images, services/images: implement image service

Server and Client images of the image store are now provided. We have
created an image metadata interface and converted the bolt functions to
implement that interface over an transaction. A remote client
implementation is provided that implements the same interface.

Signed-off-by: Stephen J Day <stephen.day@docker.com>

images/image.go

@@ -14,8 +14,8 @@ import (
 
 // Image provides the model for how containerd views container images.
 type Image struct {
-	Name       string
+	Name   string
-	Descriptor ocispec.Descriptor
+	Target ocispec.Descriptor
 }
 
 // TODO(stevvooe): Many of these functions make strong platform assumptions,
@@ -29,9 +29,9 @@ type Image struct {
 func (image *Image) Config(ctx context.Context, provider content.Provider) (ocispec.Descriptor, error) {
 	var configDesc ocispec.Descriptor
 	return configDesc, Walk(ctx, HandlerFunc(func(ctx context.Context, desc ocispec.Descriptor) ([]ocispec.Descriptor, error) {
-		switch image.Descriptor.MediaType {
+		switch image.Target.MediaType {
 		case MediaTypeDockerSchema2Manifest, ocispec.MediaTypeImageManifest:
-			rc, err := provider.Reader(ctx, image.Descriptor.Digest)
+			rc, err := provider.Reader(ctx, image.Target.Digest)
 			if err != nil {
 				return nil, err
 			}
@@ -54,7 +54,7 @@ func (image *Image) Config(ctx context.Context, provider content.Provider) (ocis
 			return nil, errors.New("could not resolve config")
 		}
 
-	}), image.Descriptor)
+	}), image.Target)
 }
 
 // RootFS returns the unpacked diffids that make up and images rootfs.
@@ -91,10 +91,10 @@ func (image *Image) RootFS(ctx context.Context, provider content.Provider) ([]di
 func (image *Image) Size(ctx context.Context, provider content.Provider) (int64, error) {
 	var size int64
 	return size, Walk(ctx, HandlerFunc(func(ctx context.Context, desc ocispec.Descriptor) ([]ocispec.Descriptor, error) {
-		switch image.Descriptor.MediaType {
+		switch image.Target.MediaType {
 		case MediaTypeDockerSchema2Manifest, ocispec.MediaTypeImageManifest:
 			size += desc.Size
-			rc, err := provider.Reader(ctx, image.Descriptor.Digest)
+			rc, err := provider.Reader(ctx, image.Target.Digest)
 			if err != nil {
 				return nil, err
 			}
@@ -121,5 +121,5 @@ func (image *Image) Size(ctx context.Context, provider content.Provider) (int64,
 			return nil, errors.New("unsupported type")
 		}
 
-	}), image.Descriptor)
+	}), image.Target)
 }

images/storage.go

@@ -1,6 +1,7 @@
 package images
 
 import (
+	"context"
 	"encoding/binary"
 	"fmt"
 
@@ -8,12 +9,30 @@ import (
 	"github.com/containerd/containerd/log"
 	digest "github.com/opencontainers/go-digest"
 	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
+	"github.com/pkg/errors"
 )
 
 var (
-	errImageUnknown = fmt.Errorf("image: unknown")
+	ErrExists   = errors.New("images: exists")
+	ErrNotFound = errors.New("images: not found")
 )
 
+type Store interface {
+	Put(ctx context.Context, name string, desc ocispec.Descriptor) error
+	Get(ctx context.Context, name string) (Image, error)
+	List(ctx context.Context) ([]Image, error)
+	Delete(ctx context.Context, name string) error
+}
+
+// IsNotFound returns true if the error is due to a missing image.
+func IsNotFound(err error) bool {
+	return errors.Cause(err) == ErrNotFound
+}
+
+func IsExists(err error) bool {
+	return errors.Cause(err) == ErrExists
+}
+
 var (
 	bucketKeyStorageVersion = []byte("v1")
 	bucketKeyImages         = []byte("images")
@@ -26,6 +45,8 @@ var (
 // "metadata" store. For now, it is bound tightly to the local machine and bolt
 // but we can take this and use it to define a service interface.
 
