move dependencies to vendor

vendor/github.com/docker/distribution/registry/storage/cache/cache.go

@@ -0,0 +1,35 @@
+// Package cache provides facilities to speed up access to the storage
+// backend.
+package cache
+
+import (
+	"fmt"
+
+	"github.com/docker/distribution"
+)
+
+// BlobDescriptorCacheProvider provides repository scoped
+// BlobDescriptorService cache instances and a global descriptor cache.
+type BlobDescriptorCacheProvider interface {
+	distribution.BlobDescriptorService
+
+	RepositoryScoped(repo string) (distribution.BlobDescriptorService, error)
+}
+
+// ValidateDescriptor provides a helper function to ensure that caches have
+// common criteria for admitting descriptors.
+func ValidateDescriptor(desc distribution.Descriptor) error {
+	if err := desc.Digest.Validate(); err != nil {
+		return err
+	}
+
+	if desc.Size < 0 {
+		return fmt.Errorf("cache: invalid length in descriptor: %v < 0", desc.Size)
+	}
+
+	if desc.MediaType == "" {
+		return fmt.Errorf("cache: empty mediatype on descriptor: %v", desc)
+	}
+
+	return nil
+}

vendor/github.com/docker/distribution/registry/storage/cache/cachedblobdescriptorstore.go

@@ -0,0 +1,101 @@
+package cache
+
+import (
+	"github.com/docker/distribution/context"
+	"github.com/docker/distribution/digest"
+
+	"github.com/docker/distribution"
+)
+
+// Metrics is used to hold metric counters
+// related to the number of times a cache was
+// hit or missed.
+type Metrics struct {
+	Requests uint64
+	Hits     uint64
+	Misses   uint64
+}
+
+// MetricsTracker represents a metric tracker
+// which simply counts the number of hits and misses.
+type MetricsTracker interface {
+	Hit()
+	Miss()
+	Metrics() Metrics
+}
+
+type cachedBlobStatter struct {
+	cache   distribution.BlobDescriptorService
+	backend distribution.BlobDescriptorService
+	tracker MetricsTracker
+}
+
+// NewCachedBlobStatter creates a new statter which prefers a cache and
+// falls back to a backend.
+func NewCachedBlobStatter(cache distribution.BlobDescriptorService, backend distribution.BlobDescriptorService) distribution.BlobDescriptorService {
+	return &cachedBlobStatter{
+		cache:   cache,
+		backend: backend,
+	}
+}
+
+// NewCachedBlobStatterWithMetrics creates a new statter which prefers a cache and
+// falls back to a backend. Hits and misses will send to the tracker.
+func NewCachedBlobStatterWithMetrics(cache distribution.BlobDescriptorService, backend distribution.BlobDescriptorService, tracker MetricsTracker) distribution.BlobStatter {
+	return &cachedBlobStatter{
+		cache:   cache,
+		backend: backend,
+		tracker: tracker,
+	}
+}
+
+func (cbds *cachedBlobStatter) Stat(ctx context.Context, dgst digest.Digest) (distribution.Descriptor, error) {
+	desc, err := cbds.cache.Stat(ctx, dgst)
+	if err != nil {
+		if err != distribution.ErrBlobUnknown {
+			context.GetLogger(ctx).Errorf("error retrieving descriptor from cache: %v", err)
+		}
+
+		goto fallback
+	}
+
+	if cbds.tracker != nil {
+		cbds.tracker.Hit()
+	}
+	return desc, nil
+fallback:
+	if cbds.tracker != nil {
+		cbds.tracker.Miss()
+	}
+	desc, err = cbds.backend.Stat(ctx, dgst)
+	if err != nil {
+		return desc, err
+	}
+
