command/build: Add -except flag

command/build/command.go

@@ -20,10 +20,12 @@ func (Command) Help() string {
 }
 
 func (c Command) Run(env packer.Environment, args []string) int {
+	var cfgExcept []string
 	var cfgOnly []string
 
 	cmdFlags := flag.NewFlagSet("build", flag.ContinueOnError)
 	cmdFlags.Usage = func() { env.Ui().Say(c.Help()) }
+	cmdFlags.Var((*stringSliceValue)(&cfgExcept), "except", "build all builds except these")
 	cmdFlags.Var((*stringSliceValue)(&cfgOnly), "only", "only build the given builds by name")
 	if err := cmdFlags.Parse(args); err != nil {
 		return 1
@@ -35,6 +37,12 @@ func (c Command) Run(env packer.Environment, args []string) int {
 		return 1
 	}
 
+	if len(cfgOnly) > 0 && len(cfgExcept) > 0 {
+		env.Ui().Error("Only one of '-except' or '-only' may be specified.\n")
+		env.Ui().Error(c.Help())
+		return 1
+	}
+
 	// Read the file into a byte array so that we can parse the template
 	log.Printf("Reading template: %s", args[0])
 	tplData, err := ioutil.ReadFile(args[0])
@@ -62,6 +70,21 @@ func (c Command) Run(env packer.Environment, args []string) int {
 	buildNames := tpl.BuildNames()
 	builds := make([]packer.Build, 0, len(buildNames))
 	for _, buildName := range buildNames {
+		if len(cfgExcept) > 0 {
+			found := false
+			for _, only := range cfgExcept {
+				if buildName == only {
+					found = true
+					break
+				}
+			}
+
+			if found {
+				log.Printf("Skipping build '%s' because specified by -except.", buildName)
+				continue
+			}
+		}
+
 		if len(cfgOnly) > 0 {
 			found := false
 			for _, only := range cfgOnly {

command/build/help.go

@@ -8,5 +8,6 @@ Usage: packer build TEMPLATE
 
 Options:
 
+  -except=foo,bar,baz        Build all builds other than these
   -only=foo,bar,baz          Only build the given builds by name
 `