Cobra Subcommand Invoke Help By Default

I think it is better to handle that on PreRunE.

var addonCmd = &cobra.Command{
    Use:   "addon",
    Short: "Install addon packages",
    Long: `Install additional packages`,
    PreRunE: func(cmd *cobra.Command, args []string) error {
        if len(args) == 0 {
            cmd.Help()
            os.Exit(0)
        }
        return nil
    },
    Run: func(cmd *cobra.Command, args []string) {
        // do actual work
    },
}

It is possible to do with checking of amount of passed arguments to your program. If there is more then 0 args you will do actual work, but if it less then you will just show the "help" for the command.

var addonCmd = &cobra.Command{
    Use:   "addon",
    Short: "Install addon packages",
    Long: `Install additional packages`,
    Run: func(cmd *cobra.Command, args []string) {
        if len(args) == 0 {
            cmd.Help()
            os.Exit(0)
        }
        // do actual work
    },
}