Make "docker insert" errors obvious

Closes moby#1130
See also moby#1942

api.go

@@ -479,15 +479,12 @@ func postImagesInsert(srv *Server, version float64, w http.ResponseWriter, r *ht
 		w.Header().Set("Content-Type", "application/json")
 	}
 	sf := utils.NewStreamFormatter(version > 1.0)
-	imgID, err := srv.ImageInsert(name, url, path, w, sf)
+	err := srv.ImageInsert(name, url, path, w, sf)
 	if err != nil {
-		if sf.Used() {
-			w.Write(sf.FormatError(err))
-			return nil
-		}
+		w.Write(sf.FormatError(err))
 	}
 
-	return writeJSON(w, http.StatusOK, &APIID{ID: imgID})
+	return nil
 }
 
 func postImagesPush(srv *Server, version float64, w http.ResponseWriter, r *http.Request, vars map[string]string) error {

commands.go

@@ -130,10 +130,7 @@ func (cli *DockerCli) CmdInsert(args ...string) error {
 	v.Set("url", cmd.Arg(1))
 	v.Set("path", cmd.Arg(2))
 
-	if err := cli.stream("POST", "/images/"+cmd.Arg(0)+"/insert?"+v.Encode(), nil, cli.out, nil); err != nil {
-		return err
-	}
-	return nil
+	return cli.stream("POST", "/images/"+cmd.Arg(0)+"/insert?"+v.Encode(), nil, cli.out, nil)
 }
 
 // mkBuildContext returns an archive of an empty context with the contents

server.go

@@ -198,39 +198,39 @@ func (srv *Server) ImagesSearch(term string) ([]registry.SearchResult, error) {
 	return results.Results, nil
 }
 
-func (srv *Server) ImageInsert(name, url, path string, out io.Writer, sf *utils.StreamFormatter) (string, error) {
+func (srv *Server) ImageInsert(name, url, path string, out io.Writer, sf *utils.StreamFormatter) error {
 	out = utils.NewWriteFlusher(out)
 	img, err := srv.runtime.repositories.LookupImage(name)
 	if err != nil {
-		return "", err
+		return err
 	}
 
 	file, err := utils.Download(url, out)
 	if err != nil {
-		return "", err
+		return err
 	}
 	defer file.Body.Close()
 
 	config, _, _, err := ParseRun([]string{img.ID, "echo", "insert", url, path}, srv.runtime.capabilities)
 	if err != nil {
-		return "", err
+		return err
 	}
 
 	c, _, err := srv.runtime.Create(config, "")
 	if err != nil {
-		return "", err
+		return err
 	}
 
-	if err := c.Inject(utils.ProgressReader(file.Body, int(file.ContentLength), out, sf.FormatProgress("", "Downloading", "%8v/%v (%v)"), sf, true), path); err != nil {
-		return "", err
+	if err := c.Inject(utils.ProgressReader(file.Body, int(file.ContentLength), out, sf.FormatProgress("", "Downloading", "%8v/%v (%v)"), sf, false), path); err != nil {
+		return err
 	}
 	// FIXME: Handle custom repo, tag comment, author
 	img, err = srv.runtime.Commit(c, "", "", img.Comment, img.Author, nil)
 	if err != nil {
-		return "", err
+		return err
 	}
-	out.Write(sf.FormatStatus("", img.ID))
-	return img.ShortID(), nil
+	out.Write(sf.FormatStatus(utils.TruncateID(img.ID), "Image created"))
+	return nil
 }
 
 func (srv *Server) ImagesViz(out io.Writer) error {