Add global --experimental flag to gatekeep some features

This commit adds a global --experiemntal flag so we can start
gatekeeping some features where we know beforehand that the UX will very
likely change. It also refactors the current --platform flag to be
avaiable under this experimental flag for the moment

Signed-off-by: Marcos Lilljedahl <marcosnils@gmail.com>

cmd/dagger/cmd/common/common.go

@@ -97,12 +97,12 @@ func NewClient(ctx context.Context) *client.Client {
 		lg.Fatal().Err(err).Msg("unable to parse --cache-from options")
 	}
 
-	ep := viper.GetString("experimental-platform")
+	ep := viper.GetString("platform")
 	var p *specs.Platform
 	if len(ep) > 0 {
 		pp, err := platforms.Parse(ep)
 		if err != nil {
-			lg.Fatal().Err(err).Msg("invalid value for --experimental-platform")
+			lg.Fatal().Err(err).Msg("invalid value for --platform")
 		}
 		p = &pp
 	}

cmd/dagger/cmd/do.go

@@ -42,6 +42,11 @@ var doCmd = &cobra.Command{
 			err error
 		)
 
+		switch !viper.GetBool("experimental") {
+		case len(viper.GetString("platform")) > 0:
+			lg.Fatal().Err(err).Msg("--platform requires --experimental flag")
+		}
+
 		if f := viper.GetString("log-format"); f == "tty" || f == "auto" && term.IsTerminal(int(os.Stdout.Fd())) {
 			tty, err = logger.NewTTYOutput(os.Stderr)
 			if err != nil {
@@ -157,7 +162,7 @@ func init() {
 	doCmd.Flags().StringArrayP("with", "w", []string{}, "")
 	doCmd.Flags().StringP("plan", "p", ".", "Path to plan (defaults to current directory)")
 	doCmd.Flags().Bool("no-cache", false, "Disable caching")
-	doCmd.Flags().String("experimental-platform", "", "Set target build platform (experimental)")
+	doCmd.Flags().String("platform", "", "Set target build platform (requires experimental)")
 	doCmd.Flags().StringArray("cache-to", []string{},
 		"Cache export destinations (eg. user/app:cache, type=local,dest=path/to/dir)")
 	doCmd.Flags().StringArray("cache-from", []string{},

cmd/dagger/cmd/root.go

@@ -23,6 +23,7 @@ var rootCmd = &cobra.Command{
 func init() {
 	rootCmd.PersistentFlags().String("log-format", "auto", "Log format (auto, plain, tty, json)")
 	rootCmd.PersistentFlags().StringP("log-level", "l", "info", "Log level")
+	rootCmd.PersistentFlags().Bool("experimental", false, "Enable experimental features")
 
 	rootCmd.PersistentPreRun = func(cmd *cobra.Command, _ []string) {
 		go checkVersion()