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

configuration/configuration.go

@@ -242,6 +242,8 @@ func (storage Storage) Type() string {
 			// allow configuration of caching
 		case "delete":
 			// allow configuration of delete
+		case "redirect":
+			// allow configuration of redirect
 		default:
 			return k
 		}
@@ -275,7 +277,8 @@ func (storage *Storage) UnmarshalYAML(unmarshal func(interface{}) error) error {
 					// allow configuration of caching
 				case "delete":
 					// allow configuration of delete
-
+				case "redirect":
+					// allow configuration of redirect
 				default:
 					types = append(types, k)
 				}

docs/configuration.md

@@ -104,6 +104,8 @@ information about each option that appears later in this page.
         region: fr
         container: containername
         rootdirectory: /swift/object/name/prefix
+      redirect:
+        disable: false
       cache:
         blobdescriptor: redis
       maintenance:
@@ -328,6 +330,8 @@ Permitted values are `error`, `warn`, `info` and `debug`. The default is
           age: 168h
           interval: 24h
           dryrun: false
+      redirect:
+        disable: false
 
 The storage option is **required** and defines which storage backend is in use.
 You must configure one backend; if you configure more, the registry returns an error.
@@ -350,6 +354,21 @@ map.
 >are equivalent, `layerinfo` has been deprecated, in favor or
 >`blobdescriptor`.
 
+### redirect
+
+The `redirect` subsection provides configuration for managing redirects from
+content backends. For backends that support it, redirecting is enabled by
+default. Certain deployment scenarios may prefer to route all data through the
+Registry, rather than redirecting to the backend. This may be more efficient
+when using a backend that is not colocated or when a registry instance is
+doing aggressive caching.
+
+Redirects can be disabled by adding a single flag `disable`, set to `true`
+under the `redirect` section:
+
+  redirect:
+    disable: true
+
 ### filesystem
 
 The `filesystem` storage backend uses the local disk to store registry files. It

notifications/listener_test.go

@@ -18,7 +18,7 @@ import (
 
 func TestListener(t *testing.T) {
 	ctx := context.Background()
-	registry := storage.NewRegistryWithDriver(ctx, inmemory.New(), memory.NewInMemoryBlobDescriptorCacheProvider(), true)
+	registry := storage.NewRegistryWithDriver(ctx, inmemory.New(), memory.NewInMemoryBlobDescriptorCacheProvider(), true, true)
 	tl := &testListener{
 		ops: make(map[string]int),
 	}

registry/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"])

registry/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()

registry/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)

registry/storage/blobserver.go

@@ -20,6 +20,7 @@ type blobServer struct {
 	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:
+		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)

registry/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{

registry/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)

registry/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,
@@ -45,6 +48,7 @@ func NewRegistryWithDriver(ctx context.Context, driver storagedriver.StorageDriv
 			driver:   driver,
 			statter:  statter,
 			pathFn:   bs.path,
+			redirect: redirect,
 		},
 		blobDescriptorCacheProvider: blobDescriptorCacheProvider,
 		deleteEnabled:               deleteEnabled,