Implement cross-registry blob mounting experiment (#1388)

This is currently only implemented by Google but we'd like to upstream
this to the distribution spec. There's a small possibility that this
will break registries that don't implement the spec properly.

We signal the domain of the origin registry with the "origin"
querystring parameter.

pkg/v1/remote/check.go

@@ -39,7 +39,7 @@ func CheckPushPermission(ref name.Reference, kc authn.Keychain, t http.RoundTrip
 		client:  &http.Client{Transport: tr},
 		context: context.Background(),
 	}
-	loc, _, err := w.initiateUpload("", "")
+	loc, _, err := w.initiateUpload("", "", "")
 	if loc != "" {
 		// Since we're only initiating the upload to check whether we
 		// can, we should attempt to cancel it, in case initiating

pkg/v1/remote/write.go

@@ -267,13 +267,16 @@ func (w *writer) checkExistingManifest(h v1.Hash, mt types.MediaType) (bool, err
 // On success, the layer was either mounted (nothing more to do) or a blob
 // upload was initiated and the body of that blob should be sent to the returned
 // location.
-func (w *writer) initiateUpload(from, mount string) (location string, mounted bool, err error) {
+func (w *writer) initiateUpload(from, mount, origin string) (location string, mounted bool, err error) {
 	u := w.url(fmt.Sprintf("/v2/%s/blobs/uploads/", w.repo.RepositoryStr()))
 	uv := url.Values{}
 	if mount != "" && from != "" {
 		// Quay will fail if we specify a "mount" without a "from".
-		uv["mount"] = []string{mount}
-		uv["from"] = []string{from}
+		uv.Set("mount", mount)
+		uv.Set("from", from)
+		if origin != "" {
+			uv.Set("origin", origin)
+		}
 	}
 	u.RawQuery = uv.Encode()
 
@@ -411,7 +414,7 @@ func (w *writer) incrProgress(written int64) {
 // uploadOne performs a complete upload of a single layer.
 func (w *writer) uploadOne(ctx context.Context, l v1.Layer) error {
 	tryUpload := func() error {
-		var from, mount string
+		var from, mount, origin string
 		if h, err := l.Digest(); err == nil {
 			// If we know the digest, this isn't a streaming layer. Do an existence
 			// check so we can skip uploading the layer if possible.
@@ -432,12 +435,11 @@ func (w *writer) uploadOne(ctx context.Context, l v1.Layer) error {
 			mount = h.String()
 		}
 		if ml, ok := l.(*MountableLayer); ok {
-			if w.repo.RegistryStr() == ml.Reference.Context().RegistryStr() {
-				from = ml.Reference.Context().RepositoryStr()
-			}
+			from = ml.Reference.Context().RepositoryStr()
+			origin = ml.Reference.Context().RegistryStr()
 		}
 
-		location, mounted, err := w.initiateUpload(from, mount)
+		location, mounted, err := w.initiateUpload(from, mount, origin)
 		if err != nil {
 			return err
 		} else if mounted {

pkg/v1/remote/write_test.go

@@ -257,7 +257,7 @@ func TestInitiateUploadNoMountsExists(t *testing.T) {
 	}
 	defer closer.Close()
 
-	_, mounted, err := w.initiateUpload("baz/bar", h.String())
+	_, mounted, err := w.initiateUpload("baz/bar", h.String(), "")
 	if err != nil {
 		t.Errorf("intiateUpload() = %v", err)
 	}
@@ -295,7 +295,7 @@ func TestInitiateUploadNoMountsInitiated(t *testing.T) {
 	}
 	defer closer.Close()
 
-	location, mounted, err := w.initiateUpload("baz/bar", h.String())
+	location, mounted, err := w.initiateUpload("baz/bar", h.String(), "")
 	if err != nil {
 		t.Errorf("intiateUpload() = %v", err)
 	}
@@ -334,7 +334,7 @@ func TestInitiateUploadNoMountsBadStatus(t *testing.T) {
 	}
 	defer closer.Close()
 
-	location, mounted, err := w.initiateUpload("baz/bar", h.String())
+	location, mounted, err := w.initiateUpload("baz/bar", h.String(), "")
 	if err == nil {
 		t.Errorf("intiateUpload() = %v, %v; wanted error", location, mounted)
 	}
@@ -367,7 +367,7 @@ func TestInitiateUploadMountsWithMountFromDifferentRegistry(t *testing.T) {
 	}
 	defer closer.Close()
 
-	_, mounted, err := w.initiateUpload("baz/bar", h.String())
+	_, mounted, err := w.initiateUpload("baz/bar", h.String(), "")
 	if err != nil {
 		t.Errorf("intiateUpload() = %v", err)
 	}
@@ -407,7 +407,49 @@ func TestInitiateUploadMountsWithMountFromTheSameRegistry(t *testing.T) {
 	}
 	defer closer.Close()
 
-	_, mounted, err := w.initiateUpload(expectedMountRepo, h.String())
+	_, mounted, err := w.initiateUpload(expectedMountRepo, h.String(), "")
+	if err != nil {
+		t.Errorf("intiateUpload() = %v", err)
+	}
+	if !mounted {
+		t.Error("initiateUpload() = !mounted, want mounted")
+	}
+}
+
+func TestInitiateUploadMountsWithOrigin(t *testing.T) {
+	img := setupImage(t)
+	h := mustConfigName(t, img)
+	expectedMountRepo := "a/different/repo"
+	expectedRepo := "yet/again"
+	expectedPath := fmt.Sprintf("/v2/%s/blobs/uploads/", expectedRepo)
+	expectedOrigin := "fakeOrigin"
+	expectedQuery := url.Values{
+		"mount":  []string{h.String()},
+		"from":   []string{expectedMountRepo},
+		"origin": []string{expectedOrigin},
+	}.Encode()
+
+	serverHandler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.Method != http.MethodPost {
+			t.Errorf("Method; got %v, want %v", r.Method, http.MethodPost)
+		}
+		if r.URL.Path != expectedPath {
+			t.Errorf("URL; got %v, want %v", r.URL.Path, expectedPath)
+		}
+		if r.URL.RawQuery != expectedQuery {
+			t.Errorf("RawQuery; got %v, want %v", r.URL.RawQuery, expectedQuery)
+		}
+		http.Error(w, "Mounted", http.StatusCreated)
+	})
+	server := httptest.NewServer(serverHandler)
+
+	w, closer, err := setupWriterWithServer(server, expectedRepo)
+	if err != nil {
+		t.Fatalf("setupWriterWithServer() = %v", err)
+	}
+	defer closer.Close()
+
+	_, mounted, err := w.initiateUpload(expectedMountRepo, h.String(), "fakeOrigin")
 	if err != nil {
 		t.Errorf("intiateUpload() = %v", err)
 	}