+	if err := cbds.cache.SetDescriptor(ctx, dgst, desc); err != nil {
+		context.GetLogger(ctx).Errorf("error adding descriptor %v to cache: %v", desc.Digest, err)
+	}
+
+	return desc, err
+
+}
+
+func (cbds *cachedBlobStatter) Clear(ctx context.Context, dgst digest.Digest) error {
+	err := cbds.cache.Clear(ctx, dgst)
+	if err != nil {
+		return err
+	}
+
+	err = cbds.backend.Clear(ctx, dgst)
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
+func (cbds *cachedBlobStatter) SetDescriptor(ctx context.Context, dgst digest.Digest, desc distribution.Descriptor) error {
+	if err := cbds.cache.SetDescriptor(ctx, dgst, desc); err != nil {
+		context.GetLogger(ctx).Errorf("error adding descriptor %v to cache: %v", desc.Digest, err)
+	}
+	return nil
+}

vendor/github.com/docker/distribution/registry/storage/cache/memory/memory.go

@@ -0,0 +1,170 @@
+package memory
+
+import (
+	"sync"
+
+	"github.com/docker/distribution"
+	"github.com/docker/distribution/context"
+	"github.com/docker/distribution/digest"
+	"github.com/docker/distribution/registry/api/v2"
+	"github.com/docker/distribution/registry/storage/cache"
+)
+
+type inMemoryBlobDescriptorCacheProvider struct {
+	global       *mapBlobDescriptorCache
+	repositories map[string]*mapBlobDescriptorCache
+	mu           sync.RWMutex
+}
+
+// NewInMemoryBlobDescriptorCacheProvider returns a new mapped-based cache for
+// storing blob descriptor data.
+func NewInMemoryBlobDescriptorCacheProvider() cache.BlobDescriptorCacheProvider {
+	return &inMemoryBlobDescriptorCacheProvider{
+		global:       newMapBlobDescriptorCache(),
+		repositories: make(map[string]*mapBlobDescriptorCache),
+	}
+}
+
+func (imbdcp *inMemoryBlobDescriptorCacheProvider) RepositoryScoped(repo string) (distribution.BlobDescriptorService, error) {
+	if err := v2.ValidateRepositoryName(repo); err != nil {
+		return nil, err
+	}
+
+	imbdcp.mu.RLock()
+	defer imbdcp.mu.RUnlock()
+
+	return &repositoryScopedInMemoryBlobDescriptorCache{
+		repo:       repo,
+		parent:     imbdcp,
+		repository: imbdcp.repositories[repo],
+	}, nil
+}
+
+func (imbdcp *inMemoryBlobDescriptorCacheProvider) Stat(ctx context.Context, dgst digest.Digest) (distribution.Descriptor, error) {
+	return imbdcp.global.Stat(ctx, dgst)
+}
+
+func (imbdcp *inMemoryBlobDescriptorCacheProvider) Clear(ctx context.Context, dgst digest.Digest) error {
+	return imbdcp.global.Clear(ctx, dgst)
+}
+
+func (imbdcp *inMemoryBlobDescriptorCacheProvider) SetDescriptor(ctx context.Context, dgst digest.Digest, desc distribution.Descriptor) error {
+	_, err := imbdcp.Stat(ctx, dgst)
+	if err == distribution.ErrBlobUnknown {
+
+		if dgst.Algorithm() != desc.Digest.Algorithm() && dgst != desc.Digest {
+			// if the digests differ, set the other canonical mapping
+			if err := imbdcp.global.SetDescriptor(ctx, desc.Digest, desc); err != nil {
+				return err
+			}
+		}
+
+		// unknown, just set it
+		return imbdcp.global.SetDescriptor(ctx, dgst, desc)
+	}
+
+	// we already know it, do nothing
+	return err
+}
+
+// repositoryScopedInMemoryBlobDescriptorCache provides the request scoped
+// repository cache. Instances are not thread-safe but the delegated
+// operations are.
