Add glide.yaml and vendor deps

vendor/github.com/docker/distribution/registry/middleware/repository/middleware.go

@@ -0,0 +1,40 @@
+package middleware
+
+import (
+	"fmt"
+
+	"github.com/docker/distribution"
+	"github.com/docker/distribution/context"
+)
+
+// InitFunc is the type of a RepositoryMiddleware factory function and is
+// used to register the constructor for different RepositoryMiddleware backends.
+type InitFunc func(ctx context.Context, 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(ctx context.Context, name string, options map[string]interface{}, repository distribution.Repository) (distribution.Repository, error) {
+	if middlewares != nil {
+		if initFunc, exists := middlewares[name]; exists {
+			return initFunc(ctx, repository, options)
+		}
+	}
+
+	return nil, fmt.Errorf("no repository middleware registered with name: %s", name)
+}