse, error) {
-	images, err := s.store.List(ctx, req.Filters...)
-	if err != nil {
-		return nil, errdefs.ToGRPC(err)
-	}
-
-	return &imagesapi.ListImagesResponse{
-		Images: imagesToProto(images),
-	}, nil
+	return s.local.List(ctx, req)
 }
 
 func (s *service) Create(ctx context.Context, req *imagesapi.CreateImageRequest) (*imagesapi.CreateImageResponse, error) {
-	log.G(ctx).WithField("name", req.Image.Name).WithField("target", req.Image.Target.Digest).Debugf("create image")
-	if req.Image.Name == "" {
-		return nil, status.Errorf(codes.InvalidArgument, "Image.Name required")
-	}
-
-	var (
-		image = imageFromProto(&req.Image)
-		resp  imagesapi.CreateImageResponse
-	)
-	created, err := s.store.Create(ctx, image)
-	if err != nil {
-		return nil, errdefs.ToGRPC(err)
-	}
-
-	resp.Image = imageToProto(&created)
-
-	if err := s.publisher.Publish(ctx, "/images/create", &eventstypes.ImageCreate{
-		Name:   resp.Image.Name,
-		Labels: resp.Image.Labels,
-	}); err != nil {
-		return nil, err
-	}
-
-	return &resp, nil
-
+	return s.local.Create(ctx, req)
 }
 
 func (s *service) Update(ctx context.Context, req *imagesapi.UpdateImageRequest) (*imagesapi.UpdateImageResponse, error) {
-	if req.Image.Name == "" {
-		return nil, status.Errorf(codes.InvalidArgument, "Image.Name required")
-	}
-
-	var (
-		image      = imageFromProto(&req.Image)
-		resp       imagesapi.UpdateImageResponse
-		fieldpaths []string
-	)
-
-	if req.UpdateMask != nil && len(req.UpdateMask.Paths) > 0 {
-		for _, path := range req.UpdateMask.Paths {
-			fieldpaths = append(fieldpaths, path)
-		}
-	}
-
-	updated, err := s.store.Update(ctx, image, fieldpaths...)
-	if err != nil {
-		return nil, errdefs.ToGRPC(err)
-	}
-
-	resp.Image = imageToProto(&updated)
-
-	if err := s.publisher.Publish(ctx, "/images/update", &eventstypes.ImageUpdate{
-		Name:   resp.Image.Name,
-		Labels: resp.Image.Labels,
-	}); err != nil {
-		return nil, err
-	}
-
-	return &resp, nil
+	return s.local.Update(ctx, req)
 }
 
 func (s *service) Delete(ctx context.Context, req *imagesapi.DeleteImageRequest) (*ptypes.Empty, error) {
-	log.G(ctx).WithField("name", req.Name).Debugf("delete image")
-
-	if err := s.store.Delete(ctx, req.Name); err != nil {
-		return nil, errdefs.ToGRPC(err)
-	}
-
-	if err := s.publisher.Publish(ctx, "/images/delete", &eventstypes.ImageDelete{
-		Name: req.Name,
-	}); err != nil {
-		return nil, err
-	}
-
-	if req.Sync {
-		if _, err := s.gc.ScheduleAndWait(ctx); err != nil {
-			return nil, err
-		}
-	}
-
-	return &ptypes.Empty{}, nil
+	return s.local.Delete(ctx, req)
 }

services/leases/local.go

@@ -0,0 +1,120 @@
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package leases
+
+import (
+	"crypto/rand"
+	"encoding/base64"
+	"fmt"
+	"time"
+
+	"google.golang.org/grpc"
+
+	"github.com/boltdb/bolt"
+	api "github.com/containerd/containerd/api/services/leases/v1"
+	"github.com/containerd/containerd/metadata"
+	"github.com/containerd/containerd/plugin"
+	"github.com/containerd/containerd/services"
+	ptypes "github.com/gogo/protobuf/types"
+	"golang.org/x/net/context"
+)
+
+func init() {
+	plugin.Register(&plugin.Registration{
+		Type: plugin.ServicePlugin,
+		ID:   services.LeasesService,
+		Requires: []plugin.Type{
+			plugin.MetadataPlugin,
+		},
+		InitFn: func(ic *plugin.InitContext) (interface{}, error) {
+			m, err := ic.Get(plugin.MetadataPlugin)
+			if err != nil {
+				return nil, err
+			}
+			return &local{db: m.(*metadata.DB)}, nil
+		},
+	})
+}
+
+type local struct {
+	db *metadata.DB
+}
+
+func (l *local) Create(ctx context.Context, r *api.CreateRequest, _ ...grpc.CallOption) (*api.CreateResponse, error) {
+	lid := r.ID
+	if lid == "" {
+		lid = generateLeaseID()
+	}
+	var trans metadata.Lease
+	if err := l.db.Update(func(tx *bolt.Tx) error {
+		var err error
+		trans, err = metadata.NewLeaseManager(tx).Create(ctx, lid, r.Labels)
+		return err
+	}); err != nil {
+		return nil, err
+	}
+	return &api.CreateResponse{
+		Lease: txToGRPC(trans),
+	}, nil
+}
+
+func (l *local) Delete(ctx context.Context, r *api.DeleteRequest, _ ...grpc.CallOption) (*ptypes.Empty, error) {
+	if err := l.db.Update(func(tx *bolt.Tx) error {
+		return metadata.NewLeaseManager(tx).Delete(ctx, r.ID)
+	}); err != nil {
+		return nil, err
+	}
+	return &ptypes.Empty{}, nil
+}
+
+func (l *local) List(ctx context.Context, r *api.ListRequest, _ ...grpc.CallOption) (*api.ListResponse, error) {
+	var leases []metadata.Lease
+	if err := l.db.View(func(tx *bolt.Tx) error {
+		var err error
+		leases, err = metadata.NewLeaseManager(tx).List(ctx, false, r.Filters...)
+		return err
+	}); err != nil {
+		return nil, err
+	}
+
+	apileases := make([]*api.Lease, len(leases))
+	for i := range leases {
+		apileases[i] = txToGRPC(leases[i])
+	}
+
+	return &api.ListResponse{
+		Leases: apileases,
+	}, nil
+}
+
+func txToGRPC(tx metadata.Lease) *api.Lease {
+	return &api.Lease{
+		ID:        tx.ID,
+		Labels:    tx.Labels,
+		CreatedAt: tx.CreatedAt,
+		// TODO: Snapshots
+		// TODO: Content
+	}
+}
+
+func generateLeaseID() string {
+	t := time.Now()
+	var b [3]byte
+	// Ignore read failures, just decreases uniqueness
+	rand.Read(b[:])
+	return fmt.Sprintf("%d-%s", t.Nanosecond(), base64.URLEncoding.EncodeToString(b[:]))
+}

services/leases/service.go

@@ -17,18 +17,13 @@
 package leases
 
 import (
-	"crypto/rand"
-	"encoding/base64"
-	"fmt"
-	"time"
-
 	"google.golang.org/grpc"
 
-	"github.com/boltdb/bolt"
 	api "github.com/containerd/containerd/api/services/leases/v1"
-	"github.com/containerd/containerd/metadata"
 	"github.com/containerd/containerd/plugin"
+	"github.com/containerd/containerd/services"
 	ptypes "github.com/gogo/protobuf/types"
+	"github.com/pkg/errors"
 	"golang.org/x/net/context"
 )
 
@@ -37,27 +32,28 @@ func init() {
 		Type: plugin.GRPCPlugin,
 		ID:   "leases",
 		Requires: []plugin.Type{
-			plugin.MetadataPlugin,
+			plugin.ServicePlugin,
 		},
 		InitFn: func(ic *plugin.InitContext) (interface{}, error) {
-			m, err := ic.Get(plugin.MetadataPlugin)
+			plugins, err := ic.GetByType(plugin.ServicePlugin)
 			if err != nil {
 				return nil, err
 			}
-			return NewService(m.(*metadata.DB)), nil
+			p, ok := plugins[services.LeasesService]
+			if !ok {
+				return nil, errors.New("leases service not found")
+			}
+			i, err := p.Instance()
+			if err != nil {
+				return nil, err
+			}
+			return &service{local: i.(api.LeasesClient)}, nil
 		},
 	})
 }
 
 type service struct {
-	db *metadata.DB
-}
-
-// NewService returns the GRPC metadata server
-func NewService(db *metadata.DB) api.LeasesServer {
-	return &service{
-		db: db,
-	}
+	local api.LeasesClient
 }
 
 func (s *service) Register(server *grpc.Server) error {
@@ -66,66 +62,13 @@ func (s *service) Register(server *grpc.Server) error {
 }
 
 func (s *service) Create(ctx context.Context, r *api.CreateRequest) (*api.CreateResponse, error) {
-	lid := r.ID
-	if lid == "" {
-		lid = generateLeaseID()
-	}
-	var trans metadata.Lease
-	if err := s.db.Update(func(tx *bolt.Tx) error {
-		var err error
-		trans, err = metadata.NewLeaseManager(tx).Create(ctx, lid, r.Labels)
-		return err
-	}); err != nil {
-		return nil, err
-	}
-	return &api.CreateResponse{
-		Lease: txToGRPC(trans),
-	}, nil
+	return s.local.Create(ctx, r)
 }
 
 func (s *service) Delete(ctx context.Context, r *api.DeleteRequest) (*ptypes.Empty, error) {
-	if err := s.db.Update(func(tx *bolt.Tx) error {
-		return metadata.NewLeaseManager(tx).Delete(ctx, r.ID)
-	}); err != nil {
-		return nil, err
-	}
-	return &ptypes.Empty{}, nil
+	return s.local.Delete(ctx, r)
 }
 