+type repositoryScopedInMemoryBlobDescriptorCache struct {
+	repo       string
+	parent     *inMemoryBlobDescriptorCacheProvider // allows lazy allocation of repo's map
+	repository *mapBlobDescriptorCache
+}
+
+func (rsimbdcp *repositoryScopedInMemoryBlobDescriptorCache) Stat(ctx context.Context, dgst digest.Digest) (distribution.Descriptor, error) {
+	if rsimbdcp.repository == nil {
+		return distribution.Descriptor{}, distribution.ErrBlobUnknown
+	}
+
+	return rsimbdcp.repository.Stat(ctx, dgst)
+}
+
+func (rsimbdcp *repositoryScopedInMemoryBlobDescriptorCache) Clear(ctx context.Context, dgst digest.Digest) error {
+	if rsimbdcp.repository == nil {
+		return distribution.ErrBlobUnknown
+	}
+
+	return rsimbdcp.repository.Clear(ctx, dgst)
+}
+
+func (rsimbdcp *repositoryScopedInMemoryBlobDescriptorCache) SetDescriptor(ctx context.Context, dgst digest.Digest, desc distribution.Descriptor) error {
+	if rsimbdcp.repository == nil {
+		// allocate map since we are setting it now.
+		rsimbdcp.parent.mu.Lock()
+		var ok bool
+		// have to read back value since we may have allocated elsewhere.
+		rsimbdcp.repository, ok = rsimbdcp.parent.repositories[rsimbdcp.repo]
+		if !ok {
+			rsimbdcp.repository = newMapBlobDescriptorCache()
+			rsimbdcp.parent.repositories[rsimbdcp.repo] = rsimbdcp.repository
+		}
+
+		rsimbdcp.parent.mu.Unlock()
+	}
+
+	if err := rsimbdcp.repository.SetDescriptor(ctx, dgst, desc); err != nil {
+		return err
+	}
+
+	return rsimbdcp.parent.SetDescriptor(ctx, dgst, desc)
+}
+
+// mapBlobDescriptorCache provides a simple map-based implementation of the
+// descriptor cache.
+type mapBlobDescriptorCache struct {
+	descriptors map[digest.Digest]distribution.Descriptor
+	mu          sync.RWMutex
+}
+
+var _ distribution.BlobDescriptorService = &mapBlobDescriptorCache{}
+
+func newMapBlobDescriptorCache() *mapBlobDescriptorCache {
+	return &mapBlobDescriptorCache{
+		descriptors: make(map[digest.Digest]distribution.Descriptor),
+	}
+}
+
+func (mbdc *mapBlobDescriptorCache) Stat(ctx context.Context, dgst digest.Digest) (distribution.Descriptor, error) {
+	if err := dgst.Validate(); err != nil {
+		return distribution.Descriptor{}, err
+	}
+
+	mbdc.mu.RLock()
+	defer mbdc.mu.RUnlock()
+
+	desc, ok := mbdc.descriptors[dgst]
+	if !ok {
+		return distribution.Descriptor{}, distribution.ErrBlobUnknown
+	}
+
+	return desc, nil
+}
+
+func (mbdc *mapBlobDescriptorCache) Clear(ctx context.Context, dgst digest.Digest) error {
+	mbdc.mu.Lock()
+	defer mbdc.mu.Unlock()
+
+	delete(mbdc.descriptors, dgst)
+	return nil
+}
+
+func (mbdc *mapBlobDescriptorCache) SetDescriptor(ctx context.Context, dgst digest.Digest, desc distribution.Descriptor) error {
+	if err := dgst.Validate(); err != nil {
+		return err
+	}
+
+	if err := cache.ValidateDescriptor(desc); err != nil {
+		return err
+	}
+
+	mbdc.mu.Lock()
+	defer mbdc.mu.Unlock()
+
+	mbdc.descriptors[dgst] = desc
+	return nil
+}

vendor/github.com/docker/distribution/registry/storage/cache/memory/memory_test.go

@@ -0,0 +1,13 @@
+package memory
+
+import (
+	"testing"
+
+	"github.com/docker/distribution/registry/storage/cache"
+)
+
+// TestInMemoryBlobInfoCache checks the in memory implementation is working
+// correctly.
