Use Cobra built-in --version feature

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

cli/cobra.go

@@ -23,6 +23,7 @@ func SetupRootCommand(rootCmd *cobra.Command) {
 	rootCmd.SetHelpTemplate(helpTemplate)
 	rootCmd.SetFlagErrorFunc(FlagErrorFunc)
 	rootCmd.SetHelpCommand(helpCommand)
+	rootCmd.SetVersionTemplate("Docker version {{.Version}}\n")
 
 	rootCmd.PersistentFlags().BoolP("help", "h", false, "Print usage")
 	rootCmd.PersistentFlags().MarkShorthandDeprecated("help", "please use --help")

cli/flags/client.go

@@ -4,7 +4,6 @@ package flags
 type ClientOptions struct {
 	Common    *CommonOptions
 	ConfigDir string
-	Version   bool
 }
 
 // NewClientOptions returns a new ClientOptions

cmd/docker/docker.go

@@ -32,13 +32,6 @@ func newDockerCommand(dockerCli *command.DockerCli) *cobra.Command {
 		SilenceErrors:    true,
 		TraverseChildren: true,
 		Args:             noArgs,
-		RunE: func(cmd *cobra.Command, args []string) error {
-			if opts.Version {
-				showVersion()
-				return nil
-			}
-			return command.ShowHelp(dockerCli.Err())(cmd, args)
-		},
 		PersistentPreRunE: func(cmd *cobra.Command, args []string) error {
 			// flags must be the top-level command flags, not cmd.Flags()
 			opts.Common.SetDefaultOptions(flags)
@@ -48,11 +41,12 @@ func newDockerCommand(dockerCli *command.DockerCli) *cobra.Command {
 			}
 			return isSupported(cmd, dockerCli)
 		},
+		Version: fmt.Sprintf("%s, build %s", cli.Version, cli.GitCommit),
 	}
 	cli.SetupRootCommand(cmd)
 
 	flags = cmd.Flags()
-	flags.BoolVarP(&opts.Version, "version", "v", false, "Print version information and quit")
+	flags.BoolP("version", "v", false, "Print version information and quit")
 	flags.StringVar(&opts.ConfigDir, "config", cliconfig.Dir(), "Location of client config files")
 	opts.Common.InstallFlags(flags)
 
@@ -186,10 +180,6 @@ func contentTrustEnabled() bool {
 	return false
 }
 
-func showVersion() {
-	fmt.Printf("Docker version %s, build %s\n", cli.Version, cli.GitCommit)
-}
-
 func dockerPreRun(opts *cliflags.ClientOptions) {
 	cliflags.SetLogLevel(opts.Common.LogLevel)