Fix up mutable_source interface a bit more to make it usable from outside this package. (#190)

Author: dlorenc

pkg/image/mutable_source.go

@@ -61,18 +61,21 @@ func NewMutableSource(r types.ImageReference) (*MutableSource, error) {
 	return ms, nil
 }
 
-// GetManifest marshals the stored manifest to the byte format.
+// Manifest marshals the stored manifest to the byte format.
 func (m *MutableSource) GetManifest(_ *digest.Digest) ([]byte, string, error) {
-	s, err := json.Marshal(m.mfst)
 	if err := m.saveConfig(); err != nil {
 		return nil, "", err
 	}
+	s, err := json.Marshal(m.mfst)
+	if err != nil {
+		return nil, "", err
+	}
 	return s, manifest.DockerV2Schema2MediaType, err
 }
 
 // populateManifestAndConfig parses the raw manifest and configs, storing them on the struct.
 func (m *MutableSource) populateManifestAndConfig() error {
-	mfstBytes, _, err := m.GetManifest(nil)
+	mfstBytes, _, err := m.ProxySource.GetManifest(nil)
 	if err != nil {
 		return err
 	}
@@ -116,7 +119,7 @@ func gzipBytes(b []byte) ([]byte, error) {
 }
 
 // appendLayer appends an uncompressed blob to the image, preserving the invariants required across the config and manifest.
-func (m *MutableSource) appendLayer(content []byte) error {
+func (m *MutableSource) AppendLayer(content []byte) error {
 	compressedBlob, err := gzipBytes(content)
 	if err != nil {
 		return err

pkg/image/mutable_source_test.go

@@ -68,7 +68,7 @@ var testCases = []struct {
 	},
 }
 
-func TestMutableSource_appendLayer(t *testing.T) {
+func TestMutableSource_AppendLayer(t *testing.T) {
 	for _, tt := range testCases {
 		t.Run(tt.name, func(t *testing.T) {
 			m := &MutableSource{
@@ -77,8 +77,8 @@ func TestMutableSource_appendLayer(t *testing.T) {
 				extraBlobs: make(map[string][]byte),
 			}
 
-			if err := m.appendLayer([]byte(tt.args.content)); (err != nil) != tt.wantErr {
-				t.Fatalf("MutableSource.appendLayer() error = %v, wantErr %v", err, tt.wantErr)
+			if err := m.AppendLayer([]byte(tt.args.content)); (err != nil) != tt.wantErr {
+				t.Fatalf("MutableSource.AppendLayer() error = %v, wantErr %v", err, tt.wantErr)
 			}
 			if err := m.saveConfig(); err != nil {
 				t.Fatalf("Error saving config: %v", err)

pkg/image/proxy_types.go

@@ -55,13 +55,9 @@ func (p *ProxySource) LayerInfosForCopy() []types.BlobInfo {
 // ProxyReference implements types.Reference by proxying calls to an underlying implementation.
 type ProxyReference struct {
 	types.ImageReference
-	src types.ImageSource
+	Src types.ImageSource
 }
 
 func (p *ProxyReference) NewImageSource(ctx *types.SystemContext) (types.ImageSource, error) {
-	return p.src, nil
-}
-
-func (p *ProxyReference) NewImageDestination(ctx *types.SystemContext) (types.ImageDestination, error) {
-	return p.ImageReference.NewImageDestination(ctx)
+	return p.Src, nil
 }