+func TestInMemoryBlobInfoCache(t *testing.T) {
+	cache.CheckBlobDescriptorCache(t, NewInMemoryBlobDescriptorCacheProvider())
+}

vendor/github.com/docker/distribution/registry/storage/cache/redis/redis.go

@@ -0,0 +1,268 @@
+package redis
+
+import (
+	"fmt"
+
+	"github.com/docker/distribution"
+	"github.com/docker/distribution/context"
+	"github.com/docker/distribution/digest"
+	"github.com/docker/distribution/registry/api/v2"
+	"github.com/docker/distribution/registry/storage/cache"
+	"github.com/garyburd/redigo/redis"
+)
+
+// redisBlobStatService provides an implementation of
+// BlobDescriptorCacheProvider based on redis. Blob descriptors are stored in
+// two parts. The first provide fast access to repository membership through a
+// redis set for each repo. The second is a redis hash keyed by the digest of
+// the layer, providing path, length and mediatype information. There is also
+// a per-repository redis hash of the blob descriptor, allowing override of
+// data. This is currently used to override the mediatype on a per-repository
+// basis.
+//
+// Note that there is no implied relationship between these two caches. The
+// layer may exist in one, both or none and the code must be written this way.
+type redisBlobDescriptorService struct {
+	pool *redis.Pool
+
+	// TODO(stevvooe): We use a pool because we don't have great control over
+	// the cache lifecycle to manage connections. A new connection if fetched
+	// for each operation. Once we have better lifecycle management of the
+	// request objects, we can change this to a connection.
+}
+
+// NewRedisBlobDescriptorCacheProvider returns a new redis-based
+// BlobDescriptorCacheProvider using the provided redis connection pool.
+func NewRedisBlobDescriptorCacheProvider(pool *redis.Pool) cache.BlobDescriptorCacheProvider {
+	return &redisBlobDescriptorService{
+		pool: pool,
+	}
+}
+
+// RepositoryScoped returns the scoped cache.
+func (rbds *redisBlobDescriptorService) RepositoryScoped(repo string) (distribution.BlobDescriptorService, error) {
+	if err := v2.ValidateRepositoryName(repo); err != nil {
+		return nil, err
+	}
+
+	return &repositoryScopedRedisBlobDescriptorService{
+		repo:     repo,
+		upstream: rbds,
+	}, nil
+}
+
+// Stat retrieves the descriptor data from the redis hash entry.
+func (rbds *redisBlobDescriptorService) Stat(ctx context.Context, dgst digest.Digest) (distribution.Descriptor, error) {
+	if err := dgst.Validate(); err != nil {
+		return distribution.Descriptor{}, err
+	}
+
+	conn := rbds.pool.Get()
+	defer conn.Close()
+
+	return rbds.stat(ctx, conn, dgst)
+}
+
+func (rbds *redisBlobDescriptorService) Clear(ctx context.Context, dgst digest.Digest) error {
+	if err := dgst.Validate(); err != nil {
+		return err
+	}
+
+	conn := rbds.pool.Get()
+	defer conn.Close()
+
+	// Not atomic in redis <= 2.3
+	reply, err := conn.Do("HDEL", rbds.blobDescriptorHashKey(dgst), "digest", "length", "mediatype")
+	if err != nil {
+		return err
+	}
+
+	if reply == 0 {
+		return distribution.ErrBlobUnknown
+	}
+
+	return nil
+}
+
+// stat provides an internal stat call that takes a connection parameter. This
+// allows some internal management of the connection scope.
