Middleware!

Convert middleware in the config to be a map of type->[]Middleware

Add support for registry & repository middleware.

Some naming updates as well.

Signed-off-by: Andy Goldstein <agoldste@redhat.com>

docs/handlers/app.go

@@ -13,6 +13,8 @@ import (
 	"github.com/docker/distribution/notifications"
 	"github.com/docker/distribution/registry/api/v2"
 	"github.com/docker/distribution/registry/auth"
+	registrymiddleware "github.com/docker/distribution/registry/middleware/registry"
+	repositorymiddleware "github.com/docker/distribution/registry/middleware/repository"
 	"github.com/docker/distribution/registry/storage"
 	storagedriver "github.com/docker/distribution/registry/storage/driver"
 	"github.com/docker/distribution/registry/storage/driver/factory"
@@ -89,7 +91,16 @@ func NewApp(ctx context.Context, configuration configuration.Configuration) *App
 	}
 
 	app.configureEvents(&configuration)
+
 	app.registry = storage.NewRegistryWithDriver(app.driver)
+	for _, mw := range configuration.Middleware["registry"] {
+		rmw, err := registrymiddleware.Get(mw.Name, mw.Options, app.registry)
+		if err != nil {
+			panic(fmt.Sprintf("unable to configure registry middleware (%s): %s", mw.Name, err))
+		}
+		app.registry = rmw
+	}
+
 	authType := configuration.Auth.Type()
 
 	if authType != "" {
@@ -100,23 +111,13 @@ func NewApp(ctx context.Context, configuration configuration.Configuration) *App
 		app.accessController = accessController
 	}
 
-	for _, mw := range configuration.Middleware {
+	for _, mw := range configuration.Middleware["storage"] {
-		if mw.Inject == "registry" {
+		smw, err := storagemiddleware.Get(mw.Name, mw.Options, app.driver)
-			// registry middleware can director wrap app.registry identically to storage middlewares with driver
-			panic(fmt.Sprintf("unable to configure registry middleware (%s): %v", mw.Name, err))
-		} else if mw.Inject == "repository" {
-			// we have to do something more intelligent with repository middleware, It needs to be staged
-			// for later to be wrapped around the repository at request time.
-			panic(fmt.Sprintf("unable to configure repository middleware (%s): %v", mw.Name, err))
-		} else if mw.Inject == "storage" {
-			smw, err := storagemiddleware.GetStorageMiddleware(mw.Name, mw.Options, app.driver)
-
 		if err != nil {
 			panic(fmt.Sprintf("unable to configure storage middleware (%s): %v", mw.Name, err))
 		}
 		app.driver = smw
 	}
-	}
 
 	return app
 }
@@ -256,6 +257,14 @@ func (app *App) dispatcher(dispatch dispatchFunc) http.Handler {
 			context.Repository = notifications.Listen(
 				repository,
 				app.eventBridge(context, r))
+
+			for _, mw := range app.Config.Middleware["repository"] {
+				rmw, err := repositorymiddleware.Get(mw.Name, mw.Options, context.Repository)
+				if err != nil {
+					panic(fmt.Sprintf("unable to configure repository middleware (%s): %s", mw.Name, err))
+				}
+				context.Repository = rmw
+			}
 		}
 
 		handler := dispatch(context, r)