 func (s *service) List(ctx context.Context, r *api.ListRequest) (*api.ListResponse, error) {
-	var leases []metadata.Lease
-	if err := s.db.View(func(tx *bolt.Tx) error {
-		var err error
-		leases, err = metadata.NewLeaseManager(tx).List(ctx, false, r.Filters...)
-		return err
-	}); err != nil {
-		return nil, err
-	}
-
-	apileases := make([]*api.Lease, len(leases))
-	for i := range leases {
-		apileases[i] = txToGRPC(leases[i])
-	}
-
-	return &api.ListResponse{
-		Leases: apileases,
-	}, nil
-}
-
-func txToGRPC(tx metadata.Lease) *api.Lease {
-	return &api.Lease{
-		ID:        tx.ID,
-		Labels:    tx.Labels,
-		CreatedAt: tx.CreatedAt,
-		// TODO: Snapshots
-		// TODO: Content
-	}
-}
-
-func generateLeaseID() string {
-	t := time.Now()
-	var b [3]byte
-	// Ignore read failures, just decreases uniqueness
-	rand.Read(b[:])
-	return fmt.Sprintf("%d-%s", t.Nanosecond(), base64.URLEncoding.EncodeToString(b[:]))
+	return s.local.List(ctx, r)
 }

services/namespaces/local.go

@@ -0,0 +1,223 @@
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package namespaces
+
+import (
+	"strings"
+
+	"github.com/boltdb/bolt"
+	eventstypes "github.com/containerd/containerd/api/events"
+	api "github.com/containerd/containerd/api/services/namespaces/v1"
+	"github.com/containerd/containerd/errdefs"
+	"github.com/containerd/containerd/events"
+	"github.com/containerd/containerd/metadata"
+	"github.com/containerd/containerd/namespaces"
+	"github.com/containerd/containerd/plugin"
+	"github.com/containerd/containerd/services"
+	ptypes "github.com/gogo/protobuf/types"
+	"golang.org/x/net/context"
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/status"
+)
+
+func init() {
+	plugin.Register(&plugin.Registration{
+		Type: plugin.ServicePlugin,
+		ID:   services.NamespacesService,
+		Requires: []plugin.Type{
+			plugin.MetadataPlugin,
+		},
+		InitFn: func(ic *plugin.InitContext) (interface{}, error) {
+			m, err := ic.Get(plugin.MetadataPlugin)
+			if err != nil {
+				return nil, err
+			}
+			return &local{
+				db:        m.(*metadata.DB),
+				publisher: ic.Events,
+			}, nil
+		},
+	})
+}
+
+// Provide local namespaces service instead of local namespace store,
+// because namespace store interface doesn't provide enough functionality
+// for namespaces service.
+type local struct {
+	db        *metadata.DB
+	publisher events.Publisher
+}
+
+var _ api.NamespacesClient = &local{}
+
+func (l *local) Get(ctx context.Context, req *api.GetNamespaceRequest, _ ...grpc.CallOption) (*api.GetNamespaceResponse, error) {
+	var resp api.GetNamespaceResponse
+
+	return &resp, l.withStoreView(ctx, func(ctx context.Context, store namespaces.Store) error {
+		labels, err := store.Labels(ctx, req.Name)
+		if err != nil {
+			return errdefs.ToGRPC(err)
+		}
+
+		resp.Namespace = api.Namespace{
+			Name:   req.Name,
+			Labels: labels,
+		}
+
+		return nil
+	})
+}
+
+func (l *local) List(ctx context.Context, req *api.ListNamespacesRequest, _ ...grpc.CallOption) (*api.ListNamespacesResponse, error) {
+	var resp api.ListNamespacesResponse
+
+	return &resp, l.withStoreView(ctx, func(ctx context.Context, store namespaces.Store) error {
+		namespaces, err := store.List(ctx)
+		if err != nil {
+			return err
+		}
+
+		for _, namespace := range namespaces {
+			labels, err := store.Labels(ctx, namespace)
+			if err != nil {
+				// In general, this should be unlikely, since we are holding a
+				// transaction to service this request.
+				return errdefs.ToGRPC(err)
+			}
+
+			resp.Namespaces = append(resp.Namespaces, api.Namespace{
+				Name:   namespace,
+				Labels: labels,
+			})
+		}
+
+		return nil
+	})
+}
+
+func (l *local) Create(ctx context.Context, req *api.CreateNamespaceRequest, _ ...grpc.CallOption) (*api.CreateNamespaceResponse, error) {
+	var resp api.CreateNamespaceResponse
+
+	if err := l.withStoreUpdate(ctx, func(ctx context.Context, store namespaces.Store) error {
+		if err := store.Create(ctx, req.Namespace.Name, req.Namespace.Labels); err != nil {
+			return errdefs.ToGRPC(err)
+		}
+
+		for k, v := range req.Namespace.Labels {
+			if err := store.SetLabel(ctx, req.Namespace.Name, k, v); err != nil {
+				return err
+			}
+		}
+
+		resp.Namespace = req.Namespace
+		return nil
+	}); err != nil {
+		return &resp, err
+	}
+
+	if err := l.publisher.Publish(ctx, "/namespaces/create", &eventstypes.NamespaceCreate{
+		Name:   req.Namespace.Name,
+		Labels: req.Namespace.Labels,
+	}); err != nil {
+		return &resp, err
+	}
+
+	return &resp, nil
+
+}
+
+func (l *local) Update(ctx context.Context, req *api.UpdateNamespaceRequest, _ ...grpc.CallOption) (*api.UpdateNamespaceResponse, error) {
+	var resp api.UpdateNamespaceResponse
+	if err := l.withStoreUpdate(ctx, func(ctx context.Context, store namespaces.Store) error {
+		if req.UpdateMask != nil && len(req.UpdateMask.Paths) > 0 {
+			for _, path := range req.UpdateMask.Paths {
+				switch {
+				case strings.HasPrefix(path, "labels."):
+					key := strings.TrimPrefix(path, "labels.")
+					if err := store.SetLabel(ctx, req.Namespace.Name, key, req.Namespace.Labels[key]); err != nil {
+						return err
+					}
+				default:
+					return status.Errorf(codes.InvalidArgument, "cannot update %q field", path)
+				}
+			}
+		} else {
+			// clear out the existing labels and then set them to the incoming request.
+			// get current set of labels
+			labels, err := store.Labels(ctx, req.Namespace.Name)
+			if err != nil {
+				return errdefs.ToGRPC(err)
+			}
+
+			for k := range labels {
+				if err := store.SetLabel(ctx, req.Namespace.Name, k, ""); err != nil {
+					return err
+				}
+			}
+
+			for k, v := range req.Namespace.Labels {
+				if err := store.SetLabel(ctx, req.Namespace.Name, k, v); err != nil {
+					return err
+				}
+
+			}
+		}
+
+		return nil
+	}); err != nil {
+		return &resp, err
+	}
+
+	if err := l.publisher.Publish(ctx, "/namespaces/update", &eventstypes.NamespaceUpdate{
+		Name:   req.Namespace.Name,
+		Labels: req.Namespace.Labels,
+	}); err != nil {
+		return &resp, err
+	}
+
+	return &resp, nil
+}
+
+func (l *local) Delete(ctx context.Context, req *api.DeleteNamespaceRequest, _ ...grpc.CallOption) (*ptypes.Empty, error) {
+	if err := l.withStoreUpdate(ctx, func(ctx context.Context, store namespaces.Store) error {
+		return errdefs.ToGRPC(store.Delete(ctx, req.Name))
+	}); err != nil {
+		return &ptypes.Empty{}, err
+	}
+	// set the namespace in the context before publishing the event
+	ctx = namespaces.WithNamespace(ctx, req.Name)
+	if err := l.publisher.Publish(ctx, "/namespaces/delete", &eventstypes.NamespaceDelete{
+		Name: req.Name,
+	}); err != nil {
+		return &ptypes.Empty{}, err
+	}
+
+	return &ptypes.Empty{}, nil
+}
+
+func (l *local) withStore(ctx context.Context, fn func(ctx context.Context, store namespaces.Store) error) func(tx *bolt.Tx) error {
+	return func(tx *bolt.Tx) error { return fn(ctx, metadata.NewNamespaceStore(tx)) }
+}
+
+func (l *local) withStoreView(ctx context.Context, fn func(ctx context.Context, store namespaces.Store) error) error {
+	return l.db.View(l.withStore(ctx, fn))
+}
+
+func (l *local) withStoreUpdate(ctx context.Context, fn func(ctx context.Context, store namespaces.Store) error) error {
+	return l.db.Update(l.withStore(ctx, fn))
+}

services/namespaces/service.go

@@ -17,21 +17,13 @@
 package namespaces
 
 import (
-	"strings"
-
-	"github.com/boltdb/bolt"
-	eventstypes "github.com/containerd/containerd/api/events"
 	api "github.com/containerd/containerd/api/services/namespaces/v1"
-	"github.com/containerd/containerd/errdefs"
-	"github.com/containerd/containerd/events"
-	"github.com/containerd/containerd/metadata"
-	"github.com/containerd/containerd/namespaces"
 	"github.com/containerd/containerd/plugin"
+	"github.com/containerd/containerd/services"
 	ptypes "github.com/gogo/protobuf/types"
+	"github.com/pkg/errors"
 	"golang.org/x/net/context"
 	"google.golang.org/grpc"
-	"google.golang.org/grpc/codes"
-	"google.golang.org/grpc/status"
 )
 