+func (rbds *redisBlobDescriptorService) stat(ctx context.Context, conn redis.Conn, dgst digest.Digest) (distribution.Descriptor, error) {
+	reply, err := redis.Values(conn.Do("HMGET", rbds.blobDescriptorHashKey(dgst), "digest", "size", "mediatype"))
+	if err != nil {
+		return distribution.Descriptor{}, err
+	}
+
+	// NOTE(stevvooe): The "size" field used to be "length". We treat a
+	// missing "size" field here as an unknown blob, which causes a cache
+	// miss, effectively migrating the field.
+	if len(reply) < 3 || reply[0] == nil || reply[1] == nil { // don't care if mediatype is nil
+		return distribution.Descriptor{}, distribution.ErrBlobUnknown
+	}
+
+	var desc distribution.Descriptor
+	if _, err := redis.Scan(reply, &desc.Digest, &desc.Size, &desc.MediaType); err != nil {
+		return distribution.Descriptor{}, err
+	}
+
+	return desc, nil
+}
+
+// SetDescriptor sets the descriptor data for the given digest using a redis
+// hash. A hash is used here since we may store unrelated fields about a layer
+// in the future.
+func (rbds *redisBlobDescriptorService) SetDescriptor(ctx context.Context, dgst digest.Digest, desc distribution.Descriptor) error {
+	if err := dgst.Validate(); err != nil {
+		return err
+	}
+
+	if err := cache.ValidateDescriptor(desc); err != nil {
+		return err
+	}
+
+	conn := rbds.pool.Get()
+	defer conn.Close()
+
+	return rbds.setDescriptor(ctx, conn, dgst, desc)
+}
+
+func (rbds *redisBlobDescriptorService) setDescriptor(ctx context.Context, conn redis.Conn, dgst digest.Digest, desc distribution.Descriptor) error {
+	if _, err := conn.Do("HMSET", rbds.blobDescriptorHashKey(dgst),
+		"digest", desc.Digest,
+		"size", desc.Size); err != nil {
+		return err
+	}
+
+	// Only set mediatype if not already set.
+	if _, err := conn.Do("HSETNX", rbds.blobDescriptorHashKey(dgst),
+		"mediatype", desc.MediaType); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func (rbds *redisBlobDescriptorService) blobDescriptorHashKey(dgst digest.Digest) string {
+	return "blobs::" + dgst.String()
+}
+
+type repositoryScopedRedisBlobDescriptorService struct {
+	repo     string
+	upstream *redisBlobDescriptorService
+}
+
+var _ distribution.BlobDescriptorService = &repositoryScopedRedisBlobDescriptorService{}
+
+// Stat ensures that the digest is a member of the specified repository and
+// forwards the descriptor request to the global blob store. If the media type
+// differs for the repository, we override it.
+func (rsrbds *repositoryScopedRedisBlobDescriptorService) Stat(ctx context.Context, dgst digest.Digest) (distribution.Descriptor, error) {
+	if err := dgst.Validate(); err != nil {
+		return distribution.Descriptor{}, err
+	}
+
+	conn := rsrbds.upstream.pool.Get()
+	defer conn.Close()
+
+	// Check membership to repository first
+	member, err := redis.Bool(conn.Do("SISMEMBER", rsrbds.repositoryBlobSetKey(rsrbds.repo), dgst))
+	if err != nil {
+		return distribution.Descriptor{}, err
+	}
+
+	if !member {
+		return distribution.Descriptor{}, distribution.ErrBlobUnknown
+	}
+
+	upstream, err := rsrbds.upstream.stat(ctx, conn, dgst)
+	if err != nil {
+		return distribution.Descriptor{}, err
+	}
+
+	// We allow a per repository mediatype, let's look it up here.