docs/middleware/registry/middleware.go

@@ -0,0 +1,39 @@
+package middleware
+
+import (
+	"fmt"
+
+	"github.com/docker/distribution"
+)
+
+// InitFunc is the type of a RegistryMiddleware factory function and is
+// used to register the contsructor for different RegistryMiddleware backends.
+type InitFunc func(registry distribution.Registry, options map[string]interface{}) (distribution.Registry, error)
+
+var middlewares map[string]InitFunc
+
+// Register is used to register an InitFunc for
+// a RegistryMiddleware backend with the given name.
+func Register(name string, initFunc InitFunc) error {
+	if middlewares == nil {
+		middlewares = make(map[string]InitFunc)
+	}
+	if _, exists := middlewares[name]; exists {
+		return fmt.Errorf("name already registered: %s", name)
+	}
+
+	middlewares[name] = initFunc
+
+	return nil
+}
+
+// Get constructs a RegistryMiddleware with the given options using the named backend.
+func Get(name string, options map[string]interface{}, registry distribution.Registry) (distribution.Registry, error) {
+	if middlewares != nil {
+		if initFunc, exists := middlewares[name]; exists {
+			return initFunc(registry, options)
+		}
+	}
+
+	return nil, fmt.Errorf("no registry middleware registered with name: %s", name)
+}

docs/middleware/repository/middleware.go

@@ -0,0 +1,39 @@
+package middleware
+
+import (
+	"fmt"
+
+	"github.com/docker/distribution"
+)
+
+// InitFunc is the type of a RepositoryMiddleware factory function and is
+// used to register the contsructor for different RepositoryMiddleware backends.
+type InitFunc func(repository distribution.Repository, options map[string]interface{}) (distribution.Repository, error)
+
+var middlewares map[string]InitFunc
+
+// Register is used to register an InitFunc for
+// a RepositoryMiddleware backend with the given name.
+func Register(name string, initFunc InitFunc) error {
+	if middlewares == nil {
+		middlewares = make(map[string]InitFunc)
+	}
+	if _, exists := middlewares[name]; exists {
+		return fmt.Errorf("name already registered: %s", name)
+	}
+
+	middlewares[name] = initFunc
+
+	return nil
+}
+
+// Get constructs a RepositoryMiddleware with the given options using the named backend.
+func Get(name string, options map[string]interface{}, repository distribution.Repository) (distribution.Repository, error) {
+	if middlewares != nil {
+		if initFunc, exists := middlewares[name]; exists {
+			return initFunc(repository, options)
+		}
+	}
+
+	return nil, fmt.Errorf("no repository middleware registered with name: %s", name)
+}

docs/storage/driver/middleware/cloudfront/middleware.go

@@ -115,5 +115,5 @@ func (lh *cloudFrontStorageMiddleware) URLFor(path string, options map[string]in
 
 // init registers the cloudfront layerHandler backend.
 func init() {
-	storagemiddleware.RegisterStorageMiddleware("cloudfront", storagemiddleware.InitFunc(newCloudFrontStorageMiddleware))
+	storagemiddleware.Register("cloudfront", storagemiddleware.InitFunc(newCloudFrontStorageMiddleware))
 }

docs/storage/driver/middleware/storagemiddleware.go

@@ -12,9 +12,9 @@ type InitFunc func(storageDriver storagedriver.StorageDriver, options map[string
 
 var storageMiddlewares map[string]InitFunc
 
-// RegisterStorageMiddleware is used to register an StorageMiddlewareInitFunc for
+// Register is used to register an InitFunc for
 // a StorageMiddleware backend with the given name.
-func RegisterStorageMiddleware(name string, initFunc InitFunc) error {
+func Register(name string, initFunc InitFunc) error {
 	if storageMiddlewares == nil {
 		storageMiddlewares = make(map[string]InitFunc)
 	}
@@ -27,9 +27,8 @@ func RegisterStorageMiddleware(name string, initFunc InitFunc) error {
 	return nil
 }
 
-// GetStorageMiddleware constructs a StorageMiddleware
+// Get constructs a StorageMiddleware with the given options using the named backend.
-// with the given options using the named backend.
+func Get(name string, options map[string]interface{}, storageDriver storagedriver.StorageDriver) (storagedriver.StorageDriver, error) {
-func GetStorageMiddleware(name string, options map[string]interface{}, storageDriver storagedriver.StorageDriver) (storagedriver.StorageDriver, error) {
 	if storageMiddlewares != nil {
 		if initFunc, exists := storageMiddlewares[name]; exists {
 			return initFunc(storageDriver, options)