Adds cross-repository blob pushing behavior

Tracks source repository information for each blob in the blobsum
service, which is then used to attempt to mount blobs from another
repository when pushing instead of having to re-push blobs to the same
registry.

Signed-off-by: Brian Bland <brian.bland@docker.com>
Upstream-commit: 7289c7218e2101eb94fb90f2cb22e1412d016984
Component: engine

components/engine/migrate/v1/migratev1.go

@@ -477,7 +477,7 @@ func migrateImage(id, root string, ls graphIDRegistrar, is image.Store, ms metad
 		dgst, err := digest.ParseDigest(string(checksum))
 		if err == nil {
 			blobSumService := metadata.NewBlobSumService(ms)
-			blobSumService.Add(layer.DiffID(), dgst)
+			blobSumService.Add(layer.DiffID(), metadata.BlobSum{Digest: dgst})
 		}
 	}
 	_, err = ls.Release(layer)

components/engine/migrate/v1/migratev1_test.go

@@ -216,9 +216,9 @@ func TestMigrateImages(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	expectedBlobsums := []digest.Digest{
-		"sha256:55dc925c23d1ed82551fd018c27ac3ee731377b6bad3963a2a4e76e753d70e57",
-		"sha256:a3ed95caeb02ffe68cdd9fd84406680ae93d633cb16422d00e8a7c22955b46d4",
+	expectedBlobsums := []metadata.BlobSum{
+		{Digest: digest.Digest("sha256:55dc925c23d1ed82551fd018c27ac3ee731377b6bad3963a2a4e76e753d70e57")},
+		{Digest: digest.Digest("sha256:a3ed95caeb02ffe68cdd9fd84406680ae93d633cb16422d00e8a7c22955b46d4")},
 	}
 
 	if !reflect.DeepEqual(expectedBlobsums, blobsums) {