+	mediatype, err := redis.String(conn.Do("HGET", rsrbds.blobDescriptorHashKey(dgst), "mediatype"))
+	if err != nil {
+		return distribution.Descriptor{}, err
+	}
+
+	if mediatype != "" {
+		upstream.MediaType = mediatype
+	}
+
+	return upstream, nil
+}
+
+// Clear removes the descriptor from the cache and forwards to the upstream descriptor store
+func (rsrbds *repositoryScopedRedisBlobDescriptorService) Clear(ctx context.Context, dgst digest.Digest) error {
+	if err := dgst.Validate(); err != nil {
+		return err
+	}
+
+	conn := rsrbds.upstream.pool.Get()
+	defer conn.Close()
+
+	// Check membership to repository first
+	member, err := redis.Bool(conn.Do("SISMEMBER", rsrbds.repositoryBlobSetKey(rsrbds.repo), dgst))
+	if err != nil {
+		return err
+	}
+
+	if !member {
+		return distribution.ErrBlobUnknown
+	}
+
+	return rsrbds.upstream.Clear(ctx, dgst)
+}
+
+func (rsrbds *repositoryScopedRedisBlobDescriptorService) SetDescriptor(ctx context.Context, dgst digest.Digest, desc distribution.Descriptor) error {
+	if err := dgst.Validate(); err != nil {
+		return err
+	}
+
+	if err := cache.ValidateDescriptor(desc); err != nil {
+		return err
+	}
+
+	if dgst != desc.Digest {
+		if dgst.Algorithm() == desc.Digest.Algorithm() {
+			return fmt.Errorf("redis cache: digest for descriptors differ but algorthim does not: %q != %q", dgst, desc.Digest)
+		}
+	}
+
+	conn := rsrbds.upstream.pool.Get()
+	defer conn.Close()
+
+	return rsrbds.setDescriptor(ctx, conn, dgst, desc)
+}
+
+func (rsrbds *repositoryScopedRedisBlobDescriptorService) setDescriptor(ctx context.Context, conn redis.Conn, dgst digest.Digest, desc distribution.Descriptor) error {
+	if _, err := conn.Do("SADD", rsrbds.repositoryBlobSetKey(rsrbds.repo), dgst); err != nil {
+		return err
+	}
+
+	if err := rsrbds.upstream.setDescriptor(ctx, conn, dgst, desc); err != nil {
+		return err
+	}
+
+	// Override repository mediatype.
+	if _, err := conn.Do("HSET", rsrbds.blobDescriptorHashKey(dgst), "mediatype", desc.MediaType); err != nil {
+		return err
+	}
+
+	// Also set the values for the primary descriptor, if they differ by
+	// algorithm (ie sha256 vs tarsum).
+	if desc.Digest != "" && dgst != desc.Digest && dgst.Algorithm() != desc.Digest.Algorithm() {
+		if err := rsrbds.setDescriptor(ctx, conn, desc.Digest, desc); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+func (rsrbds *repositoryScopedRedisBlobDescriptorService) blobDescriptorHashKey(dgst digest.Digest) string {
+	return "repository::" + rsrbds.repo + "::blobs::" + dgst.String()
+}
+
+func (rsrbds *repositoryScopedRedisBlobDescriptorService) repositoryBlobSetKey(repo string) string {
+	return "repository::" + rsrbds.repo + "::blobs"
+}

vendor/github.com/docker/distribution/registry/storage/cache/redis/redis_test.go

@@ -0,0 +1,51 @@
+package redis
+
+import (
+	"flag"
+	"os"
+	"testing"
+	"time"
+
+	"github.com/docker/distribution/registry/storage/cache"
+	"github.com/garyburd/redigo/redis"
+)
+
+var redisAddr string
+
+func init() {
+	flag.StringVar(&redisAddr, "test.registry.storage.cache.redis.addr", "", "configure the address of a test instance of redis")
+}
+
+// TestRedisLayerInfoCache exercises a live redis instance using the cache
+// implementation.