+// InitDB will initialize the database for use. The database must be opened for
+// write and the caller must not be holding an open transaction.
 func InitDB(db *bolt.DB) error {
 	log.L.Debug("init db")
 	return db.Update(func(tx *bolt.Tx) error {
@@ -34,8 +55,28 @@ func InitDB(db *bolt.DB) error {
 	})
 }
 
-func Register(tx *bolt.Tx, name string, desc ocispec.Descriptor) error {
+func NewImageStore(tx *bolt.Tx) Store {
-	return withImagesBucket(tx, func(bkt *bolt.Bucket) error {
+	return &storage{tx: tx}
+}
+
+type storage struct {
+	tx *bolt.Tx
+}
+
+func (s *storage) Get(ctx context.Context, name string) (Image, error) {
+	var image Image
+	if err := withImageBucket(s.tx, name, func(bkt *bolt.Bucket) error {
+		image.Name = name
+		return readImage(&image, bkt)
+	}); err != nil {
+		return Image{}, err
+	}
+
+	return image, nil
+}
+
+func (s *storage) Put(ctx context.Context, name string, desc ocispec.Descriptor) error {
+	return withImagesBucket(s.tx, func(bkt *bolt.Bucket) error {
 		ibkt, err := bkt.CreateBucketIfNotExists([]byte(name))
 		if err != nil {
 			return err
@@ -65,22 +106,10 @@ func Register(tx *bolt.Tx, name string, desc ocispec.Descriptor) error {
 	})
 }
 
-func Get(tx *bolt.Tx, name string) (Image, error) {
+func (s *storage) List(ctx context.Context) ([]Image, error) {
-	var image Image
-	if err := withImageBucket(tx, name, func(bkt *bolt.Bucket) error {
-		image.Name = name
-		return readImage(&image, bkt)
-	}); err != nil {
-		return Image{}, err
-	}
-
-	return image, nil
-}
-
-func List(tx *bolt.Tx) ([]Image, error) {
 	var images []Image
 
-	if err := withImagesBucket(tx, func(bkt *bolt.Bucket) error {
+	if err := withImagesBucket(s.tx, func(bkt *bolt.Bucket) error {
 		return bkt.ForEach(func(k, v []byte) error {
 			var (
 				image = Image{
@@ -103,8 +132,8 @@ func List(tx *bolt.Tx) ([]Image, error) {
 	return images, nil
 }
 
-func Delete(tx *bolt.Tx, name string) error {
+func (s *storage) Delete(ctx context.Context, name string) error {
-	return withImagesBucket(tx, func(bkt *bolt.Bucket) error {
+	return withImagesBucket(s.tx, func(bkt *bolt.Bucket) error {
 		return bkt.DeleteBucket([]byte(name))
 	})
 }
@@ -119,11 +148,11 @@ func readImage(image *Image, bkt *bolt.Bucket) error {
 		// keys, rather than full arrays.
 		switch string(k) {
 		case string(bucketKeyDigest):
-			image.Descriptor.Digest = digest.Digest(v)
+			image.Target.Digest = digest.Digest(v)
 		case string(bucketKeyMediaType):
-			image.Descriptor.MediaType = string(v)
+			image.Target.MediaType = string(v)
 		case string(bucketKeySize):
-			image.Descriptor.Size, _ = binary.Varint(v)
+			image.Target.Size, _ = binary.Varint(v)
 		}
 
 		return nil
@@ -149,7 +178,7 @@ func createBucketIfNotExists(tx *bolt.Tx, keys ...[]byte) (*bolt.Bucket, error)
 func withImagesBucket(tx *bolt.Tx, fn func(bkt *bolt.Bucket) error) error {
 	bkt := getImagesBucket(tx)
 	if bkt == nil {
-		return errImageUnknown
+		return ErrNotFound
 	}
 
 	return fn(bkt)
@@ -158,7 +187,7 @@ func withImagesBucket(tx *bolt.Tx, fn func(bkt *bolt.Bucket) error) error {
 func withImageBucket(tx *bolt.Tx, name string, fn func(bkt *bolt.Bucket) error) error {
 	bkt := getImageBucket(tx, name)
 	if bkt == nil {
-		return errImageUnknown
+		return ErrNotFound
 	}
 
 	return fn(bkt)

