Implements garbage collection subcommand

- Includes a change in the command to run the registry. The registry
  server itself is now started up as a subcommand.
- Includes changes to the high level interfaces to support enumeration
  of various registry objects.

Signed-off-by: Andrew T Nguyen <andrew.nguyen@docker.com>

docs/garbagecollect.go

@@ -0,0 +1,150 @@
+package registry
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/docker/distribution"
+	"github.com/docker/distribution/context"
+	"github.com/docker/distribution/digest"
+	"github.com/docker/distribution/manifest/schema1"
+	"github.com/docker/distribution/manifest/schema2"
+	"github.com/docker/distribution/reference"
+	"github.com/docker/distribution/registry/storage"
+	"github.com/docker/distribution/registry/storage/driver"
+	"github.com/docker/distribution/registry/storage/driver/factory"
+
+	"github.com/spf13/cobra"
+)
+
+func markAndSweep(storageDriver driver.StorageDriver) error {
+	ctx := context.Background()
+
+	// Construct a registry
+	registry, err := storage.NewRegistry(ctx, storageDriver)
+	if err != nil {
+		return fmt.Errorf("failed to construct registry: %v", err)
+	}
+
+	repositoryEnumerator, ok := registry.(distribution.RepositoryEnumerator)
+	if !ok {
+		return fmt.Errorf("coercion error: unable to convert Namespace to RepositoryEnumerator")
+	}
+
+	// mark
+	markSet := make(map[digest.Digest]struct{})
+	err = repositoryEnumerator.Enumerate(ctx, func(repoName string) error {
+		var err error
+		named, err := reference.ParseNamed(repoName)
+		if err != nil {
+			return fmt.Errorf("failed to parse repo name %s: %v", repoName, err)
+		}
+		repository, err := registry.Repository(ctx, named)
+		if err != nil {
+			return fmt.Errorf("failed to construct repository: %v", err)
+		}
+
+		manifestService, err := repository.Manifests(ctx)
+		if err != nil {
+			return fmt.Errorf("failed to construct manifest service: %v", err)
+		}
+
+		manifestEnumerator, ok := manifestService.(distribution.ManifestEnumerator)
+		if !ok {
+			return fmt.Errorf("coercion error: unable to convert ManifestService into ManifestEnumerator")
+		}
+
+		err = manifestEnumerator.Enumerate(ctx, func(dgst digest.Digest) error {
+			// Mark the manifest's blob
+			markSet[dgst] = struct{}{}
+
+			manifest, err := manifestService.Get(ctx, dgst)
+			if err != nil {
+				return fmt.Errorf("failed to retrieve manifest for digest %v: %v", dgst, err)
+			}
+
+			descriptors := manifest.References()
+			for _, descriptor := range descriptors {
+				markSet[descriptor.Digest] = struct{}{}
+			}
+
+			switch manifest.(type) {
+			case *schema1.SignedManifest:
+				signaturesGetter, ok := manifestService.(distribution.SignaturesGetter)
+				if !ok {
+					return fmt.Errorf("coercion error: unable to convert ManifestSErvice into SignaturesGetter")
+				}
+				signatures, err := signaturesGetter.GetSignatures(ctx, dgst)
+				if err != nil {
+					return fmt.Errorf("failed to get signatures for signed manifest: %v", err)
+				}
+				for _, signatureDigest := range signatures {
+					markSet[signatureDigest] = struct{}{}
+				}
+				break
+			case *schema2.DeserializedManifest:
+				config := manifest.(*schema2.DeserializedManifest).Config
+				markSet[config.Digest] = struct{}{}
+				break
+			}
+
+			return nil
+		})
+
+		return err
+	})
+
+	if err != nil {
+		return fmt.Errorf("failed to mark: %v\n", err)
+	}
+
+	// sweep
+	blobService := registry.Blobs()
+	deleteSet := make(map[digest.Digest]struct{})
+	err = blobService.Enumerate(ctx, func(dgst digest.Digest) error {
+		// check if digest is in markSet. If not, delete it!
+		if _, ok := markSet[dgst]; !ok {
+			deleteSet[dgst] = struct{}{}
+		}
+		return nil
+	})
+
+	// Construct vacuum
+	vacuum := storage.NewVacuum(ctx, storageDriver)
+	for dgst := range deleteSet {
+		err = vacuum.RemoveBlob(string(dgst))
+		if err != nil {
+			return fmt.Errorf("failed to delete blob %s: %v\n", dgst, err)
+		}
+	}
+
+	return err
+}
+
+// GCCmd is the cobra command that corresponds to the garbage-collect subcommand
+var GCCmd = &cobra.Command{
+	Use:   "garbage-collect <config>",
+	Short: "`garbage-collects` deletes layers not referenced by any manifests",
+	Long:  "`garbage-collects` deletes layers not referenced by any manifests",
+	Run: func(cmd *cobra.Command, args []string) {
+
+		config, err := resolveConfiguration(args)
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "configuration error: %v\n", err)
+			cmd.Usage()
+			os.Exit(1)
+		}
+
+		driver, err := factory.Create(config.Storage.Type(), config.Storage.Parameters())
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "failed to construct %s driver: %v", config.Storage.Type(), err)
+			os.Exit(1)
+		}
+
+		err = markAndSweep(driver)
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "failed to garbage collect: %v", err)
+			os.Exit(1)
+		}
+	},
+}