+func TestRedisBlobDescriptorCacheProvider(t *testing.T) {
+	if redisAddr == "" {
+		// fallback to an environement variable
+		redisAddr = os.Getenv("TEST_REGISTRY_STORAGE_CACHE_REDIS_ADDR")
+	}
+
+	if redisAddr == "" {
+		// skip if still not set
+		t.Skip("please set -registry.storage.cache.redis to test layer info cache against redis")
+	}
+
+	pool := &redis.Pool{
+		Dial: func() (redis.Conn, error) {
+			return redis.Dial("tcp", redisAddr)
+		},
+		MaxIdle:   1,
+		MaxActive: 2,
+		TestOnBorrow: func(c redis.Conn, t time.Time) error {
+			_, err := c.Do("PING")
+			return err
+		},
+		Wait: false, // if a connection is not avialable, proceed without cache.
+	}
+
+	// Clear the database
+	if _, err := pool.Get().Do("FLUSHDB"); err != nil {
+		t.Fatalf("unexpected error flushing redis db: %v", err)
+	}
+
+	cache.CheckBlobDescriptorCache(t, NewRedisBlobDescriptorCacheProvider(pool))
+}

vendor/github.com/docker/distribution/registry/storage/cache/suite.go

@@ -0,0 +1,178 @@
+package cache
+
+import (
+	"testing"
+
+	"github.com/docker/distribution"
+	"github.com/docker/distribution/context"
+	"github.com/docker/distribution/digest"
+)
+
+// CheckBlobDescriptorCache takes a cache implementation through a common set
+// of operations. If adding new tests, please add them here so new
+// implementations get the benefit. This should be used for unit tests.
+func CheckBlobDescriptorCache(t *testing.T, provider BlobDescriptorCacheProvider) {
+	ctx := context.Background()
+
+	checkBlobDescriptorCacheEmptyRepository(t, ctx, provider)
+	checkBlobDescriptorCacheSetAndRead(t, ctx, provider)
+}
+
+func checkBlobDescriptorCacheEmptyRepository(t *testing.T, ctx context.Context, provider BlobDescriptorCacheProvider) {
+	if _, err := provider.Stat(ctx, "sha384:abc"); err != distribution.ErrBlobUnknown {
+		t.Fatalf("expected unknown blob error with empty store: %v", err)
+	}
+
+	cache, err := provider.RepositoryScoped("")
+	if err == nil {
+		t.Fatalf("expected an error when asking for invalid repo")
+	}
+
+	cache, err = provider.RepositoryScoped("foo/bar")
+	if err != nil {
+		t.Fatalf("unexpected error getting repository: %v", err)
+	}
+
+	if err := cache.SetDescriptor(ctx, "", distribution.Descriptor{
+		Digest:    "sha384:abc",
+		Size:      10,
+		MediaType: "application/octet-stream"}); err != digest.ErrDigestInvalidFormat {
+		t.Fatalf("expected error with invalid digest: %v", err)
+	}
+
+	if err := cache.SetDescriptor(ctx, "sha384:abc", distribution.Descriptor{
+		Digest:    "",
+		Size:      10,
+		MediaType: "application/octet-stream"}); err == nil {
+		t.Fatalf("expected error setting value on invalid descriptor")
+	}
+
+	if _, err := cache.Stat(ctx, ""); err != digest.ErrDigestInvalidFormat {
+		t.Fatalf("expected error checking for cache item with empty digest: %v", err)
+	}
+
+	if _, err := cache.Stat(ctx, "sha384:abc"); err != distribution.ErrBlobUnknown {
+		t.Fatalf("expected unknown blob error with empty repo: %v", err)
+	}
+}
+
+func checkBlobDescriptorCacheSetAndRead(t *testing.T, ctx context.Context, provider BlobDescriptorCacheProvider) {
+	localDigest := digest.Digest("sha384:abc")
+	expected := distribution.Descriptor{
+		Digest:    "sha256:abc",
+		Size:      10,
+		MediaType: "application/octet-stream"}
+
