Add a --name cli option to the moby tool

This sets the base name of the built images which otherwise
defaults to the basename of your yaml file. This allows
building different versions easily eg adding git sha to the
output names.

Signed-off-by: Justin Cormack <justin.cormack@docker.com>

main.go

@@ -156,7 +156,7 @@ func containersInitrd(containers []*bytes.Buffer) (*bytes.Buffer, error) {
 	return w, nil
 }
 
-func build(m *Moby) {
+func build(m *Moby, name string) {
 	containers := []*bytes.Buffer{}
 
 	// get kernel bzImage and initrd tarball from container
@@ -216,13 +216,7 @@ func build(m *Moby) {
 		log.Fatalf("Failed to make initrd %v", err)
 	}
 
-	base := filepath.Base(conf)
-	ext := filepath.Ext(conf)
-	if ext != "" {
-		base = base[:len(base)-len(ext)]
-	}
-
-	err = outputs(m, base, bzimage.Bytes(), initrd.Bytes())
+	err = outputs(m, name, bzimage.Bytes(), initrd.Bytes())
 	if err != nil {
 		log.Fatalf("Error writing outputs: %v", err)
 	}
@@ -231,10 +225,12 @@ func build(m *Moby) {
 var (
 	conf    string
 	cmdline bool
+	name    string
 )
 
 func main() {
 	flag.BoolVar(&cmdline, "cmdline", false, "Print the kernel command line and exit")
+	flag.StringVar(&name, "name", "", "Name to use for output files")
 	flag.Parse()
 
 	conf = "moby.yaml"
@@ -242,6 +238,14 @@ func main() {
 		conf = flag.Args()[0]
 	}
 
+	if name == "" {
+		name = filepath.Base(conf)
+		ext := filepath.Ext(conf)
+		if ext != "" {
+			name = name[:len(name)-len(ext)]
+		}
+	}
+
 	config, err := ioutil.ReadFile(conf)
 	if err != nil {
 		log.Fatalf("Cannot open config file: %v", err)
@@ -257,5 +261,5 @@ func main() {
 		return
 	}
 
-	build(m)
+	build(m, name)
 }