registry: implement blob deletion

pkg/registry/blobs.go

@@ -76,6 +76,13 @@ type blobPutHandler interface {
 	Put(ctx context.Context, repo string, h v1.Hash, rc io.ReadCloser) error
 }
 
+// blobDeleteHandler is an extension interface representing a blob storage
+// backend that can delete blob contents.
+type blobDeleteHandler interface {
+	// Delete the blob contents.
+	Delete(ctx context.Context, repo string, h v1.Hash) error
+}
+
 // redirectError represents a signal that the blob handler doesn't have the blob
 // contents, but that those contents are at another location which registry
 // clients should redirect to.
@@ -129,6 +136,17 @@ func (m *memHandler) Put(_ context.Context, _ string, h v1.Hash, rc io.ReadClose
 	m.m[h.String()] = all
 	return nil
 }
+func (m *memHandler) Delete(_ context.Context, _ string, h v1.Hash) error {
+	m.lock.Lock()
+	defer m.lock.Unlock()
+
+	if _, found := m.m[h.String()]; !found {
+		return errNotFound
+	}
+
+	delete(m.m, h.String())
+	return nil
+}
 
 // blobs
 type blobs struct {
@@ -435,6 +453,26 @@ func (b *blobs) handle(resp http.ResponseWriter, req *http.Request) *regError {
 		resp.WriteHeader(http.StatusCreated)
 		return nil
 
+	case http.MethodDelete:
+		bdh, ok := b.blobHandler.(blobDeleteHandler)
+		if !ok {
+			return regErrUnsupported
+		}
+
+		h, err := v1.NewHash(target)
+		if err != nil {
+			return &regError{
+				Status:  http.StatusBadRequest,
+				Code:    "NAME_INVALID",
+				Message: "invalid digest",
+			}
+		}
+		if err := bdh.Delete(req.Context(), repo, h); err != nil {
+			return regErrInternal(err)
+		}
+		resp.WriteHeader(http.StatusAccepted)
+		return nil
+
 	default:
 		return &regError{
 			Status:  http.StatusBadRequest,

pkg/registry/registry_test.go

@@ -149,6 +149,13 @@ func TestCalls(t *testing.T) {
 				"Docker-Content-Digest": "sha256:2c26b46b68ffc68ff99b453c1d30413413422d706483bfa0f98a5e886266e7ae",
 			},
 		},
+		{
+			Description: "DELETE blob",
+			Digests:     map[string]string{"sha256:2c26b46b68ffc68ff99b453c1d30413413422d706483bfa0f98a5e886266e7ae": "foo"},
+			Method:      "DELETE",
+			URL:         "/v2/foo/blobs/sha256:2c26b46b68ffc68ff99b453c1d30413413422d706483bfa0f98a5e886266e7ae",
+			Code:        http.StatusAccepted,
+		},
 		{
 			Description: "blob url with no container",
 			Method:      "GET",