 func init() {
@@ -39,191 +31,53 @@ func init() {
 		Type: plugin.GRPCPlugin,
 		ID:   "namespaces",
 		Requires: []plugin.Type{
-			plugin.MetadataPlugin,
+			plugin.ServicePlugin,
 		},
 		InitFn: func(ic *plugin.InitContext) (interface{}, error) {
-			m, err := ic.Get(plugin.MetadataPlugin)
+			plugins, err := ic.GetByType(plugin.ServicePlugin)
 			if err != nil {
 				return nil, err
 			}
-			return NewService(m.(*metadata.DB), ic.Events), nil
+			p, ok := plugins[services.NamespacesService]
+			if !ok {
+				return nil, errors.New("namespaces service not found")
+			}
+			i, err := p.Instance()
+			if err != nil {
+				return nil, err
+			}
+			return &service{local: i.(api.NamespacesClient)}, nil
 		},
 	})
 }
 
 type service struct {
-	db        *metadata.DB
-	publisher events.Publisher
+	local api.NamespacesClient
 }
 
 var _ api.NamespacesServer = &service{}
 
-// NewService returns the GRPC namespaces server
-func NewService(db *metadata.DB, publisher events.Publisher) api.NamespacesServer {
-	return &service{
-		db:        db,
-		publisher: publisher,
-	}
-}
-
 func (s *service) Register(server *grpc.Server) error {
 	api.RegisterNamespacesServer(server, s)
 	return nil
 }
 
 func (s *service) Get(ctx context.Context, req *api.GetNamespaceRequest) (*api.GetNamespaceResponse, error) {
-	var resp api.GetNamespaceResponse
-
-	return &resp, s.withStoreView(ctx, func(ctx context.Context, store namespaces.Store) error {
-		labels, err := store.Labels(ctx, req.Name)
-		if err != nil {
-			return errdefs.ToGRPC(err)
-		}
-
-		resp.Namespace = api.Namespace{
-			Name:   req.Name,
-			Labels: labels,
-		}
-
-		return nil
-	})
+	return s.local.Get(ctx, req)
 }
 
 func (s *service) List(ctx context.Context, req *api.ListNamespacesRequest) (*api.ListNamespacesResponse, error) {
-	var resp api.ListNamespacesResponse
-
-	return &resp, s.withStoreView(ctx, func(ctx context.Context, store namespaces.Store) error {
-		namespaces, err := store.List(ctx)
-		if err != nil {
-			return err
-		}
-
-		for _, namespace := range namespaces {
-			labels, err := store.Labels(ctx, namespace)
-			if err != nil {
-				// In general, this should be unlikely, since we are holding a
-				// transaction to service this request.
-				return errdefs.ToGRPC(err)
-			}
-
-			resp.Namespaces = append(resp.Namespaces, api.Namespace{
-				Name:   namespace,
-				Labels: labels,
-			})
-		}
-
-		return nil
-	})
+	return s.local.List(ctx, req)
 }
 
 func (s *service) Create(ctx context.Context, req *api.CreateNamespaceRequest) (*api.CreateNamespaceResponse, error) {
-	var resp api.CreateNamespaceResponse
-
-	if err := s.withStoreUpdate(ctx, func(ctx context.Context, store namespaces.Store) error {
-		if err := store.Create(ctx, req.Namespace.Name, req.Namespace.Labels); err != nil {
-			return errdefs.ToGRPC(err)
-		}
-
-		for k, v := range req.Namespace.Labels {
-			if err := store.SetLabel(ctx, req.Namespace.Name, k, v); err != nil {
-				return err
-			}
-		}
-
-		resp.Namespace = req.Namespace
-		return nil
-	}); err != nil {
-		return &resp, err
-	}
-
-	if err := s.publisher.Publish(ctx, "/namespaces/create", &eventstypes.NamespaceCreate{
-		Name:   req.Namespace.Name,
-		Labels: req.Namespace.Labels,
-	}); err != nil {
-		return &resp, err
-	}
-
-	return &resp, nil
-
+	return s.local.Create(ctx, req)
 }
 
 func (s *service) Update(ctx context.Context, req *api.UpdateNamespaceRequest) (*api.UpdateNamespaceResponse, error) {
-	var resp api.UpdateNamespaceResponse
-	if err := s.withStoreUpdate(ctx, func(ctx context.Context, store namespaces.Store) error {
-		if req.UpdateMask != nil && len(req.UpdateMask.Paths) > 0 {
-			for _, path := range req.UpdateMask.Paths {
-				switch {
-				case strings.HasPrefix(path, "labels."):
-					key := strings.TrimPrefix(path, "labels.")
-					if err := store.SetLabel(ctx, req.Namespace.Name, key, req.Namespace.Labels[key]); err != nil {
-						return err
-					}
-				default:
-					return status.Errorf(codes.InvalidArgument, "cannot update %q field", path)
-				}
-			}
-		} else {
-			// clear out the existing labels and then set them to the incoming request.
-			// get current set of labels
-			labels, err := store.Labels(ctx, req.Namespace.Name)
-			if err != nil {
-				return errdefs.ToGRPC(err)
-			}
-
-			for k := range labels {
-				if err := store.SetLabel(ctx, req.Namespace.Name, k, ""); err != nil {
-					return err
-				}
-			}
-
-			for k, v := range req.Namespace.Labels {
-				if err := store.SetLabel(ctx, req.Namespace.Name, k, v); err != nil {
-					return err
-				}
-
-			}
-		}
-
-		return nil
-	}); err != nil {
-		return &resp, err
-	}
-
-	if err := s.publisher.Publish(ctx, "/namespaces/update", &eventstypes.NamespaceUpdate{
-		Name:   req.Namespace.Name,
-		Labels: req.Namespace.Labels,
-	}); err != nil {
-		return &resp, err
-	}
-
-	return &resp, nil
+	return s.local.Update(ctx, req)
 }
 
 func (s *service) Delete(ctx context.Context, req *api.DeleteNamespaceRequest) (*ptypes.Empty, error) {
-	if err := s.withStoreUpdate(ctx, func(ctx context.Context, store namespaces.Store) error {
-		return errdefs.ToGRPC(store.Delete(ctx, req.Name))
-	}); err != nil {
-		return &ptypes.Empty{}, err
-	}
-	// set the namespace in the context before publishing the event
-	ctx = namespaces.WithNamespace(ctx, req.Name)
-	if err := s.publisher.Publish(ctx, "/namespaces/delete", &eventstypes.NamespaceDelete{
-		Name: req.Name,
-	}); err != nil {
-		return &ptypes.Empty{}, err
-	}
-
-	return &ptypes.Empty{}, nil
-}
-
-func (s *service) withStore(ctx context.Context, fn func(ctx context.Context, store namespaces.Store) error) func(tx *bolt.Tx) error {
-	return func(tx *bolt.Tx) error { return fn(ctx, metadata.NewNamespaceStore(tx)) }
-}
-
-func (s *service) withStoreView(ctx context.Context, fn func(ctx context.Context, store namespaces.Store) error) error {
-	return s.db.View(s.withStore(ctx, fn))
-}
-
-func (s *service) withStoreUpdate(ctx context.Context, fn func(ctx context.Context, store namespaces.Store) error) error {
-	return s.db.Update(s.withStore(ctx, fn))
+	return s.local.Delete(ctx, req)
 }

services/services.go

@@ -0,0 +1,36 @@
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package services
+
+const (
+	// ContentService is id of content service.
+	ContentService = "content-service"
+	// SnapshotsService is id of snapshots service.
+	SnapshotsService = "snapshots-service"
+	// ImagesService is id of images service.
+	ImagesService = "images-service"
+	// ContainersService is id of containers service.
+	ContainersService = "containers-service"
+	// TasksService is id of tasks service.
+	TasksService = "tasks-service"
+	// NamespacesService is id of namespaces service.
+	NamespacesService = "namespaces-service"
+	// LeasesService is id of leases service.
+	LeasesService = "leases-service"
+	// DiffService is id of diff service.
+	DiffService = "diff-service"
+)

services/snapshots/service.go

@@ -19,17 +19,16 @@ package snapshots
 import (
 	gocontext "context"
 
-	eventstypes "github.com/containerd/containerd/api/events"
 	snapshotsapi "github.com/containerd/containerd/api/services/snapshots/v1"
 	"github.com/containerd/containerd/api/types"
 	"github.com/containerd/containerd/errdefs"
-	"github.com/containerd/containerd/events"
 	"github.com/containerd/containerd/log"
-	"github.com/containerd/containerd/metadata"
 	"github.com/containerd/containerd/mount"
 	"github.com/containerd/containerd/plugin"
+	"github.com/containerd/containerd/services"
 	"github.com/containerd/containerd/snapshots"
 	ptypes "github.com/gogo/protobuf/types"
+	"github.com/pkg/errors"
 	"golang.org/x/net/context"
 	"google.golang.org/grpc"
 )
@@ -39,7 +38,7 @@ func init() {
 		Type: plugin.GRPCPlugin,
 		ID:   "snapshots",
 		Requires: []plugin.Type{
-			plugin.MetadataPlugin,
+			plugin.ServicePlugin,
 		},
 		InitFn: newService,
 	})
@@ -48,20 +47,24 @@ func init() {
 var empty = &ptypes.Empty{}
 
 type service struct {
-	db        *metadata.DB
-	publisher events.Publisher
+	ss map[string]snapshots.Snapshotter
 }
 
 func newService(ic *plugin.InitContext) (interface{}, error) {
-	md, err := ic.Get(plugin.MetadataPlugin)
+	plugins, err := ic.GetByType(plugin.ServicePlugin)
 	if err != nil {
 		return nil, err
 	}
-
-	return &service{
-		db:        md.(*metadata.DB),
-		publisher: ic.Events,
-	}, nil
+	p, ok := plugins[services.SnapshotsService]
+	if !ok {
+		return nil, errors.New("snapshots service not found")
+	}
+	i, err := p.Instance()
+	if err != nil {
+		return nil, err
+	}
+	ss := i.(map[string]snapshots.Snapshotter)
+	return &service{ss: ss}, nil
 }
 
 func (s *service) getSnapshotter(name string) (snapshots.Snapshotter, error) {
@@ -69,7 +72,7 @@ func (s *service) getSnapshotter(name string) (snapshots.Snapshotter, error) {
 		return nil, errdefs.ToGRPCf(errdefs.ErrInvalidArgument, "snapshotter argument missing")
 	}
 
