Trouble using Cobra/Viper

Question

I'm having trouble using Cobra and Viper together. This is what I'm doing:

var options util.Config = util.Config{}
var rootCmd = &cobra.Command{
    Use:   "test [command] [subcommands]",
    Run: func(cmd *cobra.Command, args []string) {
        if err := server.Run(); err != nil {
            l.Fatal(err)
        }
    },
}

// initConfig helps initialise configuration with a stated path
func initConfig() {
    if options.Path != "" {
        viper.SetConfigFile(options.Path)
    }
    viper.AutomaticEnv()
    if err := viper.ReadInConfig(); err != nil {
        fmt.Println("Could not use config file: ", viper.ConfigFileUsed())
    }
}

func init() {
    cobra.OnInitialize(initConfig)
    rootCmd.PersistentFlags().StringVarP(&options.Path, "config", "n", "", "Path of a configuration file")
    rootCmd.PersistentFlags().StringVarP(&options.Password, "password", "d", "", "Password to access the server")
    viper.BindPFlag("password", rootCmd.PersistentFlags().Lookup("password"))
    rootCmd.AddCommand(log.Cmd(&options))
}

func main() {
    rootCmd.Execute()
}

I'm trying to retrieve the value options.Password within my subcommand (an added command within log.Cmd(&options)) however the field isn't being populated. I'm pretty sure I'm following the Cobra docs properly: https://github.com/spf13/cobra#create-rootcmd

Answer 1

Binding cobra flags to viper options only binds cobra flags to viper options, not vice versa. So you can access the password via

pass := viper.GetString("password")

if the password is set either via viper or cobra, but not via the variables defined in your flag definitions.

Basically, you have two options here: Either you use cobra without pointing your flags to variables, and then set your globals via various calls to viper.Get* (you can even sanitize them while being at it), or you use viper as sort of a „parameter registry“ and call viper.Get* where needed. I tend to go with the former solution.