Allow disabling of starage driver redirects

Storage drivers can implement a method called URLFor which can return a direct
url for a given path. The functionality allows the registry to direct clients
to download content directly from the backend storage. This is commonly used
with s3 and cloudfront. Under certain conditions, such as when the registry is
not local to the backend, these redirects can hurt performance and waste
incoming bandwidth on pulls. This feature addition allows one to disable this
feature, if required.

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

Conflicts:
	configuration/configuration.go
	registry/handlers/app.go
	registry/storage/catalog_test.go
	registry/storage/manifeststore_test.go
	registry/storage/registry.go

docs/handlers/app.go

@@ -106,7 +106,8 @@ func NewApp(ctx context.Context, configuration configuration.Configuration) *App
 	app.configureRedis(&configuration)
 	app.configureLogHook(&configuration)
 
-	deleteEnabled := false
+	// configure deletion
+	var deleteEnabled bool
 	if d, ok := configuration.Storage["delete"]; ok {
 		e, ok := d["enabled"]
 		if ok {
@@ -116,6 +117,22 @@ func NewApp(ctx context.Context, configuration configuration.Configuration) *App
 		}
 	}
 
+	// configure redirects
+	var redirectDisabled bool
+	if redirectConfig, ok := configuration.Storage["redirect"]; ok {
+		v := redirectConfig["disable"]
+		switch v := v.(type) {
+		case bool:
+			redirectDisabled = v
+		default:
+			panic(fmt.Sprintf("invalid type for redirect config: %#v", redirectConfig))
+		}
+
+		if redirectDisabled {
+			ctxu.GetLogger(app).Infof("backend redirection disabled")
+		}
+	}
+
 	// configure storage caches
 	if cc, ok := configuration.Storage["cache"]; ok {
 		v, ok := cc["blobdescriptor"]
@@ -129,10 +146,10 @@ func NewApp(ctx context.Context, configuration configuration.Configuration) *App
 			if app.redis == nil {
 				panic("redis configuration required to use for layerinfo cache")
 			}
-			app.registry = storage.NewRegistryWithDriver(app, app.driver, rediscache.NewRedisBlobDescriptorCacheProvider(app.redis), deleteEnabled)
+			app.registry = storage.NewRegistryWithDriver(app, app.driver, rediscache.NewRedisBlobDescriptorCacheProvider(app.redis), deleteEnabled, !redirectDisabled)
 			ctxu.GetLogger(app).Infof("using redis blob descriptor cache")
 		case "inmemory":
-			app.registry = storage.NewRegistryWithDriver(app, app.driver, memorycache.NewInMemoryBlobDescriptorCacheProvider(), deleteEnabled)
+			app.registry = storage.NewRegistryWithDriver(app, app.driver, memorycache.NewInMemoryBlobDescriptorCacheProvider(), deleteEnabled, !redirectDisabled)
 			ctxu.GetLogger(app).Infof("using inmemory blob descriptor cache")
 		default:
 			if v != "" {
@@ -143,7 +160,7 @@ func NewApp(ctx context.Context, configuration configuration.Configuration) *App
 
 	if app.registry == nil {
 		// configure the registry if no cache section is available.
-		app.registry = storage.NewRegistryWithDriver(app.Context, app.driver, nil, deleteEnabled)
+		app.registry = storage.NewRegistryWithDriver(app.Context, app.driver, nil, deleteEnabled, !redirectDisabled)
 	}
 
 	app.registry, err = applyRegistryMiddleware(app.registry, configuration.Middleware["registry"])

docs/handlers/app_test.go

@@ -31,7 +31,7 @@ func TestAppDispatcher(t *testing.T) {
 		Context:  ctx,
 		router:   v2.Router(),
 		driver:   driver,
-		registry: storage.NewRegistryWithDriver(ctx, driver, memorycache.NewInMemoryBlobDescriptorCacheProvider(), true),
+		registry: storage.NewRegistryWithDriver(ctx, driver, memorycache.NewInMemoryBlobDescriptorCacheProvider(), true, true),
 	}
 	server := httptest.NewServer(app)
 	router := v2.Router()

docs/storage/blob_test.go

@@ -33,7 +33,7 @@ func TestSimpleBlobUpload(t *testing.T) {
 	ctx := context.Background()
 	imageName := "foo/bar"
 	driver := inmemory.New()
-	registry := NewRegistryWithDriver(ctx, driver, memory.NewInMemoryBlobDescriptorCacheProvider(), true)
+	registry := NewRegistryWithDriver(ctx, driver, memory.NewInMemoryBlobDescriptorCacheProvider(), true, true)
 	repository, err := registry.Repository(ctx, imageName)
 	if err != nil {
 		t.Fatalf("unexpected error getting repo: %v", err)
@@ -193,7 +193,7 @@ func TestSimpleBlobUpload(t *testing.T) {
 	}
 
 	// Reuse state to test delete with a delete-disabled registry
-	registry = NewRegistryWithDriver(ctx, driver, memory.NewInMemoryBlobDescriptorCacheProvider(), false)
+	registry = NewRegistryWithDriver(ctx, driver, memory.NewInMemoryBlobDescriptorCacheProvider(), false, true)
 	repository, err = registry.Repository(ctx, imageName)
 	if err != nil {
 		t.Fatalf("unexpected error getting repo: %v", err)
@@ -212,7 +212,7 @@ func TestSimpleBlobRead(t *testing.T) {
 	ctx := context.Background()
 	imageName := "foo/bar"
 	driver := inmemory.New()
-	registry := NewRegistryWithDriver(ctx, driver, memory.NewInMemoryBlobDescriptorCacheProvider(), true)
+	registry := NewRegistryWithDriver(ctx, driver, memory.NewInMemoryBlobDescriptorCacheProvider(), true, true)
 	repository, err := registry.Repository(ctx, imageName)
 	if err != nil {
 		t.Fatalf("unexpected error getting repo: %v", err)
@@ -316,7 +316,7 @@ func TestLayerUploadZeroLength(t *testing.T) {
 	ctx := context.Background()
 	imageName := "foo/bar"
 	driver := inmemory.New()
-	registry := NewRegistryWithDriver(ctx, driver, memory.NewInMemoryBlobDescriptorCacheProvider(), true)
+	registry := NewRegistryWithDriver(ctx, driver, memory.NewInMemoryBlobDescriptorCacheProvider(), true, true)
 	repository, err := registry.Repository(ctx, imageName)
 	if err != nil {
 		t.Fatalf("unexpected error getting repo: %v", err)