-	sn := s.db.Snapshotter(name)
+	sn := s.ss[name]
 	if sn == nil {
 		return nil, errdefs.ToGRPCf(errdefs.ErrInvalidArgument, "snapshotter not loaded: %s", name)
 	}
@@ -97,12 +100,6 @@ func (s *service) Prepare(ctx context.Context, pr *snapshotsapi.PrepareSnapshotR
 		return nil, errdefs.ToGRPC(err)
 	}
 
-	if err := s.publisher.Publish(ctx, "/snapshot/prepare", &eventstypes.SnapshotPrepare{
-		Key:    pr.Key,
-		Parent: pr.Parent,
-	}); err != nil {
-		return nil, err
-	}
 	return &snapshotsapi.PrepareSnapshotResponse{
 		Mounts: fromMounts(mounts),
 	}, nil
@@ -158,12 +155,6 @@ func (s *service) Commit(ctx context.Context, cr *snapshotsapi.CommitSnapshotReq
 		return nil, errdefs.ToGRPC(err)
 	}
 
-	if err := s.publisher.Publish(ctx, "/snapshot/commit", &eventstypes.SnapshotCommit{
-		Key:  cr.Key,
-		Name: cr.Name,
-	}); err != nil {
-		return nil, err
-	}
 	return empty, nil
 }
 
@@ -178,11 +169,6 @@ func (s *service) Remove(ctx context.Context, rr *snapshotsapi.RemoveSnapshotReq
 		return nil, errdefs.ToGRPC(err)
 	}
 
-	if err := s.publisher.Publish(ctx, "/snapshot/remove", &eventstypes.SnapshotRemove{
-		Key: rr.Key,
-	}); err != nil {
-		return nil, err
-	}
 	return empty, nil
 }
 

services/snapshots/snapshotters.go

@@ -0,0 +1,98 @@
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package snapshots
+
+import (
+	"context"
+
+	eventstypes "github.com/containerd/containerd/api/events"
+	"github.com/containerd/containerd/events"
+	"github.com/containerd/containerd/metadata"
+	"github.com/containerd/containerd/mount"
+	"github.com/containerd/containerd/plugin"
+	"github.com/containerd/containerd/services"
+	"github.com/containerd/containerd/snapshots"
+)
+
+// snapshotter wraps snapshots.Snapshotter with proper events published.
+type snapshotter struct {
+	snapshots.Snapshotter
+	publisher events.Publisher
+}
+
+func init() {
+	plugin.Register(&plugin.Registration{
+		Type: plugin.ServicePlugin,
+		ID:   services.SnapshotsService,
+		Requires: []plugin.Type{
+			plugin.MetadataPlugin,
+		},
+		InitFn: func(ic *plugin.InitContext) (interface{}, error) {
+			m, err := ic.Get(plugin.MetadataPlugin)
+			if err != nil {
+				return nil, err
+			}
+
+			db := m.(*metadata.DB)
+			ss := make(map[string]snapshots.Snapshotter)
+			for n, sn := range db.Snapshotters() {
+				ss[n] = newSnapshotter(sn, ic.Events)
+			}
+			return ss, nil
+		},
+	})
+}
+
+func newSnapshotter(sn snapshots.Snapshotter, publisher events.Publisher) snapshots.Snapshotter {
+	return &snapshotter{
+		Snapshotter: sn,
+		publisher:   publisher,
+	}
+}
+
+func (s *snapshotter) Prepare(ctx context.Context, key, parent string, opts ...snapshots.Opt) ([]mount.Mount, error) {
+	mounts, err := s.Snapshotter.Prepare(ctx, key, parent, opts...)
+	if err != nil {
+		return nil, err
+	}
+	if err := s.publisher.Publish(ctx, "/snapshot/prepare", &eventstypes.SnapshotPrepare{
+		Key:    key,
+		Parent: parent,
+	}); err != nil {
+		return nil, err
+	}
+	return mounts, nil
+}
+
+func (s *snapshotter) Commit(ctx context.Context, name, key string, opts ...snapshots.Opt) error {
+	if err := s.Snapshotter.Commit(ctx, name, key, opts...); err != nil {
+		return err
+	}
+	return s.publisher.Publish(ctx, "/snapshot/commit", &eventstypes.SnapshotCommit{
+		Key:  key,
+		Name: name,
+	})
+}
+
+func (s *snapshotter) Remove(ctx context.Context, key string) error {
+	if err := s.Snapshotter.Remove(ctx, key); err != nil {
+		return err
+	}
+	return s.publisher.Publish(ctx, "/snapshot/remove", &eventstypes.SnapshotRemove{
+		Key: key,
+	})
+}