docs/garbagecollect_test.go

@@ -0,0 +1,343 @@
+package registry
+
+import (
+	"io"
+	"testing"
+
+	"github.com/docker/distribution"
+	"github.com/docker/distribution/context"
+	"github.com/docker/distribution/digest"
+	"github.com/docker/distribution/reference"
+	"github.com/docker/distribution/registry/storage"
+	"github.com/docker/distribution/registry/storage/driver"
+	"github.com/docker/distribution/registry/storage/driver/inmemory"
+	"github.com/docker/distribution/testutil"
+)
+
+type image struct {
+	manifest       distribution.Manifest
+	manifestDigest digest.Digest
+	layers         map[digest.Digest]io.ReadSeeker
+}
+
+func createRegistry(t *testing.T, driver driver.StorageDriver) distribution.Namespace {
+	ctx := context.Background()
+	registry, err := storage.NewRegistry(ctx, driver, storage.EnableDelete)
+	if err != nil {
+		t.Fatalf("Failed to construct namespace")
+	}
+	return registry
+}
+
+func makeRepository(t *testing.T, registry distribution.Namespace, name string) distribution.Repository {
+	ctx := context.Background()
+
+	// Initialize a dummy repository
+	named, err := reference.ParseNamed(name)
+	if err != nil {
+		t.Fatalf("Failed to parse name %s:  %v", name, err)
+	}
+
+	repo, err := registry.Repository(ctx, named)
+	if err != nil {
+		t.Fatalf("Failed to construct repository: %v", err)
+	}
+	return repo
+}
+
+func makeManifestService(t *testing.T, repository distribution.Repository) distribution.ManifestService {
+	ctx := context.Background()
+
+	manifestService, err := repository.Manifests(ctx)
+	if err != nil {
+		t.Fatalf("Failed to construct manifest store: %v", err)
+	}
+	return manifestService
+}
+
+func allBlobs(t *testing.T, registry distribution.Namespace) map[digest.Digest]struct{} {
+	ctx := context.Background()
+	blobService := registry.Blobs()
+	allBlobsMap := make(map[digest.Digest]struct{})
+	err := blobService.Enumerate(ctx, func(dgst digest.Digest) error {
+		allBlobsMap[dgst] = struct{}{}
+		return nil
+	})
+	if err != nil {
+		t.Fatalf("Error getting all blobs: %v", err)
+	}
+	return allBlobsMap
+}
+
+func uploadImage(t *testing.T, repository distribution.Repository, im image) digest.Digest {
+	// upload layers
+	err := testutil.UploadBlobs(repository, im.layers)
+	if err != nil {
+		t.Fatalf("layer upload failed: %v", err)
+	}
+
+	// upload manifest
+	ctx := context.Background()
+	manifestService := makeManifestService(t, repository)
+	manifestDigest, err := manifestService.Put(ctx, im.manifest)
+	if err != nil {
+		t.Fatalf("manifest upload failed: %v", err)
+	}
+
+	return manifestDigest
+}
+
+func uploadRandomSchema1Image(t *testing.T, repository distribution.Repository) image {
+	randomLayers, err := testutil.CreateRandomLayers(2)
+	if err != nil {
+		t.Fatalf("%v", err)
+	}
+
+	digests := []digest.Digest{}
+	for digest := range randomLayers {
+		digests = append(digests, digest)
+	}
+
+	manifest, err := testutil.MakeSchema1Manifest(digests)
+	if err != nil {
+		t.Fatalf("%v", err)
+	}
+
+	manifestDigest := uploadImage(t, repository, image{manifest: manifest, layers: randomLayers})
+	return image{
+		manifest:       manifest,
