[config] preliminary Dockerfile support

plugins/config/src/configenv/configenv.go

@@ -37,12 +37,13 @@ func (e *Env) stringWithEntryPrefix(prefix string) string {
 	sort.Strings(keys)
 	entries := make([]string, len(keys))
 	for i, k := range keys {
-		entries[i] = fmt.Sprintf("%s%s='%s'", prefix, k, singleQuoteEscape(e.env[k]))
+		entries[i] = fmt.Sprintf("%s%s='%s'", prefix, k, SingleQuoteEscape(e.env[k]))
 	}
 	return strings.Join(entries, "\n")
 }
 
-func singleQuoteEscape(value string) string { // so that 'esc'apped' -> 'esc'\''aped'
+//SingleQuoteEscape escapes the value as if it were shell-quoted in single quotes
+func SingleQuoteEscape(value string) string { // so that 'esc'apped' -> 'esc'\''aped'
 	return strings.Replace(value, "'", "'\\''", -1)
 }
 

plugins/config/src/subcommands/export/export.go

@@ -13,6 +13,7 @@ import (
 func main() {
 	args := flag.NewFlagSet("config:export", flag.ExitOnError)
 	global := args.Bool("global", false, "--global: use the global environment")
+	keys := args.Bool("keys", false, "--keys: export keys only")
 	envfile := args.Bool("envfile", false, "--envfile: export as envfile rather than bash exports")
 	args.Parse(os.Args[2:])
 
@@ -32,6 +33,13 @@ func main() {
 	if err != nil {
 		common.LogFail(err.Error())
 	}
+	if *keys {
+		for _, k := range env.Keys() {
+			fmt.Println(k)
+		}
+		return
+	}
+
 	if *envfile {
 		fmt.Println(env.EnvfileString())
 	} else {

plugins/config/src/subcommands/get/get.go

@@ -13,6 +13,7 @@ import (
 func main() {
 	args := flag.NewFlagSet("config:get", flag.ExitOnError)
 	global := args.Bool("global", false, "--global: use the global environment")
+	quoted := args.Bool("quoted", false, "--quoted: get the value quoted")
 	args.Parse(os.Args[2:])
 	appName := args.Arg(0)
 	nextArg := 0
@@ -35,5 +36,10 @@ func main() {
 		common.LogFail(fmt.Sprintf("Unexpected argument(s): %v", args.Args()[nextArg+1:]))
 	}
 	key := args.Arg(nextArg)
-	fmt.Printf("%s", env.GetDefault(key, ""))
+	value := env.GetDefault(key, "")
+	if *quoted {
+		fmt.Printf("'%s'", configenv.SingleQuoteEscape(value))
+	} else {
+		fmt.Printf("%s", value)
+	}
 }