services/tasks/local.go

@@ -0,0 +1,634 @@
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package tasks
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"time"
+
+	"github.com/boltdb/bolt"
+	api "github.com/containerd/containerd/api/services/tasks/v1"
+	"github.com/containerd/containerd/api/types"
+	"github.com/containerd/containerd/api/types/task"
+	"github.com/containerd/containerd/archive"
+	"github.com/containerd/containerd/containers"
+	"github.com/containerd/containerd/content"
+	"github.com/containerd/containerd/errdefs"
+	"github.com/containerd/containerd/events"
+	"github.com/containerd/containerd/filters"
+	"github.com/containerd/containerd/images"
+	"github.com/containerd/containerd/log"
+	"github.com/containerd/containerd/metadata"
+	"github.com/containerd/containerd/mount"
+	"github.com/containerd/containerd/plugin"
+	"github.com/containerd/containerd/runtime"
+	"github.com/containerd/containerd/services"
+	"github.com/containerd/typeurl"
+	ptypes "github.com/gogo/protobuf/types"
+	"github.com/pkg/errors"
+	"golang.org/x/net/context"
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/status"
+)
+
+var (
+	_     = (api.TasksClient)(&local{})
+	empty = &ptypes.Empty{}
+)
+
+func init() {
+	plugin.Register(&plugin.Registration{
+		Type: plugin.ServicePlugin,
+		ID:   services.TasksService,
+		Requires: []plugin.Type{
+			plugin.RuntimePlugin,
+			plugin.MetadataPlugin,
+		},
+		InitFn: initFunc,
+	})
+}
+
+func initFunc(ic *plugin.InitContext) (interface{}, error) {
+	rt, err := ic.GetByType(plugin.RuntimePlugin)
+	if err != nil {
+		return nil, err
+	}
+
+	m, err := ic.Get(plugin.MetadataPlugin)
+	if err != nil {
+		return nil, err
+	}
+	cs := m.(*metadata.DB).ContentStore()
+	runtimes := make(map[string]runtime.Runtime)
+	for _, rr := range rt {
+		ri, err := rr.Instance()
+		if err != nil {
+			log.G(ic.Context).WithError(err).Warn("could not load runtime instance due to initialization error")
+			continue
+		}
+		r := ri.(runtime.Runtime)
+		runtimes[r.ID()] = r
+	}
+
+	if len(runtimes) == 0 {
+		return nil, errors.New("no runtimes available to create task service")
+	}
+	return &local{
+		runtimes:  runtimes,
+		db:        m.(*metadata.DB),
+		store:     cs,
+		publisher: ic.Events,
+	}, nil
+}
+
+type local struct {
+	runtimes  map[string]runtime.Runtime
+	db        *metadata.DB
+	store     content.Store
+	publisher events.Publisher
+}
+
+func (l *local) Create(ctx context.Context, r *api.CreateTaskRequest, _ ...grpc.CallOption) (*api.CreateTaskResponse, error) {
+	var (
+		checkpointPath string
+		err            error
+	)
+	if r.Checkpoint != nil {
+		checkpointPath, err = ioutil.TempDir("", "ctrd-checkpoint")
+		if err != nil {
+			return nil, err
+		}
+		if r.Checkpoint.MediaType != images.MediaTypeContainerd1Checkpoint {
+			return nil, fmt.Errorf("unsupported checkpoint type %q", r.Checkpoint.MediaType)
+		}
+		reader, err := l.store.ReaderAt(ctx, r.Checkpoint.Digest)
+		if err != nil {
+			return nil, err
+		}
+		_, err = archive.Apply(ctx, checkpointPath, content.NewReader(reader))
+		reader.Close()
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	container, err := l.getContainer(ctx, r.ContainerID)
+	if err != nil {
+		return nil, errdefs.ToGRPC(err)
+	}
+	opts := runtime.CreateOpts{
+		Spec: container.Spec,
+		IO: runtime.IO{
+			Stdin:    r.Stdin,
+			Stdout:   r.Stdout,
+			Stderr:   r.Stderr,
+			Terminal: r.Terminal,
+		},
+		Checkpoint: checkpointPath,
+		Options:    r.Options,
+	}
+	for _, m := range r.Rootfs {
+		opts.Rootfs = append(opts.Rootfs, mount.Mount{
+			Type:    m.Type,
+			Source:  m.Source,
+			Options: m.Options,
+		})
+	}
+	runtime, err := l.getRuntime(container.Runtime.Name)
+	if err != nil {
+		return nil, err
+	}
+	c, err := runtime.Create(ctx, r.ContainerID, opts)
+	if err != nil {
+		return nil, errdefs.ToGRPC(err)
+	}
+	state, err := c.State(ctx)
+	if err != nil {
+		log.G(ctx).Error(err)
+	}
+
+	return &api.CreateTaskResponse{
+		ContainerID: r.ContainerID,
+		Pid:         state.Pid,
+	}, nil
+}
+
+func (l *local) Start(ctx context.Context, r *api.StartRequest, _ ...grpc.CallOption) (*api.StartResponse, error) {
+	t, err := l.getTask(ctx, r.ContainerID)
+	if err != nil {
+		return nil, err
+	}
+	p := runtime.Process(t)
+	if r.ExecID != "" {
+		if p, err = t.Process(ctx, r.ExecID); err != nil {
+			return nil, errdefs.ToGRPC(err)
+		}
+	}
+	if err := p.Start(ctx); err != nil {
+		return nil, errdefs.ToGRPC(err)
+	}
+	state, err := p.State(ctx)
+	if err != nil {
+		return nil, errdefs.ToGRPC(err)
+	}
+	return &api.StartResponse{
+		Pid: state.Pid,
+	}, nil
+}
+
+func (l *local) Delete(ctx context.Context, r *api.DeleteTaskRequest, _ ...grpc.CallOption) (*api.DeleteResponse, error) {
+	t, err := l.getTask(ctx, r.ContainerID)
+	if err != nil {
+		return nil, err
+	}
+	runtime, err := l.getRuntime(t.Info().Runtime)
+	if err != nil {
+		return nil, err
+	}
+	exit, err := runtime.Delete(ctx, t)
+	if err != nil {
+		return nil, errdefs.ToGRPC(err)
+	}
+	return &api.DeleteResponse{
+		ExitStatus: exit.Status,
+		ExitedAt:   exit.Timestamp,
+		Pid:        exit.Pid,
+	}, nil
+}
+
+func (l *local) DeleteProcess(ctx context.Context, r *api.DeleteProcessRequest, _ ...grpc.CallOption) (*api.DeleteResponse, error) {
+	t, err := l.getTask(ctx, r.ContainerID)
+	if err != nil {
+		return nil, err
+	}
+	exit, err := t.DeleteProcess(ctx, r.ExecID)
+	if err != nil {
+		return nil, errdefs.ToGRPC(err)
+	}
+	return &api.DeleteResponse{
+		ID:         r.ExecID,
+		ExitStatus: exit.Status,
+		ExitedAt:   exit.Timestamp,
+		Pid:        exit.Pid,
+	}, nil
+}
+
+func processFromContainerd(ctx context.Context, p runtime.Process) (*task.Process, error) {
+	state, err := p.State(ctx)
+	if err != nil {
+		return nil, err
+	}
+	var status task.Status
+	switch state.Status {
+	case runtime.CreatedStatus:
+		status = task.StatusCreated
+	case runtime.RunningStatus:
+		status = task.StatusRunning
+	case runtime.StoppedStatus:
+		status = task.StatusStopped
+	case runtime.PausedStatus:
+		status = task.StatusPaused
+	case runtime.PausingStatus:
+		status = task.StatusPausing
+	default:
+		log.G(ctx).WithField("status", state.Status).Warn("unknown status")
+	}
+	return &task.Process{
+		ID:         p.ID(),
+		Pid:        state.Pid,
+		Status:     status,
+		Stdin:      state.Stdin,
+		Stdout:     state.Stdout,
+		Stderr:     state.Stderr,
+		Terminal:   state.Terminal,
+		ExitStatus: state.ExitStatus,
+		ExitedAt:   state.ExitedAt,
+	}, nil
+}
+
+func (l *local) Get(ctx context.Context, r *api.GetRequest, _ ...grpc.CallOption) (*api.GetResponse, error) {
+	task, err := l.getTask(ctx, r.ContainerID)
+	if err != nil {
+		return nil, err
+	}
+	p := runtime.Process(task)
+	if r.ExecID != "" {
+		if p, err = task.Process(ctx, r.ExecID); err != nil {
+			return nil, errdefs.ToGRPC(err)
+		}
+	}
+	t, err := processFromContainerd(ctx, p)
+	if err != nil {
+		return nil, errdefs.ToGRPC(err)
+	}
+	return &api.GetResponse{
+		Process: t,
+	}, nil
+}
+
+func (l *local) List(ctx context.Context, r *api.ListTasksRequest, _ ...grpc.CallOption) (*api.ListTasksResponse, error) {
+	resp := &api.ListTasksResponse{}
+	for _, r := range l.runtimes {
+		tasks, err := r.Tasks(ctx)
+		if err != nil {
+			return nil, errdefs.ToGRPC(err)
+		}
+		addTasks(ctx, resp, tasks)
+	}
+	return resp, nil
+}
+
+func addTasks(ctx context.Context, r *api.ListTasksResponse, tasks []runtime.Task) {
+	for _, t := range tasks {
+		tt, err := processFromContainerd(ctx, t)
+		if err != nil {
+			if !errdefs.IsNotFound(err) { // handle race with deletion
+				log.G(ctx).WithError(err).WithField("id", t.ID()).Error("converting task to protobuf")
+			}
+			continue
+		}
+		r.Tasks = append(r.Tasks, tt)
+	}
+}
+
+func (l *local) Pause(ctx context.Context, r *api.PauseTaskRequest, _ ...grpc.CallOption) (*ptypes.Empty, error) {
+	t, err := l.getTask(ctx, r.ContainerID)
+	if err != nil {
+		return nil, err
+	}
+	err = t.Pause(ctx)
+	if err != nil {
+		return nil, errdefs.ToGRPC(err)
+	}
+	return empty, nil
+}
+
+func (l *local) Resume(ctx context.Context, r *api.ResumeTaskRequest, _ ...grpc.CallOption) (*ptypes.Empty, error) {
+	t, err := l.getTask(ctx, r.ContainerID)
+	if err != nil {
+		return nil, err
+	}
+	err = t.Resume(ctx)
+	if err != nil {
+		return nil, errdefs.ToGRPC(err)
+	}
+	return empty, nil
+}
+
+func (l *local) Kill(ctx context.Context, r *api.KillRequest, _ ...grpc.CallOption) (*ptypes.Empty, error) {
+	t, err := l.getTask(ctx, r.ContainerID)
+	if err != nil {
+		return nil, err
+	}
+	p := runtime.Process(t)
+	if r.ExecID != "" {
+		if p, err = t.Process(ctx, r.ExecID); err != nil {
+			return nil, errdefs.ToGRPC(err)
+		}
+	}
+	if err := p.Kill(ctx, r.Signal, r.All); err != nil {
+		return nil, errdefs.ToGRPC(err)
+	}
+	return empty, nil
+}
+
+func (l *local) ListPids(ctx context.Context, r *api.ListPidsRequest, _ ...grpc.CallOption) (*api.ListPidsResponse, error) {
+	t, err := l.getTask(ctx, r.ContainerID)
+	if err != nil {
+		return nil, err
+	}
+	processList, err := t.Pids(ctx)
+	if err != nil {
+		return nil, errdefs.ToGRPC(err)
+	}
+	var processes []*task.ProcessInfo
+	for _, p := range processList {
+		pInfo := task.ProcessInfo{
+			Pid: p.Pid,
+		}
+		if p.Info != nil {
+			a, err := typeurl.MarshalAny(p.Info)
+			if err != nil {
+				return nil, errors.Wrapf(err, "failed to marshal process %d info", p.Pid)
+			}
+			pInfo.Info = a
+		}
+		processes = append(processes, &pInfo)
+	}
+	return &api.ListPidsResponse{
+		Processes: processes,
+	}, nil
+}
+
+func (l *local) Exec(ctx context.Context, r *api.ExecProcessRequest, _ ...grpc.CallOption) (*ptypes.Empty, error) {
+	if r.ExecID == "" {
+		return nil, status.Errorf(codes.InvalidArgument, "exec id cannot be empty")
+	}
+	t, err := l.getTask(ctx, r.ContainerID)
+	if err != nil {
+		return nil, err
+	}
+	if _, err := t.Exec(ctx, r.ExecID, runtime.ExecOpts{
+		Spec: r.Spec,
+		IO: runtime.IO{
+			Stdin:    r.Stdin,
+			Stdout:   r.Stdout,
+			Stderr:   r.Stderr,
+			Terminal: r.Terminal,
+		},
+	}); err != nil {
+		return nil, errdefs.ToGRPC(err)
+	}
+	return empty, nil
+}
+
+func (l *local) ResizePty(ctx context.Context, r *api.ResizePtyRequest, _ ...grpc.CallOption) (*ptypes.Empty, error) {
+	t, err := l.getTask(ctx, r.ContainerID)
+	if err != nil {
+		return nil, err
+	}
+	p := runtime.Process(t)
+	if r.ExecID != "" {
+		if p, err = t.Process(ctx, r.ExecID); err != nil {
+			return nil, errdefs.ToGRPC(err)
+		}
+	}
+	if err := p.ResizePty(ctx, runtime.ConsoleSize{
+		Width:  r.Width,
+		Height: r.Height,
+	}); err != nil {
+		return nil, errdefs.ToGRPC(err)
+	}
+	return empty, nil
+}
+
+func (l *local) CloseIO(ctx context.Context, r *api.CloseIORequest, _ ...grpc.CallOption) (*ptypes.Empty, error) {
+	t, err := l.getTask(ctx, r.ContainerID)
+	if err != nil {
+		return nil, err
+	}
+	p := runtime.Process(t)
+	if r.ExecID != "" {
+		if p, err = t.Process(ctx, r.ExecID); err != nil {
+			return nil, errdefs.ToGRPC(err)
+		}
+	}
+	if r.Stdin {
+		if err := p.CloseIO(ctx); err != nil {
+			return nil, err
+		}
+	}
+	return empty, nil
+}
+
+func (l *local) Checkpoint(ctx context.Context, r *api.CheckpointTaskRequest, _ ...grpc.CallOption) (*api.CheckpointTaskResponse, error) {
+	container, err := l.getContainer(ctx, r.ContainerID)
+	if err != nil {
+		return nil, err
+	}
+	t, err := l.getTaskFromContainer(ctx, container)
+	if err != nil {
+		return nil, err
+	}
+	image, err := ioutil.TempDir("", "ctd-checkpoint")
+	if err != nil {
+		return nil, errdefs.ToGRPC(err)
+	}
+	defer os.RemoveAll(image)
+	if err := t.Checkpoint(ctx, image, r.Options); err != nil {
+		return nil, errdefs.ToGRPC(err)
+	}
+	// write checkpoint to the content store
+	tar := archive.Diff(ctx, "", image)
+	cp, err := l.writeContent(ctx, images.MediaTypeContainerd1Checkpoint, image, tar)
+	// close tar first after write
+	if err := tar.Close(); err != nil {
+		return nil, err
+	}
+	if err != nil {
+		return nil, err
+	}
+	// write the config to the content store
+	data, err := container.Spec.Marshal()
+	if err != nil {
+		return nil, err
+	}
+	spec := bytes.NewReader(data)
+	specD, err := l.writeContent(ctx, images.MediaTypeContainerd1CheckpointConfig, filepath.Join(image, "spec"), spec)
+	if err != nil {
+		return nil, errdefs.ToGRPC(err)
+	}
+	return &api.CheckpointTaskResponse{
+		Descriptors: []*types.Descriptor{
+			cp,
+			specD,
+		},
+	}, nil
+}
+
+func (l *local) Update(ctx context.Context, r *api.UpdateTaskRequest, _ ...grpc.CallOption) (*ptypes.Empty, error) {
+	t, err := l.getTask(ctx, r.ContainerID)
+	if err != nil {
+		return nil, err
+	}
+	if err := t.Update(ctx, r.Resources); err != nil {
+		return nil, errdefs.ToGRPC(err)
+	}
+	return empty, nil
+}
+
+func (l *local) Metrics(ctx context.Context, r *api.MetricsRequest, _ ...grpc.CallOption) (*api.MetricsResponse, error) {
+	filter, err := filters.ParseAll(r.Filters...)
+	if err != nil {
+		return nil, err
+	}
+	var resp api.MetricsResponse
+	for _, r := range l.runtimes {
+		tasks, err := r.Tasks(ctx)
+		if err != nil {
+			return nil, err
+		}
+		getTasksMetrics(ctx, filter, tasks, &resp)
+	}
+	return &resp, nil
+}
+
+func (l *local) Wait(ctx context.Context, r *api.WaitRequest, _ ...grpc.CallOption) (*api.WaitResponse, error) {
+	t, err := l.getTask(ctx, r.ContainerID)
+	if err != nil {
+		return nil, err
+	}
+	p := runtime.Process(t)
+	if r.ExecID != "" {
+		if p, err = t.Process(ctx, r.ExecID); err != nil {
+			return nil, errdefs.ToGRPC(err)
+		}
+	}
+	exit, err := p.Wait(ctx)
+	if err != nil {
+		return nil, errdefs.ToGRPC(err)
+	}
+	return &api.WaitResponse{
+		ExitStatus: exit.Status,
+		ExitedAt:   exit.Timestamp,
+	}, nil
+}
+
+func getTasksMetrics(ctx context.Context, filter filters.Filter, tasks []runtime.Task, r *api.MetricsResponse) {
+	for _, tk := range tasks {
+		if !filter.Match(filters.AdapterFunc(func(fieldpath []string) (string, bool) {
+			t := tk
+			switch fieldpath[0] {
+			case "id":
+				return t.ID(), true
+			case "namespace":
+				return t.Info().Namespace, true
+			case "runtime":
+				return t.Info().Runtime, true
+			}
+			return "", false
+		})) {
+			continue
+		}
+
+		collected := time.Now()
+		metrics, err := tk.Metrics(ctx)
+		if err != nil {
+			if !errdefs.IsNotFound(err) {
+				log.G(ctx).WithError(err).Errorf("collecting metrics for %s", tk.ID())
+			}
+			continue
+		}
+		data, err := typeurl.MarshalAny(metrics)
+		if err != nil {
+			log.G(ctx).WithError(err).Errorf("marshal metrics for %s", tk.ID())
+			continue
+		}
+		r.Metrics = append(r.Metrics, &types.Metric{
+			ID:        tk.ID(),
+			Timestamp: collected,
+			Data:      data,
+		})
+	}
+}
+
+func (l *local) writeContent(ctx context.Context, mediaType, ref string, r io.Reader) (*types.Descriptor, error) {
+	writer, err := l.store.Writer(ctx, ref, 0, "")
+	if err != nil {
+		return nil, err
+	}
+	defer writer.Close()
+	size, err := io.Copy(writer, r)
+	if err != nil {
+		return nil, err
+	}
+	if err := writer.Commit(ctx, 0, ""); err != nil {
+		return nil, err
+	}
+	return &types.Descriptor{
+		MediaType: mediaType,
+		Digest:    writer.Digest(),
+		Size_:     size,
+	}, nil
+}
+
+func (l *local) getContainer(ctx context.Context, id string) (*containers.Container, error) {
+	var container containers.Container
+	if err := l.db.View(func(tx *bolt.Tx) error {
+		store := metadata.NewContainerStore(tx)
+		var err error
+		container, err = store.Get(ctx, id)
+		return err
+	}); err != nil {
+		return nil, errdefs.ToGRPC(err)
+	}
+	return &container, nil
+}
+
+func (l *local) getTask(ctx context.Context, id string) (runtime.Task, error) {
+	container, err := l.getContainer(ctx, id)
+	if err != nil {
+		return nil, err
+	}
+	return l.getTaskFromContainer(ctx, container)
+}
+
+func (l *local) getTaskFromContainer(ctx context.Context, container *containers.Container) (runtime.Task, error) {
+	runtime, err := l.getRuntime(container.Runtime.Name)
+	if err != nil {
+		return nil, errdefs.ToGRPCf(err, "runtime for task %s", container.Runtime.Name)
+	}
+	t, err := runtime.Get(ctx, container.ID)
+	if err != nil {
+		return nil, status.Errorf(codes.NotFound, "task %v not found", container.ID)
+	}
+	return t, nil
+}
+
+func (l *local) getRuntime(name string) (runtime.Runtime, error) {
+	runtime, ok := l.runtimes[name]
+	if !ok {
+		return nil, status.Errorf(codes.NotFound, "unknown runtime %q", name)
+	}
+	return runtime, nil
+}