+		manifestDigest: manifestDigest,
+		layers:         randomLayers,
+	}
+}
+
+func uploadRandomSchema2Image(t *testing.T, repository distribution.Repository) image {
+	randomLayers, err := testutil.CreateRandomLayers(2)
+	if err != nil {
+		t.Fatalf("%v", err)
+	}
+
+	digests := []digest.Digest{}
+	for digest := range randomLayers {
+		digests = append(digests, digest)
+	}
+
+	manifest, err := testutil.MakeSchema2Manifest(repository, digests)
+	if err != nil {
+		t.Fatalf("%v", err)
+	}
+
+	manifestDigest := uploadImage(t, repository, image{manifest: manifest, layers: randomLayers})
+	return image{
+		manifest:       manifest,
+		manifestDigest: manifestDigest,
+		layers:         randomLayers,
+	}
+}
+
+func TestNoDeletionNoEffect(t *testing.T) {
+	ctx := context.Background()
+	inmemoryDriver := inmemory.New()
+
+	registry := createRegistry(t, inmemoryDriver)
+	repo := makeRepository(t, registry, "palailogos")
+	manifestService, err := repo.Manifests(ctx)
+
+	image1 := uploadRandomSchema1Image(t, repo)
+	image2 := uploadRandomSchema1Image(t, repo)
+	image3 := uploadRandomSchema2Image(t, repo)
+
+	// construct manifestlist for fun.
+	blobstatter := registry.BlobStatter()
+	manifestList, err := testutil.MakeManifestList(blobstatter, []digest.Digest{
+		image1.manifestDigest, image2.manifestDigest})
+	if err != nil {
+		t.Fatalf("Failed to make manifest list: %v", err)
+	}
+
+	_, err = manifestService.Put(ctx, manifestList)
+	if err != nil {
+		t.Fatalf("Failed to add manifest list: %v", err)
+	}
+
+	// Run GC
+	err = markAndSweep(inmemoryDriver)
+	if err != nil {
+		t.Fatalf("Failed mark and sweep: %v", err)
+	}
+
+	blobs := allBlobs(t, registry)
+
+	// the +1 at the end is for the manifestList
+	// the first +3 at the end for each manifest's blob
+	// the second +3 at the end for each manifest's signature/config layer
+	totalBlobCount := len(image1.layers) + len(image2.layers) + len(image3.layers) + 1 + 3 + 3
+	if len(blobs) != totalBlobCount {
+		t.Fatalf("Garbage collection affected storage")
+	}
+}
+
+func TestDeletionHasEffect(t *testing.T) {
+	ctx := context.Background()
+	inmemoryDriver := inmemory.New()
+
+	registry := createRegistry(t, inmemoryDriver)
+	repo := makeRepository(t, registry, "komnenos")
+	manifests, err := repo.Manifests(ctx)
+
+	image1 := uploadRandomSchema1Image(t, repo)
+	image2 := uploadRandomSchema1Image(t, repo)
+	image3 := uploadRandomSchema2Image(t, repo)
+
+	manifests.Delete(ctx, image2.manifestDigest)
+	manifests.Delete(ctx, image3.manifestDigest)
+
+	// Run GC
+	err = markAndSweep(inmemoryDriver)
+	if err != nil {
+		t.Fatalf("Failed mark and sweep: %v", err)
+	}
+
+	blobs := allBlobs(t, registry)
+
+	// check that the image1 manifest and all the layers are still in blobs
+	if _, ok := blobs[image1.manifestDigest]; !ok {
+		t.Fatalf("First manifest is missing")
+	}
+
+	for layer := range image1.layers {
+		if _, ok := blobs[layer]; !ok {
+			t.Fatalf("manifest 1 layer is missing: %v", layer)
+		}
+	}
+
+	// check that image2 and image3 layers are not still around
+	for layer := range image2.layers {
+		if _, ok := blobs[layer]; ok {
+			t.Fatalf("manifest 2 layer is present: %v", layer)