services/images/client.go

@@ -0,0 +1,60 @@
+package images
+
+import (
+	"context"
+
+	imagesapi "github.com/containerd/containerd/api/services/images"
+	"github.com/containerd/containerd/images"
+	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
+)
+
+type remoteStore struct {
+	client imagesapi.ImagesClient
+}
+
+func NewStoreFromClient(client imagesapi.ImagesClient) images.Store {
+	return &remoteStore{
+		client: client,
+	}
+}
+
+func (s *remoteStore) Put(ctx context.Context, name string, desc ocispec.Descriptor) error {
+	// TODO(stevvooe): Consider that the remote may want to augment and return
+	// a modified image.
+	_, err := s.client.Put(ctx, &imagesapi.PutRequest{
+		Image: imagesapi.Image{
+			Name:   name,
+			Target: descToProto(&desc),
+		},
+	})
+
+	return rewriteGRPCError(err)
+}
+
+func (s *remoteStore) Get(ctx context.Context, name string) (images.Image, error) {
+	resp, err := s.client.Get(ctx, &imagesapi.GetRequest{
+		Name: name,
+	})
+	if err != nil {
+		return images.Image{}, rewriteGRPCError(err)
+	}
+
+	return imageFromProto(resp.Image), nil
+}
+
+func (s *remoteStore) List(ctx context.Context) ([]images.Image, error) {
+	resp, err := s.client.List(ctx, &imagesapi.ListRequest{})
+	if err != nil {
+		return nil, rewriteGRPCError(err)
+	}
+
+	return imagesFromProto(resp.Images), nil
+}
+
+func (s *remoteStore) Delete(ctx context.Context, name string) error {
+	_, err := s.client.Delete(ctx, &imagesapi.DeleteRequest{
+		Name: name,
+	})
+
+	return rewriteGRPCError(err)
+}

services/images/helpers.go

@@ -0,0 +1,87 @@
+package images
+
+import (
+	imagesapi "github.com/containerd/containerd/api/services/images"
+	"github.com/containerd/containerd/api/types/descriptor"
+	"github.com/containerd/containerd/images"
+	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
+	"github.com/pkg/errors"
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/codes"
+)
+
+func imagesToProto(images []images.Image) []imagesapi.Image {
+	var imagespb []imagesapi.Image
+
+	for _, image := range images {
+		imagespb = append(imagespb, imageToProto(&image))
+	}
+
+	return imagespb
+}
+
+func imagesFromProto(imagespb []imagesapi.Image) []images.Image {
+	var images []images.Image
+
+	for _, image := range imagespb {
+		images = append(images, imageFromProto(&image))
+	}
+
+	return images
+}
+
+func imageToProto(image *images.Image) imagesapi.Image {
+	return imagesapi.Image{
+		Name:   image.Name,
+		Target: descToProto(&image.Target),
+	}
+}
+
+func imageFromProto(imagepb *imagesapi.Image) images.Image {
+	return images.Image{
+		Name:   imagepb.Name,
+		Target: descFromProto(&imagepb.Target),
+	}
+}
+
+func descFromProto(desc *descriptor.Descriptor) ocispec.Descriptor {
+	return ocispec.Descriptor{
+		MediaType: desc.MediaType,
+		Size:      desc.Size_,
+		Digest:    desc.Digest,
+	}
+}
+
+func descToProto(desc *ocispec.Descriptor) descriptor.Descriptor {
+	return descriptor.Descriptor{
+		MediaType: desc.MediaType,
+		Size_:     desc.Size,
+		Digest:    desc.Digest,
+	}
+}
+
+func rewriteGRPCError(err error) error {
+	if err == nil {
+		return err
+	}
+
+	switch grpc.Code(errors.Cause(err)) {
+	case codes.AlreadyExists:
+		return images.ErrExists
+	case codes.NotFound:
+		return images.ErrNotFound
+	}
+
+	return err
+}
+
+func mapGRPCError(err error, id string) error {
+	switch {
+	case images.IsNotFound(err):
+		return grpc.Errorf(codes.NotFound, "image %v not found", id)
+	case images.IsExists(err):
+		return grpc.Errorf(codes.AlreadyExists, "image %v already exists", id)
+	}
+
+	return err
+}

services/images/service.go

@@ -1,32 +1,91 @@
 package images
 
 import (
-	imagesapi "github.com/docker/containerd/api/services/images"
+	"github.com/boltdb/bolt"
-	"github.com/docker/containerd/images"
+	imagesapi "github.com/containerd/containerd/api/services/images"
+	"github.com/containerd/containerd/images"
+	"github.com/containerd/containerd/plugin"
 	"github.com/golang/protobuf/ptypes/empty"
 	"golang.org/x/net/context"
+	"google.golang.org/grpc"
 )
 