+	cache, err := provider.RepositoryScoped("foo/bar")
+	if err != nil {
+		t.Fatalf("unexpected error getting scoped cache: %v", err)
+	}
+
+	if err := cache.SetDescriptor(ctx, localDigest, expected); err != nil {
+		t.Fatalf("error setting descriptor: %v", err)
+	}
+
+	desc, err := cache.Stat(ctx, localDigest)
+	if err != nil {
+		t.Fatalf("unexpected error statting fake2:abc: %v", err)
+	}
+
+	if expected != desc {
+		t.Fatalf("unexpected descriptor: %#v != %#v", expected, desc)
+	}
+
+	// also check that we set the canonical key ("fake:abc")
+	desc, err = cache.Stat(ctx, localDigest)
+	if err != nil {
+		t.Fatalf("descriptor not returned for canonical key: %v", err)
+	}
+
+	if expected != desc {
+		t.Fatalf("unexpected descriptor: %#v != %#v", expected, desc)
+	}
+
+	// ensure that global gets extra descriptor mapping
+	desc, err = provider.Stat(ctx, localDigest)
+	if err != nil {
+		t.Fatalf("expected blob unknown in global cache: %v, %v", err, desc)
+	}
+
+	if desc != expected {
+		t.Fatalf("unexpected descriptor: %#v != %#v", expected, desc)
+	}
+
+	// get at it through canonical descriptor
+	desc, err = provider.Stat(ctx, expected.Digest)
+	if err != nil {
+		t.Fatalf("unexpected error checking glboal descriptor: %v", err)
+	}
+
+	if desc != expected {
+		t.Fatalf("unexpected descriptor: %#v != %#v", expected, desc)
+	}
+
+	// now, we set the repo local mediatype to something else and ensure it
+	// doesn't get changed in the provider cache.
+	expected.MediaType = "application/json"
+
+	if err := cache.SetDescriptor(ctx, localDigest, expected); err != nil {
+		t.Fatalf("unexpected error setting descriptor: %v", err)
+	}
+
+	desc, err = cache.Stat(ctx, localDigest)
+	if err != nil {
+		t.Fatalf("unexpected error getting descriptor: %v", err)
+	}
+
+	if desc != expected {
+		t.Fatalf("unexpected descriptor: %#v != %#v", desc, expected)
+	}
+
+	desc, err = provider.Stat(ctx, localDigest)
+	if err != nil {
+		t.Fatalf("unexpected error getting global descriptor: %v", err)
+	}
+
+	expected.MediaType = "application/octet-stream" // expect original mediatype in global
+
+	if desc != expected {
+		t.Fatalf("unexpected descriptor: %#v != %#v", desc, expected)
+	}
+}
+
+func checkBlobDescriptorClear(t *testing.T, ctx context.Context, provider BlobDescriptorCacheProvider) {
+	localDigest := digest.Digest("sha384:abc")
+	expected := distribution.Descriptor{
+		Digest:    "sha256:abc",
+		Size:      10,
+		MediaType: "application/octet-stream"}
+
+	cache, err := provider.RepositoryScoped("foo/bar")
+	if err != nil {
+		t.Fatalf("unexpected error getting scoped cache: %v", err)
+	}
+
+	if err := cache.SetDescriptor(ctx, localDigest, expected); err != nil {
+		t.Fatalf("error setting descriptor: %v", err)
+	}
+
+	desc, err := cache.Stat(ctx, localDigest)
+	if err != nil {
+		t.Fatalf("unexpected error statting fake2:abc: %v", err)
+	}
+
+	if expected != desc {
+		t.Fatalf("unexpected descriptor: %#v != %#v", expected, desc)
+	}
+
+	err = cache.Clear(ctx, localDigest)
+	if err != nil {
+		t.Fatalf("unexpected error deleting descriptor")
+	}
+
+	nonExistantDigest := digest.Digest("sha256:aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa")
+	err = cache.Clear(ctx, nonExistantDigest)
+	if err == nil {
+		t.Fatalf("expected error deleting unknown descriptor")
+	}
+}