+		}
+	}
+
+	for layer := range image3.layers {
+		if _, ok := blobs[layer]; ok {
+			t.Fatalf("manifest 3 layer is present: %v", layer)
+		}
+	}
+}
+
+func getAnyKey(digests map[digest.Digest]io.ReadSeeker) (d digest.Digest) {
+	for d = range digests {
+		break
+	}
+	return
+}
+
+func getKeys(digests map[digest.Digest]io.ReadSeeker) (ds []digest.Digest) {
+	for d := range digests {
+		ds = append(ds, d)
+	}
+	return
+}
+
+func TestDeletionWithSharedLayer(t *testing.T) {
+	ctx := context.Background()
+	inmemoryDriver := inmemory.New()
+
+	registry := createRegistry(t, inmemoryDriver)
+	repo := makeRepository(t, registry, "tzimiskes")
+
+	// Create random layers
+	randomLayers1, err := testutil.CreateRandomLayers(3)
+	if err != nil {
+		t.Fatalf("failed to make layers: %v", err)
+	}
+
+	randomLayers2, err := testutil.CreateRandomLayers(3)
+	if err != nil {
+		t.Fatalf("failed to make layers: %v", err)
+	}
+
+	// Upload all layers
+	err = testutil.UploadBlobs(repo, randomLayers1)
+	if err != nil {
+		t.Fatalf("failed to upload layers: %v", err)
+	}
+
+	err = testutil.UploadBlobs(repo, randomLayers2)
+	if err != nil {
+		t.Fatalf("failed to upload layers: %v", err)
+	}
+
+	// Construct manifests
+	manifest1, err := testutil.MakeSchema1Manifest(getKeys(randomLayers1))
+	if err != nil {
+		t.Fatalf("failed to make manifest: %v", err)
+	}
+
+	sharedKey := getAnyKey(randomLayers1)
+	manifest2, err := testutil.MakeSchema2Manifest(repo, append(getKeys(randomLayers2), sharedKey))
+	if err != nil {
+		t.Fatalf("failed to make manifest: %v", err)
+	}
+
+	manifestService := makeManifestService(t, repo)
+
+	// Upload manifests
+	_, err = manifestService.Put(ctx, manifest1)
+	if err != nil {
+		t.Fatalf("manifest upload failed: %v", err)
+	}
+
+	manifestDigest2, err := manifestService.Put(ctx, manifest2)
+	if err != nil {
+		t.Fatalf("manifest upload failed: %v", err)
+	}
+
+	// delete
+	err = manifestService.Delete(ctx, manifestDigest2)
+	if err != nil {
+		t.Fatalf("manifest deletion failed: %v", err)
+	}
+
+	// check that all of the layers in layer 1 are still there
+	blobs := allBlobs(t, registry)
+	for dgst := range randomLayers1 {
+		if _, ok := blobs[dgst]; !ok {
+			t.Fatalf("random layer 1 blob missing: %v", dgst)
+		}
+	}
+}
+
+func TestOrphanBlobDeleted(t *testing.T) {
+	inmemoryDriver := inmemory.New()
+
+	registry := createRegistry(t, inmemoryDriver)
+	repo := makeRepository(t, registry, "michael_z_doukas")
+
+	digests, err := testutil.CreateRandomLayers(1)
+	if err != nil {
+		t.Fatalf("Failed to create random digest: %v", err)
+	}
+
+	if err = testutil.UploadBlobs(repo, digests); err != nil {
+		t.Fatalf("Failed to upload blob: %v", err)
+	}
+
+	// formality to create the necessary directories
+	uploadRandomSchema2Image(t, repo)
+
+	// Run GC
+	err = markAndSweep(inmemoryDriver)
+	if err != nil {
+		t.Fatalf("Failed mark and sweep: %v", err)
+	}
+
+	blobs := allBlobs(t, registry)
+
+	// check that orphan blob layers are not still around
+	for dgst := range digests {
+		if _, ok := blobs[dgst]; ok {
+			t.Fatalf("Orphan layer is present: %v", dgst)
+		}
+	}
+}

