'docker commit' can optionally tag the new image into a repository

Upstream-commit: 8396798ebae99791ce3f2f43c276af8e6b96d782
Component: engine

components/engine/runtime.go

@@ -200,6 +200,33 @@ func (runtime *Runtime) Destroy(container *Container) error {
 	return nil
 }
 
+// Commit creates a new filesystem image from the current state of a container.
+// The image can optionally be tagged into a repository
+func (runtime *Runtime) Commit(id, repository, tag string) (*Image, error) {
+	container := runtime.Get(id)
+	if container == nil {
+		return nil, fmt.Errorf("No such container: %s", id)
+	}
+	// FIXME: freeze the container before copying it to avoid data corruption?
+	// FIXME: this shouldn't be in commands.
+	rwTar, err := container.ExportRw()
+	if err != nil {
+		return nil, err
+	}
+	// Create a new image from the container's base layers + a new layer from container changes
+	img, err := runtime.graph.Create(rwTar, container.Image, "")
+	if err != nil {
+		return nil, err
+	}
+	// Register the image if needed
+	if repository != "" {
+		if err := runtime.repositories.Set(repository, tag, img.Id); err != nil {
+			return img, err
+		}
+	}
+	return img, nil
+}
+
 func (runtime *Runtime) restore() error {
 	dir, err := ioutil.ReadDir(runtime.repository)
 	if err != nil {