[option] fix print helper msg twice bug

pkg/option/option.go

@@ -43,6 +43,7 @@ type Options struct {
 
  // Flags from command line only.
  ShowVersion bool `yaml:"-"`
+ ShowHelp bool `yaml:"-"`
  ShowConfig bool `yaml:"-"`
  ConfigFile string `yaml:"-"`
  ForceNewCluster bool `yaml:"-"`
@@ -90,6 +91,7 @@ func New() *Options {
  }
 
  opt.flags.BoolVarP(&opt.ShowVersion, "version", "v", false, "Print the version and exit.")
+ opt.flags.BoolVarP(&opt.ShowHelp, "help", "h", false, "Print the helper message and exit.")
  opt.flags.BoolVarP(&opt.ShowConfig, "print-config", "c", false, "Print the configuration.")
  opt.flags.StringVarP(&opt.ConfigFile, "config-file", "f", "", "Load server configuration from a file(yaml format), other command line flags will be ignored if specified.")
  opt.flags.BoolVar(&opt.ForceNewCluster, "force-new-cluster", false, "Force to create a new one-member cluster.")
@@ -129,17 +131,17 @@ func (opt *Options) YAML() string {
 func (opt *Options) Parse() (string, error) {
  err := opt.flags.Parse(os.Args[1:])
  if err != nil {
- if err == pflag.ErrHelp {
- return opt.flags.FlagUsages(), nil
- } else {
- return "", nil
- }
+ return "", err
  }
 
  if opt.ShowVersion {
  return version.Short, nil
  }
 
+ if opt.ShowHelp {
+ return opt.flags.FlagUsages(), nil
+ }
+
  opt.viper.AutomaticEnv()
  opt.viper.SetEnvPrefix("EG")
  opt.viper.SetEnvKeyReplacer(strings.NewReplacer("-", "_"))