docs/proxy/proxymanifeststore.go

@@ -93,8 +93,3 @@ func (pms proxyManifestStore) Put(ctx context.Context, manifest distribution.Man
 func (pms proxyManifestStore) Delete(ctx context.Context, dgst digest.Digest) error {
 	return distribution.ErrUnsupported
 }
-
-/*func (pms proxyManifestStore) Enumerate(ctx context.Context, manifests []distribution.Manifest, last distribution.Manifest) (n int, err error) {
-	return 0, distribution.ErrUnsupported
-}
-*/

docs/proxy/proxyregistry.go

@@ -166,6 +166,14 @@ func (pr *proxyingRegistry) Repository(ctx context.Context, name reference.Named
 	}, nil
 }
 
+func (pr *proxyingRegistry) Blobs() distribution.BlobEnumerator {
+	return pr.embedded.Blobs()
+}
+
+func (pr *proxyingRegistry) BlobStatter() distribution.BlobStatter {
+	return pr.embedded.BlobStatter()
+}
+
 // authChallenger encapsulates a request to the upstream to establish credential challenges
 type authChallenger interface {
 	tryEstablishChallenges(context.Context) error

docs/registry.go

@@ -24,16 +24,12 @@ import (
 	"github.com/yvasiyarov/gorelic"
 )
 
-// Cmd is a cobra command for running the registry.
+// ServeCmd is a cobra command for running the registry.
-var Cmd = &cobra.Command{
+var ServeCmd = &cobra.Command{
-	Use:   "registry <config>",
+	Use:   "serve <config>",
-	Short: "registry stores and distributes Docker images",
+	Short: "`serve` stores and distributes Docker images",
-	Long:  "registry stores and distributes Docker images.",
+	Long:  "`serve` stores and distributes Docker images.",
 	Run: func(cmd *cobra.Command, args []string) {
-		if showVersion {
-			version.PrintVersion()
-			return
-		}
 
 		// setup context
 		ctx := context.WithVersion(context.Background(), version.Version)
@@ -65,12 +61,6 @@ var Cmd = &cobra.Command{
 	},
 }
 
-var showVersion bool
-
-func init() {
-	Cmd.PersistentFlags().BoolVarP(&showVersion, "version", "v", false, "show the version and exit")
-}
-
 // A Registry represents a complete instance of the registry.
 // TODO(aaronl): It might make sense for Registry to become an interface.
 type Registry struct {

docs/root.go

@@ -0,0 +1,28 @@
+package registry
+
+import (
+	"github.com/docker/distribution/version"
+	"github.com/spf13/cobra"
+)
+
+var showVersion bool
+
+func init() {
+	RootCmd.AddCommand(ServeCmd)
+	RootCmd.AddCommand(GCCmd)
+	RootCmd.Flags().BoolVarP(&showVersion, "version", "v", false, "show the version and exit")
+}
+
+// RootCmd is the main command for the 'registry' binary.
+var RootCmd = &cobra.Command{
+	Use:   "registry",
+	Short: "`registry`",
+	Long:  "`registry`",
+	Run: func(cmd *cobra.Command, args []string) {
+		if showVersion {
+			version.PrintVersion()
+			return
+		}
+		cmd.Usage()
+	},
+}

docs/storage/blobstore.go

@@ -1,6 +1,8 @@
 package storage
 
 import (
+	"path"
+
 	"github.com/docker/distribution"
 	"github.com/docker/distribution/context"
 	"github.com/docker/distribution/digest"
@@ -85,6 +87,36 @@ func (bs *blobStore) Put(ctx context.Context, mediaType string, p []byte) (distr
 	}, bs.driver.PutContent(ctx, bp, p)
 }
 
+func (bs *blobStore) Enumerate(ctx context.Context, ingester func(dgst digest.Digest) error) error {
+
+	specPath, err := pathFor(blobsPathSpec{})
+	if err != nil {
+		return err
+	}
+
+	err = Walk(ctx, bs.driver, specPath, func(fileInfo driver.FileInfo) error {
+		// skip directories
+		if fileInfo.IsDir() {
+			return nil
+		}
+
+		currentPath := fileInfo.Path()
+		// we only want to parse paths that end with /data
+		_, fileName := path.Split(currentPath)
+		if fileName != "data" {
+			return nil
+		}
+
+		digest, err := digestFromPath(currentPath)
+		if err != nil {
+			return err
+		}
+
+		return ingester(digest)
+	})
+	return err
+}
+
 // path returns the canonical path for the blob identified by digest. The blob
 // may or may not exist.
 func (bs *blobStore) path(dgst digest.Digest) (string, error) {

