add simple ConfigFile() support for schema1

Signed-off-by: Matthias Bertschy <[email protected]>

Author: matthyx

pkg/v1/remote/schema1.go

@@ -71,7 +71,23 @@ func (s *schema1) ConfigName() (v1.Hash, error) {
 }
 
 func (s *schema1) ConfigFile() (*v1.ConfigFile, error) {
-	return nil, newErrSchema1(s.mediaType)
+	configFile := &v1.ConfigFile{
+		RootFS: v1.RootFS{
+			Type: "layers",
+		},
+	}
+	layers, err := s.Layers()
+	if err != nil {
+		return nil, err
+	}
+	for _, layer := range layers {
+		d, err := layer.Digest()
+		if err != nil {
+			return nil, err
+		}
+		configFile.RootFS.DiffIDs = append(configFile.RootFS.DiffIDs, d)
+	}
+	return configFile, nil
 }
 
 func (s *schema1) RawConfigFile() ([]byte, error) {

pkg/v1/remote/schema1_test.go

@@ -113,7 +113,17 @@ func TestSchema1(t *testing.T) {
 		}
 	}
 
-	mustErr(img.ConfigFile())
+	config, err := img.ConfigFile()
+	if err != nil {
+		t.Fatalf("Error loading config file: %v", err)
+	}
+	if got, want := len(config.RootFS.DiffIDs), 3; got != want {
+		t.Fatalf("num diff ids; got %v, want %v", got, want)
+	}
+	if got, want := config.RootFS.Type, "layers"; got != want {
+		t.Fatalf("rootfs type; got %v, want %v", got, want)
+	}
+
 	mustErr(img.Manifest())
 	mustErr(img.LayerByDiffID(v1.Hash{}))