docs/storage/blobserver.go

@@ -17,9 +17,10 @@ const blobCacheControlMaxAge = 365 * 24 * time.Hour
 // blobServer simply serves blobs from a driver instance using a path function
 // to identify paths and a descriptor service to fill in metadata.
 type blobServer struct {
-	driver  driver.StorageDriver
+	driver   driver.StorageDriver
-	statter distribution.BlobStatter
+	statter  distribution.BlobStatter
-	pathFn  func(dgst digest.Digest) (string, error)
+	pathFn   func(dgst digest.Digest) (string, error)
+	redirect bool // allows disabling URLFor redirects
 }
 
 func (bs *blobServer) ServeBlob(ctx context.Context, w http.ResponseWriter, r *http.Request, dgst digest.Digest) error {
@@ -37,8 +38,13 @@ func (bs *blobServer) ServeBlob(ctx context.Context, w http.ResponseWriter, r *h
 
 	switch err {
 	case nil:
-		// Redirect to storage URL.
+		if bs.redirect {
-		http.Redirect(w, r, redirectURL, http.StatusTemporaryRedirect)
+			// Redirect to storage URL.
+			http.Redirect(w, r, redirectURL, http.StatusTemporaryRedirect)
+			return err
+		}
+
+		fallthrough
 	case driver.ErrUnsupportedMethod:
 		// Fallback to serving the content directly.
 		br, err := newFileReader(ctx, bs.driver, path, desc.Size)

docs/storage/catalog_test.go

@@ -22,7 +22,7 @@ func setupFS(t *testing.T) *setupEnv {
 	d := inmemory.New()
 	c := []byte("")
 	ctx := context.Background()
-	registry := NewRegistryWithDriver(ctx, d, memory.NewInMemoryBlobDescriptorCacheProvider(), false)
+	registry := NewRegistryWithDriver(ctx, d, memory.NewInMemoryBlobDescriptorCacheProvider(), false, true)
 	rootpath, _ := defaultPathMapper.path(repositoriesRootPathSpec{})
 
 	repos := []string{

docs/storage/manifeststore_test.go

@@ -29,7 +29,8 @@ type manifestStoreTestEnv struct {
 func newManifestStoreTestEnv(t *testing.T, name, tag string) *manifestStoreTestEnv {
 	ctx := context.Background()
 	driver := inmemory.New()
-	registry := NewRegistryWithDriver(ctx, driver, memory.NewInMemoryBlobDescriptorCacheProvider(), true)
+	registry := NewRegistryWithDriver(ctx, driver, memory.NewInMemoryBlobDescriptorCacheProvider(), true, true)
+
 	repo, err := registry.Repository(ctx, name)
 	if err != nil {
 		t.Fatalf("unexpected error getting repo: %v", err)
@@ -347,7 +348,7 @@ func TestManifestStorage(t *testing.T) {
 		t.Errorf("Deleted manifest get returned non-nil")
 	}
 
-	r := NewRegistryWithDriver(ctx, env.driver, memory.NewInMemoryBlobDescriptorCacheProvider(), false)
+	r := NewRegistryWithDriver(ctx, env.driver, memory.NewInMemoryBlobDescriptorCacheProvider(), false, true)
 	repo, err := r.Repository(ctx, env.name)
 	if err != nil {
 		t.Fatalf("unexpected error getting repo: %v", err)

docs/storage/registry.go

@@ -20,9 +20,12 @@ type registry struct {
 
 // NewRegistryWithDriver creates a new registry instance from the provided
 // driver. The resulting registry may be shared by multiple goroutines but is
-// cheap to allocate.
+// cheap to allocate. If redirect is true, the backend blob server will
-func NewRegistryWithDriver(ctx context.Context, driver storagedriver.StorageDriver, blobDescriptorCacheProvider cache.BlobDescriptorCacheProvider, deleteEnabled bool) distribution.Namespace {
+// attempt to use (StorageDriver).URLFor to serve all blobs.
-
+//
+// TODO(stevvooe): This function signature is getting out of hand. Move to
+// functional options for instance configuration.
+func NewRegistryWithDriver(ctx context.Context, driver storagedriver.StorageDriver, blobDescriptorCacheProvider cache.BlobDescriptorCacheProvider, deleteEnabled bool, redirect bool) distribution.Namespace {
 	// create global statter, with cache.
 	var statter distribution.BlobDescriptorService = &blobStatter{
 		driver: driver,
@@ -42,9 +45,10 @@ func NewRegistryWithDriver(ctx context.Context, driver storagedriver.StorageDriv
 	return &registry{
 		blobStore: bs,
 		blobServer: &blobServer{
-			driver:  driver,
+			driver:   driver,
-			statter: statter,
+			statter:  statter,
-			pathFn:  bs.path,
+			pathFn:   bs.path,
+			redirect: redirect,
 		},
 		blobDescriptorCacheProvider: blobDescriptorCacheProvider,
 		deleteEnabled:               deleteEnabled,