docs/storage/catalog.go

@@ -64,3 +64,34 @@ func (reg *registry) Repositories(ctx context.Context, repos []string, last stri
 
 	return n, errVal
 }
+
+// Enumerate applies ingester to each repository
+func (reg *registry) Enumerate(ctx context.Context, ingester func(string) error) error {
+	repoNameBuffer := make([]string, 100)
+	var last string
+	for {
+		n, err := reg.Repositories(ctx, repoNameBuffer, last)
+		if err != nil && err != io.EOF {
+			return err
+		}
+
+		if n == 0 {
+			break
+		}
+
+		last = repoNameBuffer[n-1]
+		for i := 0; i < n; i++ {
+			repoName := repoNameBuffer[i]
+			err = ingester(repoName)
+			if err != nil {
+				return err
+			}
+		}
+
+		if err == io.EOF {
+			break
+		}
+	}
+	return nil
+
+}

docs/storage/linkedblobstore.go

@@ -3,6 +3,7 @@ package storage
 import (
 	"fmt"
 	"net/http"
+	"path"
 	"time"
 
 	"github.com/docker/distribution"
@@ -37,6 +38,9 @@ type linkedBlobStore struct {
 	// removed an the blob links folder should be merged. The first entry is
 	// treated as the "canonical" link location and will be used for writes.
 	linkPathFns []linkPathFunc
+
+	// linkDirectoryPathSpec locates the root directories in which one might find links
+	linkDirectoryPathSpec pathSpec
 }
 
 var _ distribution.BlobStore = &linkedBlobStore{}
@@ -236,6 +240,55 @@ func (lbs *linkedBlobStore) Delete(ctx context.Context, dgst digest.Digest) erro
 	return nil
 }
 
+func (lbs *linkedBlobStore) Enumerate(ctx context.Context, ingestor func(digest.Digest) error) error {
+	rootPath, err := pathFor(lbs.linkDirectoryPathSpec)
+	if err != nil {
+		return err
+	}
+	err = Walk(ctx, lbs.blobStore.driver, rootPath, func(fileInfo driver.FileInfo) error {
+		// exit early if directory...
+		if fileInfo.IsDir() {
+			return nil
+		}
+		filePath := fileInfo.Path()
+
+		// check if it's a link
+		_, fileName := path.Split(filePath)
+		if fileName != "link" {
+			return nil
+		}
+
+		// read the digest found in link
+		digest, err := lbs.blobStore.readlink(ctx, filePath)
+		if err != nil {
+			return err
+		}
+
+		// ensure this conforms to the linkPathFns
+		_, err = lbs.Stat(ctx, digest)
+		if err != nil {
+			// we expect this error to occur so we move on
+			if err == distribution.ErrBlobUnknown {
+				return nil
+			}
+			return err
+		}
+
+		err = ingestor(digest)
+		if err != nil {
+			return err
+		}
+
+		return nil
+	})
+
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
 func (lbs *linkedBlobStore) mount(ctx context.Context, sourceRepo reference.Named, dgst digest.Digest) (distribution.Descriptor, error) {
 	repo, err := lbs.registry.Repository(ctx, sourceRepo)
 	if err != nil {

docs/storage/manifeststore.go

@@ -2,6 +2,7 @@ package storage
 
 import (
 	"fmt"
+	"path"
 
 	"encoding/json"
 	"github.com/docker/distribution"
@@ -129,6 +130,52 @@ func (ms *manifestStore) Delete(ctx context.Context, dgst digest.Digest) error {
 	return ms.blobStore.Delete(ctx, dgst)
 }
 