services/tasks/service.go

@@ -17,42 +17,17 @@
 package tasks
 
 import (
-	"bytes"
-	"fmt"
-	"io"
-	"io/ioutil"
-	"os"
-	"path/filepath"
-	"time"
-
-	"github.com/boltdb/bolt"
 	api "github.com/containerd/containerd/api/services/tasks/v1"
-	"github.com/containerd/containerd/api/types"
-	"github.com/containerd/containerd/api/types/task"
-	"github.com/containerd/containerd/archive"
-	"github.com/containerd/containerd/containers"
-	"github.com/containerd/containerd/content"
-	"github.com/containerd/containerd/errdefs"
-	"github.com/containerd/containerd/events"
-	"github.com/containerd/containerd/filters"
-	"github.com/containerd/containerd/images"
-	"github.com/containerd/containerd/log"
-	"github.com/containerd/containerd/metadata"
-	"github.com/containerd/containerd/mount"
 	"github.com/containerd/containerd/plugin"
-	"github.com/containerd/containerd/runtime"
-	"github.com/containerd/typeurl"
+	"github.com/containerd/containerd/services"
 	ptypes "github.com/gogo/protobuf/types"
 	"github.com/pkg/errors"
 	"golang.org/x/net/context"
 	"google.golang.org/grpc"
-	"google.golang.org/grpc/codes"
-	"google.golang.org/grpc/status"
 )
 
 var (
-	_     = (api.TasksServer)(&service{})
-	empty = &ptypes.Empty{}
+	_ = (api.TasksServer)(&service{})
 )
 
 func init() {
@@ -60,51 +35,28 @@ func init() {
 		Type: plugin.GRPCPlugin,
 		ID:   "tasks",
 		Requires: []plugin.Type{
-			plugin.RuntimePlugin,
-			plugin.MetadataPlugin,
+			plugin.ServicePlugin,
+		},
+		InitFn: func(ic *plugin.InitContext) (interface{}, error) {
+			plugins, err := ic.GetByType(plugin.ServicePlugin)
+			if err != nil {
+				return nil, err
+			}
+			p, ok := plugins[services.TasksService]
+			if !ok {
+				return nil, errors.New("tasks service not found")
+			}
+			i, err := p.Instance()
+			if err != nil {
+				return nil, err
+			}
+			return &service{local: i.(api.TasksClient)}, nil
 		},
-		InitFn: initFunc,
 	})
 }
 