+func init() {
+	plugin.Register("images-grpc", &plugin.Registration{
+		Type: plugin.GRPCPlugin,
+		Init: func(ic *plugin.InitContext) (interface{}, error) {
+			return NewService(ic.Meta), nil
+		},
+	})
+}
+
 type Service struct {
-	store images.Store
+	db *bolt.DB
 }
 
-func NewService(store images.Store) imagesapi.ImagesServer {
+func NewService(db *bolt.DB) imagesapi.ImagesServer {
-	return &Service{store: store}
+	return &Service{db: db}
 }
 
-func (s *Service) Get(context.Context, *imagesapi.GetRequest) (*imagesapi.GetResponse, error) {
+func (s *Service) Register(server *grpc.Server) error {
-	panic("not implemented")
+	imagesapi.RegisterImagesServer(server, s)
+	return nil
 }
 
-func (s *Service) Register(context.Context, *imagesapi.RegisterRequest) (*imagesapi.RegisterRequest, error) {
+func (s *Service) Get(ctx context.Context, req *imagesapi.GetRequest) (*imagesapi.GetResponse, error) {
-	panic("not implemented")
+	var resp imagesapi.GetResponse
+
+	return &resp, s.withStoreTx(ctx, req.Name, false, func(ctx context.Context, store images.Store) error {
+		image, err := store.Get(ctx, req.Name)
+		if err != nil {
+			return mapGRPCError(err, req.Name)
+		}
+		imagepb := imageToProto(&image)
+		resp.Image = &imagepb
+		return nil
+	})
 }
 
-func (s *Service) List(context.Context, *imagesapi.ListRequest) (*imagesapi.ListResponse, error) {
+func (s *Service) Put(ctx context.Context, req *imagesapi.PutRequest) (*empty.Empty, error) {
-	panic("not implemented")
+	return &empty.Empty{}, s.withStoreTx(ctx, req.Image.Name, true, func(ctx context.Context, store images.Store) error {
+		return mapGRPCError(store.Put(ctx, req.Image.Name, descFromProto(&req.Image.Target)), req.Image.Name)
+	})
 }
 
-func (s *Service) Delete(context.Context, *imagesapi.DeleteRequest) (*empty.Empty, error) {
+func (s *Service) List(ctx context.Context, _ *imagesapi.ListRequest) (*imagesapi.ListResponse, error) {
-	panic("not implemented")
+	var resp imagesapi.ListResponse
+
+	return &resp, s.withStoreTx(ctx, "", false, func(ctx context.Context, store images.Store) error {
+		images, err := store.List(ctx)
+		if err != nil {
+			return mapGRPCError(err, "")
+		}
+
+		resp.Images = imagesToProto(images)
+		return nil
+	})
+}
+
+func (s *Service) Delete(ctx context.Context, req *imagesapi.DeleteRequest) (*empty.Empty, error) {
+	return &empty.Empty{}, s.withStoreTx(ctx, req.Name, true, func(ctx context.Context, store images.Store) error {
+		return mapGRPCError(store.Delete(ctx, req.Name), req.Name)
+	})
+}
+
+func (s *Service) withStoreTx(ctx context.Context, id string, writable bool, fn func(ctx context.Context, store images.Store) error) error {
+	tx, err := s.db.Begin(writable)
+	if err != nil {
+		return mapGRPCError(err, id)
+	}
+	defer tx.Rollback()
+
+	if err := fn(ctx, images.NewImageStore(tx)); err != nil {
+		return err
+	}
+
+	if writable {
+		return tx.Commit()
+	}
+
+	return nil
 }