-func (ms *manifestStore) Enumerate(ctx context.Context, manifests []distribution.Manifest, last distribution.Manifest) (n int, err error) {
+func (ms *manifestStore) Enumerate(ctx context.Context, ingester func(digest.Digest) error) error {
-	return 0, distribution.ErrUnsupported
+	err := ms.blobStore.Enumerate(ctx, func(dgst digest.Digest) error {
+		err := ingester(dgst)
+		if err != nil {
+			return err
+		}
+		return nil
+	})
+	return err
+}
+
+// Only valid for schema1 signed manifests
+func (ms *manifestStore) GetSignatures(ctx context.Context, manifestDigest digest.Digest) ([]digest.Digest, error) {
+	// sanity check that digest refers to a schema1 digest
+	manifest, err := ms.Get(ctx, manifestDigest)
+	if err != nil {
+		return nil, err
+	}
+
+	if _, ok := manifest.(*schema1.SignedManifest); !ok {
+		return nil, fmt.Errorf("digest %v is not for schema1 manifest", manifestDigest)
+	}
+
+	signaturesPath, err := pathFor(manifestSignaturesPathSpec{
+		name:     ms.repository.Named().Name(),
+		revision: manifestDigest,
+	})
+	if err != nil {
+		return nil, err
+	}
+
+	signaturesPath = path.Join(signaturesPath, "sha256")
+
+	signaturePaths, err := ms.blobStore.driver.List(ctx, signaturesPath)
+	if err != nil {
+		return nil, err
+	}
+
+	var digests []digest.Digest
+	for _, sigPath := range signaturePaths {
+		sigdigest, err := digest.ParseDigest("sha256:" + path.Base(sigPath))
+		if err != nil {
+			// merely found not a digest
+			continue
+		}
+		digests = append(digests, sigdigest)
+	}
+	return digests, nil
 }

docs/storage/paths.go

@@ -74,6 +74,7 @@ const (
 //
 //	Manifests:
 //
+// 	manifestRevisionsPathSpec:      <root>/v2/repositories/<name>/_manifests/revisions/
 // 	manifestRevisionPathSpec:      <root>/v2/repositories/<name>/_manifests/revisions/<algorithm>/<hex digest>/
 // 	manifestRevisionLinkPathSpec:  <root>/v2/repositories/<name>/_manifests/revisions/<algorithm>/<hex digest>/link
 // 	manifestSignaturesPathSpec:    <root>/v2/repositories/<name>/_manifests/revisions/<algorithm>/<hex digest>/signatures/
@@ -100,6 +101,7 @@ const (
 //
 //	Blob Store:
 //
+//	blobsPathSpec:                  <root>/v2/blobs/
 // 	blobPathSpec:                   <root>/v2/blobs/<algorithm>/<first two hex bytes of digest>/<hex digest>
 // 	blobDataPathSpec:               <root>/v2/blobs/<algorithm>/<first two hex bytes of digest>/<hex digest>/data
 // 	blobMediaTypePathSpec:               <root>/v2/blobs/<algorithm>/<first two hex bytes of digest>/<hex digest>/data
@@ -125,6 +127,9 @@ func pathFor(spec pathSpec) (string, error) {
 
 	switch v := spec.(type) {
 
+	case manifestRevisionsPathSpec:
+		return path.Join(append(repoPrefix, v.name, "_manifests", "revisions")...), nil
+
 	case manifestRevisionPathSpec:
 		components, err := digestPathComponents(v.revision, false)
 		if err != nil {
@@ -246,6 +251,17 @@ func pathFor(spec pathSpec) (string, error) {
 		blobLinkPathComponents := append(repoPrefix, v.name, "_layers")
 
 		return path.Join(path.Join(append(blobLinkPathComponents, components...)...), "link"), nil
+	case blobsPathSpec:
+		blobsPathPrefix := append(rootPrefix, "blobs")
+		return path.Join(blobsPathPrefix...), nil
+	case blobPathSpec:
+		components, err := digestPathComponents(v.digest, true)
+		if err != nil {
+			return "", err
+		}
+
+		blobPathPrefix := append(rootPrefix, "blobs")
+		return path.Join(append(blobPathPrefix, components...)...), nil
 	case blobDataPathSpec:
 		components, err := digestPathComponents(v.digest, true)
 		if err != nil {
@@ -281,6 +297,14 @@ type pathSpec interface {
 	pathSpec()
 }
 
+// manifestRevisionsPathSpec describes the directory path for
+// a manifest revision.
+type manifestRevisionsPathSpec struct {
+	name string
+}
+
+func (manifestRevisionsPathSpec) pathSpec() {}
+
 // manifestRevisionPathSpec describes the components of the directory path for
 // a manifest revision.
 type manifestRevisionPathSpec struct {
@@ -404,12 +428,17 @@ var blobAlgorithmReplacer = strings.NewReplacer(
 	";", "/",
 )
 
-// // blobPathSpec contains the path for the registry global blob store.
+// blobsPathSpec contains the path for the blobs directory
-// type blobPathSpec struct {
+type blobsPathSpec struct{}
-// 	digest digest.Digest
-// }
 