-func initFunc(ic *plugin.InitContext) (interface{}, error) {
-	rt, err := ic.GetByType(plugin.RuntimePlugin)
-	if err != nil {
-		return nil, err
-	}
-
-	m, err := ic.Get(plugin.MetadataPlugin)
-	if err != nil {
-		return nil, err
-	}
-	cs := m.(*metadata.DB).ContentStore()
-	runtimes := make(map[string]runtime.Runtime)
-	for _, rr := range rt {
-		ri, err := rr.Instance()
-		if err != nil {
-			log.G(ic.Context).WithError(err).Warn("could not load runtime instance due to initialization error")
-			continue
-		}
-		r := ri.(runtime.Runtime)
-		runtimes[r.ID()] = r
-	}
-
-	if len(runtimes) == 0 {
-		return nil, errors.New("no runtimes available to create task service")
-	}
-	return &service{
-		runtimes:  runtimes,
-		db:        m.(*metadata.DB),
-		store:     cs,
-		publisher: ic.Events,
-	}, nil
-}
-
 type service struct {
-	runtimes  map[string]runtime.Runtime
-	db        *metadata.DB
-	store     content.Store
-	publisher events.Publisher
+	local api.TasksClient
 }
 
 func (s *service) Register(server *grpc.Server) error {
@@ -113,526 +65,69 @@ func (s *service) Register(server *grpc.Server) error {
 }
 
 func (s *service) Create(ctx context.Context, r *api.CreateTaskRequest) (*api.CreateTaskResponse, error) {
-	var (
-		checkpointPath string
-		err            error
-	)
-	if r.Checkpoint != nil {
-		checkpointPath, err = ioutil.TempDir("", "ctrd-checkpoint")
-		if err != nil {
-			return nil, err
-		}
-		if r.Checkpoint.MediaType != images.MediaTypeContainerd1Checkpoint {
-			return nil, fmt.Errorf("unsupported checkpoint type %q", r.Checkpoint.MediaType)
-		}
-		reader, err := s.store.ReaderAt(ctx, r.Checkpoint.Digest)
-		if err != nil {
-			return nil, err
-		}
-		_, err = archive.Apply(ctx, checkpointPath, content.NewReader(reader))
-		reader.Close()
-		if err != nil {
-			return nil, err
-		}
-	}
-
-	container, err := s.getContainer(ctx, r.ContainerID)
-	if err != nil {
-		return nil, errdefs.ToGRPC(err)
-	}
-	opts := runtime.CreateOpts{
-		Spec: container.Spec,
-		IO: runtime.IO{
-			Stdin:    r.Stdin,
-			Stdout:   r.Stdout,
-			Stderr:   r.Stderr,
-			Terminal: r.Terminal,
-		},
-		Checkpoint: checkpointPath,
-		Options:    r.Options,
-	}
-	for _, m := range r.Rootfs {
-		opts.Rootfs = append(opts.Rootfs, mount.Mount{
-			Type:    m.Type,
-			Source:  m.Source,
-			Options: m.Options,
-		})
-	}
-	runtime, err := s.getRuntime(container.Runtime.Name)
-	if err != nil {
-		return nil, err
-	}
-	c, err := runtime.Create(ctx, r.ContainerID, opts)
-	if err != nil {
-		return nil, errdefs.ToGRPC(err)
-	}
-	state, err := c.State(ctx)
-	if err != nil {
-		log.G(ctx).Error(err)
-	}
-
-	return &api.CreateTaskResponse{
-		ContainerID: r.ContainerID,
-		Pid:         state.Pid,
-	}, nil
+	return s.local.Create(ctx, r)
 }
 
 func (s *service) Start(ctx context.Context, r *api.StartRequest) (*api.StartResponse, error) {
-	t, err := s.getTask(ctx, r.ContainerID)
-	if err != nil {
-		return nil, err
-	}
-	p := runtime.Process(t)
-	if r.ExecID != "" {
-		if p, err = t.Process(ctx, r.ExecID); err != nil {
-			return nil, errdefs.ToGRPC(err)
-		}
-	}
-	if err := p.Start(ctx); err != nil {
-		return nil, errdefs.ToGRPC(err)
-	}
-	state, err := p.State(ctx)
-	if err != nil {
-		return nil, errdefs.ToGRPC(err)
-	}
-	return &api.StartResponse{
-		Pid: state.Pid,
-	}, nil
+	return s.local.Start(ctx, r)
 }
 
 func (s *service) Delete(ctx context.Context, r *api.DeleteTaskRequest) (*api.DeleteResponse, error) {
-	t, err := s.getTask(ctx, r.ContainerID)
-	if err != nil {
-		return nil, err
-	}
-	runtime, err := s.getRuntime(t.Info().Runtime)
-	if err != nil {
-		return nil, err
-	}
-	exit, err := runtime.Delete(ctx, t)
-	if err != nil {
-		return nil, errdefs.ToGRPC(err)
-	}
-	return &api.DeleteResponse{
-		ExitStatus: exit.Status,
-		ExitedAt:   exit.Timestamp,
-		Pid:        exit.Pid,
-	}, nil
+	return s.local.Delete(ctx, r)
 }
 
 func (s *service) DeleteProcess(ctx context.Context, r *api.DeleteProcessRequest) (*api.DeleteResponse, error) {
-	t, err := s.getTask(ctx, r.ContainerID)
-	if err != nil {
-		return nil, err
-	}
-	exit, err := t.DeleteProcess(ctx, r.ExecID)
-	if err != nil {
-		return nil, errdefs.ToGRPC(err)
-	}
-	return &api.DeleteResponse{
-		ID:         r.ExecID,
-		ExitStatus: exit.Status,
-		ExitedAt:   exit.Timestamp,
-		Pid:        exit.Pid,
-	}, nil
-}
-
-func processFromContainerd(ctx context.Context, p runtime.Process) (*task.Process, error) {
-	state, err := p.State(ctx)
-	if err != nil {
-		return nil, err
-	}
-	var status task.Status
-	switch state.Status {
-	case runtime.CreatedStatus:
-		status = task.StatusCreated
-	case runtime.RunningStatus:
-		status = task.StatusRunning
-	case runtime.StoppedStatus:
-		status = task.StatusStopped
-	case runtime.PausedStatus:
-		status = task.StatusPaused
-	case runtime.PausingStatus:
-		status = task.StatusPausing
-	default:
-		log.G(ctx).WithField("status", state.Status).Warn("unknown status")
-	}
-	return &task.Process{
-		ID:         p.ID(),
-		Pid:        state.Pid,
-		Status:     status,
-		Stdin:      state.Stdin,
-		Stdout:     state.Stdout,
-		Stderr:     state.Stderr,
-		Terminal:   state.Terminal,
-		ExitStatus: state.ExitStatus,
-		ExitedAt:   state.ExitedAt,
-	}, nil
+	return s.local.DeleteProcess(ctx, r)
 }
 
 func (s *service) Get(ctx context.Context, r *api.GetRequest) (*api.GetResponse, error) {
-	task, err := s.getTask(ctx, r.ContainerID)
-	if err != nil {
-		return nil, err
-	}
-	p := runtime.Process(task)
-	if r.ExecID != "" {
-		if p, err = task.Process(ctx, r.ExecID); err != nil {
-			return nil, errdefs.ToGRPC(err)
-		}
-	}
-	t, err := processFromContainerd(ctx, p)
-	if err != nil {
-		return nil, errdefs.ToGRPC(err)
-	}
-	return &api.GetResponse{
-		Process: t,
-	}, nil
+	return s.local.Get(ctx, r)
 }
 
 func (s *service) List(ctx context.Context, r *api.ListTasksRequest) (*api.ListTasksResponse, error) {
-	resp := &api.ListTasksResponse{}
-	for _, r := range s.runtimes {
-		tasks, err := r.Tasks(ctx)
-		if err != nil {
-			return nil, errdefs.ToGRPC(err)
-		}
-		addTasks(ctx, resp, tasks)
-	}
-	return resp, nil
-}
-
-func addTasks(ctx context.Context, r *api.ListTasksResponse, tasks []runtime.Task) {
-	for _, t := range tasks {
-		tt, err := processFromContainerd(ctx, t)
-		if err != nil {
-			if !errdefs.IsNotFound(err) { // handle race with deletion
-				log.G(ctx).WithError(err).WithField("id", t.ID()).Error("converting task to protobuf")
-			}
-			continue
-		}
-		r.Tasks = append(r.Tasks, tt)
-	}
+	return s.local.List(ctx, r)
 }
 
 func (s *service) Pause(ctx context.Context, r *api.PauseTaskRequest) (*ptypes.Empty, error) {
-	t, err := s.getTask(ctx, r.ContainerID)
-	if err != nil {
-		return nil, err
-	}
-	err = t.Pause(ctx)
-	if err != nil {
-		return nil, errdefs.ToGRPC(err)
-	}
-	return empty, nil
+	return s.local.Pause(ctx, r)
 }
 
 func (s *service) Resume(ctx context.Context, r *api.ResumeTaskRequest) (*ptypes.Empty, error) {
-	t, err := s.getTask(ctx, r.ContainerID)
-	if err != nil {
-		return nil, err
-	}
-	err = t.Resume(ctx)
-	if err != nil {
-		return nil, errdefs.ToGRPC(err)
-	}
-	return empty, nil
+	return s.local.Resume(ctx, r)
 }
 
 func (s *service) Kill(ctx context.Context, r *api.KillRequest) (*ptypes.Empty, error) {
-	t, err := s.getTask(ctx, r.ContainerID)
-	if err != nil {
-		return nil, err
-	}
-	p := runtime.Process(t)
-	if r.ExecID != "" {
-		if p, err = t.Process(ctx, r.ExecID); err != nil {
-			return nil, errdefs.ToGRPC(err)
-		}
-	}
-	if err := p.Kill(ctx, r.Signal, r.All); err != nil {
-		return nil, errdefs.ToGRPC(err)
-	}
-	return empty, nil
+	return s.local.Kill(ctx, r)
 }
 
