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/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
-	statter distribution.BlobStatter
-	pathFn  func(dgst digest.Digest) (string, error)
+	driver   driver.StorageDriver
+	statter  distribution.BlobStatter
+	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.
-		http.Redirect(w, r, redirectURL, http.StatusTemporaryRedirect)
+		if bs.redirect {
+			// 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.
-func NewRegistryWithDriver(ctx context.Context, driver storagedriver.StorageDriver, blobDescriptorCacheProvider cache.BlobDescriptorCacheProvider, deleteEnabled bool) distribution.Namespace {
-
+// cheap to allocate. If redirect is true, the backend blob server will
+// 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,
-			statter: statter,
-			pathFn:  bs.path,
+			driver:   driver,
+			statter:  statter,
+			pathFn:   bs.path,
+			redirect: redirect,
 		},
 		blobDescriptorCacheProvider: blobDescriptorCacheProvider,
 		deleteEnabled:               deleteEnabled,