-// func (blobPathSpec) pathSpec() {}
+func (blobsPathSpec) pathSpec() {}
+
+// blobPathSpec contains the path for the registry global blob store.
+type blobPathSpec struct {
+	digest digest.Digest
+}
+
+func (blobPathSpec) pathSpec() {}
 
 // blobDataPathSpec contains the path for the registry global blob store. For
 // now, this contains layer data, exclusively.
@@ -491,3 +520,23 @@ func digestPathComponents(dgst digest.Digest, multilevel bool) ([]string, error)
 
 	return append(prefix, suffix...), nil
 }
+
+// Reconstructs a digest from a path
+func digestFromPath(digestPath string) (digest.Digest, error) {
+
+	digestPath = strings.TrimSuffix(digestPath, "/data")
+	dir, hex := path.Split(digestPath)
+	dir = path.Dir(dir)
+	dir, next := path.Split(dir)
+
+	// next is either the algorithm OR the first two characters in the hex string
+	var algo string
+	if next == hex[:2] {
+		algo = path.Base(dir)
+	} else {
+		algo = next
+	}
+
+	dgst := digest.NewDigestFromHex(algo, hex)
+	return dgst, dgst.Validate()
+}

docs/storage/paths_test.go

@@ -2,6 +2,8 @@ package storage
 
 import (
 	"testing"
+
+	"github.com/docker/distribution/digest"
 )
 
 func TestPathMapper(t *testing.T) {
@@ -120,3 +122,29 @@ func TestPathMapper(t *testing.T) {
 	}
 
 }
+
+func TestDigestFromPath(t *testing.T) {
+	for _, testcase := range []struct {
+		path       string
+		expected   digest.Digest
+		multilevel bool
+		err        error
+	}{
+		{
+			path:       "/docker/registry/v2/blobs/sha256/99/9943fffae777400c0344c58869c4c2619c329ca3ad4df540feda74d291dd7c86/data",
+			multilevel: true,
+			expected:   "sha256:9943fffae777400c0344c58869c4c2619c329ca3ad4df540feda74d291dd7c86",
+			err:        nil,
+		},
+	} {
+		result, err := digestFromPath(testcase.path)
+		if err != testcase.err {
+			t.Fatalf("Unexpected error value %v when we wanted %v", err, testcase.err)
+		}
+
+		if result != testcase.expected {
+			t.Fatalf("Unexpected result value %v when we wanted %v", result, testcase.expected)
+
+		}
+	}
+}

docs/storage/registry.go

@@ -147,6 +147,14 @@ func (reg *registry) Repository(ctx context.Context, canonicalName reference.Nam
 	}, nil
 }
 
+func (reg *registry) Blobs() distribution.BlobEnumerator {
+	return reg.blobStore
+}
+
+func (reg *registry) BlobStatter() distribution.BlobStatter {
+	return reg.statter
+}
+
 // repository provides name-scoped access to various services.
 type repository struct {
 	*registry
@@ -180,6 +188,8 @@ func (repo *repository) Manifests(ctx context.Context, options ...distribution.M
 		blobLinkPath,
 	}
 
+	manifestDirectoryPathSpec := manifestRevisionsPathSpec{name: repo.name.Name()}
+
 	blobStore := &linkedBlobStore{
 		ctx:           ctx,
 		blobStore:     repo.blobStore,
@@ -193,7 +203,8 @@ func (repo *repository) Manifests(ctx context.Context, options ...distribution.M
 
 		// TODO(stevvooe): linkPath limits this blob store to only
 		// manifests. This instance cannot be used for blob checks.
-		linkPathFns: manifestLinkPathFns,
+		linkPathFns:           manifestLinkPathFns,
+		linkDirectoryPathSpec: manifestDirectoryPathSpec,
 	}
 
 	ms := &manifestStore{

docs/storage/vacuum.go

@@ -34,11 +34,13 @@ func (v Vacuum) RemoveBlob(dgst string) error {
 		return err
 	}
 
-	blobPath, err := pathFor(blobDataPathSpec{digest: d})
+	blobPath, err := pathFor(blobPathSpec{digest: d})
 	if err != nil {
 		return err
 	}
+
 	context.GetLogger(v.ctx).Infof("Deleting blob: %s", blobPath)
+
 	err = v.driver.Delete(v.ctx, blobPath)
 	if err != nil {
 		return err