 func (s *service) ListPids(ctx context.Context, r *api.ListPidsRequest) (*api.ListPidsResponse, error) {
-	t, err := s.getTask(ctx, r.ContainerID)
-	if err != nil {
-		return nil, err
-	}
-	processList, err := t.Pids(ctx)
-	if err != nil {
-		return nil, errdefs.ToGRPC(err)
-	}
-	var processes []*task.ProcessInfo
-	for _, p := range processList {
-		pInfo := task.ProcessInfo{
-			Pid: p.Pid,
-		}
-		if p.Info != nil {
-			a, err := typeurl.MarshalAny(p.Info)
-			if err != nil {
-				return nil, errors.Wrapf(err, "failed to marshal process %d info", p.Pid)
-			}
-			pInfo.Info = a
-		}
-		processes = append(processes, &pInfo)
-	}
-	return &api.ListPidsResponse{
-		Processes: processes,
-	}, nil
+	return s.local.ListPids(ctx, r)
 }
 
 func (s *service) Exec(ctx context.Context, r *api.ExecProcessRequest) (*ptypes.Empty, error) {
-	if r.ExecID == "" {
-		return nil, status.Errorf(codes.InvalidArgument, "exec id cannot be empty")
-	}
-	t, err := s.getTask(ctx, r.ContainerID)
-	if err != nil {
-		return nil, err
-	}
-	if _, err := t.Exec(ctx, r.ExecID, runtime.ExecOpts{
-		Spec: r.Spec,
-		IO: runtime.IO{
-			Stdin:    r.Stdin,
-			Stdout:   r.Stdout,
-			Stderr:   r.Stderr,
-			Terminal: r.Terminal,
-		},
-	}); err != nil {
-		return nil, errdefs.ToGRPC(err)
-	}
-	return empty, nil
+	return s.local.Exec(ctx, r)
 }
 
 func (s *service) ResizePty(ctx context.Context, r *api.ResizePtyRequest) (*ptypes.Empty, error) {
-	t, err := s.getTask(ctx, r.ContainerID)
-	if err != nil {
-		return nil, err
-	}
-	p := runtime.Process(t)
-	if r.ExecID != "" {
-		if p, err = t.Process(ctx, r.ExecID); err != nil {
-			return nil, errdefs.ToGRPC(err)
-		}
-	}
-	if err := p.ResizePty(ctx, runtime.ConsoleSize{
-		Width:  r.Width,
-		Height: r.Height,
-	}); err != nil {
-		return nil, errdefs.ToGRPC(err)
-	}
-	return empty, nil
+	return s.local.ResizePty(ctx, r)
 }
 
 func (s *service) CloseIO(ctx context.Context, r *api.CloseIORequest) (*ptypes.Empty, error) {
-	t, err := s.getTask(ctx, r.ContainerID)
-	if err != nil {
-		return nil, err
-	}
-	p := runtime.Process(t)
-	if r.ExecID != "" {
-		if p, err = t.Process(ctx, r.ExecID); err != nil {
-			return nil, errdefs.ToGRPC(err)
-		}
-	}
-	if r.Stdin {
-		if err := p.CloseIO(ctx); err != nil {
-			return nil, err
-		}
-	}
-	return empty, nil
+	return s.local.CloseIO(ctx, r)
 }
 
 func (s *service) Checkpoint(ctx context.Context, r *api.CheckpointTaskRequest) (*api.CheckpointTaskResponse, error) {
-	container, err := s.getContainer(ctx, r.ContainerID)
-	if err != nil {
-		return nil, err
-	}
-	t, err := s.getTaskFromContainer(ctx, container)
-	if err != nil {
-		return nil, err
-	}
-	image, err := ioutil.TempDir("", "ctd-checkpoint")
-	if err != nil {
-		return nil, errdefs.ToGRPC(err)
-	}
-	defer os.RemoveAll(image)
-	if err := t.Checkpoint(ctx, image, r.Options); err != nil {
-		return nil, errdefs.ToGRPC(err)
-	}
-	// write checkpoint to the content store
-	tar := archive.Diff(ctx, "", image)
-	cp, err := s.writeContent(ctx, images.MediaTypeContainerd1Checkpoint, image, tar)
-	// close tar first after write
-	if err := tar.Close(); err != nil {
-		return nil, err
-	}
-	if err != nil {
-		return nil, err
-	}
-	// write the config to the content store
-	data, err := container.Spec.Marshal()
-	if err != nil {
-		return nil, err
-	}
-	spec := bytes.NewReader(data)
-	specD, err := s.writeContent(ctx, images.MediaTypeContainerd1CheckpointConfig, filepath.Join(image, "spec"), spec)
-	if err != nil {
-		return nil, errdefs.ToGRPC(err)
-	}
-	return &api.CheckpointTaskResponse{
-		Descriptors: []*types.Descriptor{
-			cp,
-			specD,
-		},
-	}, nil
+	return s.local.Checkpoint(ctx, r)
 }
 
 func (s *service) Update(ctx context.Context, r *api.UpdateTaskRequest) (*ptypes.Empty, error) {
-	t, err := s.getTask(ctx, r.ContainerID)
-	if err != nil {
-		return nil, err
-	}
-	if err := t.Update(ctx, r.Resources); err != nil {
-		return nil, errdefs.ToGRPC(err)
-	}
-	return empty, nil
+	return s.local.Update(ctx, r)
 }
 
 func (s *service) Metrics(ctx context.Context, r *api.MetricsRequest) (*api.MetricsResponse, error) {
-	filter, err := filters.ParseAll(r.Filters...)
-	if err != nil {
-		return nil, err
-	}
-	var resp api.MetricsResponse
-	for _, r := range s.runtimes {
-		tasks, err := r.Tasks(ctx)
-		if err != nil {
-			return nil, err
-		}
-		getTasksMetrics(ctx, filter, tasks, &resp)
-	}
-	return &resp, nil
+	return s.local.Metrics(ctx, r)
 }
 
 func (s *service) Wait(ctx context.Context, r *api.WaitRequest) (*api.WaitResponse, error) {
-	t, err := s.getTask(ctx, r.ContainerID)
-	if err != nil {
-		return nil, err
-	}
-	p := runtime.Process(t)
-	if r.ExecID != "" {
-		if p, err = t.Process(ctx, r.ExecID); err != nil {
-			return nil, errdefs.ToGRPC(err)
-		}
-	}
-	exit, err := p.Wait(ctx)
-	if err != nil {
-		return nil, errdefs.ToGRPC(err)
-	}
-	return &api.WaitResponse{
-		ExitStatus: exit.Status,
-		ExitedAt:   exit.Timestamp,
-	}, nil
-}
-
-func getTasksMetrics(ctx context.Context, filter filters.Filter, tasks []runtime.Task, r *api.MetricsResponse) {
-	for _, tk := range tasks {
-		if !filter.Match(filters.AdapterFunc(func(fieldpath []string) (string, bool) {
-			t := tk
-			switch fieldpath[0] {
-			case "id":
-				return t.ID(), true
-			case "namespace":
-				return t.Info().Namespace, true
-			case "runtime":
-				return t.Info().Runtime, true
-			}
-			return "", false
-		})) {
-			continue
-		}
-
-		collected := time.Now()
-		metrics, err := tk.Metrics(ctx)
-		if err != nil {
-			if !errdefs.IsNotFound(err) {
-				log.G(ctx).WithError(err).Errorf("collecting metrics for %s", tk.ID())
-			}
-			continue
-		}
-		data, err := typeurl.MarshalAny(metrics)
-		if err != nil {
-			log.G(ctx).WithError(err).Errorf("marshal metrics for %s", tk.ID())
-			continue
-		}
-		r.Metrics = append(r.Metrics, &types.Metric{
-			ID:        tk.ID(),
-			Timestamp: collected,
-			Data:      data,
-		})
-	}
-}
-
-func (s *service) writeContent(ctx context.Context, mediaType, ref string, r io.Reader) (*types.Descriptor, error) {
-	writer, err := s.store.Writer(ctx, ref, 0, "")
-	if err != nil {
-		return nil, err
-	}
-	defer writer.Close()
-	size, err := io.Copy(writer, r)
-	if err != nil {
-		return nil, err
-	}
-	if err := writer.Commit(ctx, 0, ""); err != nil {
-		return nil, err
-	}
-	return &types.Descriptor{
-		MediaType: mediaType,
-		Digest:    writer.Digest(),
-		Size_:     size,
-	}, nil
-}
-
-func (s *service) getContainer(ctx context.Context, id string) (*containers.Container, error) {
-	var container containers.Container
-	if err := s.db.View(func(tx *bolt.Tx) error {
-		store := metadata.NewContainerStore(tx)
-		var err error
-		container, err = store.Get(ctx, id)
-		return err
-	}); err != nil {
-		return nil, errdefs.ToGRPC(err)
-	}
-	return &container, nil
-}
-
-func (s *service) getTask(ctx context.Context, id string) (runtime.Task, error) {
-	container, err := s.getContainer(ctx, id)
-	if err != nil {
-		return nil, err
-	}
-	return s.getTaskFromContainer(ctx, container)
-}
-
-func (s *service) getTaskFromContainer(ctx context.Context, container *containers.Container) (runtime.Task, error) {
-	runtime, err := s.getRuntime(container.Runtime.Name)
-	if err != nil {
-		return nil, errdefs.ToGRPCf(err, "runtime for task %s", container.Runtime.Name)
-	}
-	t, err := runtime.Get(ctx, container.ID)
-	if err != nil {
-		return nil, status.Errorf(codes.NotFound, "task %v not found", container.ID)
-	}
-	return t, nil
-}
-
-func (s *service) getRuntime(name string) (runtime.Runtime, error) {
-	runtime, ok := s.runtimes[name]
-	if !ok {
-		return nil, status.Errorf(codes.NotFound, "unknown runtime %q", name)
-	}
-	return runtime, nil
+	return s.local.Wait(ctx, r)
 }