always add but hide experimental cmds and flags

Signed-off-by: Victor Vieux <vieux@docker.com>

docker.go

@@ -3,6 +3,7 @@ package main
 import (
 	"fmt"
 	"os"
+	"strings"
 
 	"github.com/Sirupsen/logrus"
 	"github.com/docker/docker/cli"
@@ -33,7 +34,8 @@ func newDockerCommand(dockerCli *command.DockerCli) *cobra.Command {
 				showVersion()
 				return nil
 			}
-			fmt.Fprintf(dockerCli.Err(), "\n"+cmd.UsageString())
+			cmd.SetOutput(dockerCli.Err())
+			cmd.HelpFunc()(cmd, args)
 			return nil
 		},
 		PersistentPreRunE: func(cmd *cobra.Command, args []string) error {
@@ -45,6 +47,22 @@ func newDockerCommand(dockerCli *command.DockerCli) *cobra.Command {
 	}
 	cli.SetupRootCommand(cmd)
 
+	cmd.SetHelpFunc(func(ccmd *cobra.Command, args []string) {
+		var err error
+		if dockerCli.Client() == nil {
+			// flags must be the top-level command flags, not cmd.Flags()
+			opts.Common.SetDefaultOptions(flags)
+			dockerPreRun(opts)
+			err = dockerCli.Initialize(opts)
+		}
+		if err != nil || !dockerCli.HasExperimental() {
+			hideExperimentalFeatures(ccmd)
+		}
+		if err := ccmd.Help(); err != nil {
+			ccmd.Println(err)
+		}
+	})
+
 	flags = cmd.Flags()
 	flags.BoolVarP(&opts.Version, "version", "v", false, "Print version information and quit")
 	flags.StringVar(&opts.ConfigDir, "config", cliconfig.ConfigDir(), "Location of client config files")
@@ -105,3 +123,20 @@ func dockerPreRun(opts *cliflags.ClientOptions) {
 		utils.EnableDebug()
 	}
 }
+
+func hideExperimentalFeatures(cmd *cobra.Command) {
+	// hide flags
+	cmd.Flags().VisitAll(func(f *pflag.Flag) {
+		if _, ok := f.Annotations["experimental"]; ok {
+			f.Hidden = true
+		}
+	})
+
+	for _, subcmd := range cmd.Commands() {
+		// hide subcommands
+		name := strings.Split(subcmd.Use, " ")[0]
+		if name == "stack" || name == "deploy" || name == "checkpoint" || name == "plugin" {
+			subcmd.Hidden = true
+		}
+	}
+}