Snippet of Cobra and Viper tag-team

main.go

func init() {
 	cobra.OnInitialize(initConfig)
 
 	viper.SetEnvPrefix("VOYAGER")
 	viper.SetEnvKeyReplacer(strings.NewReplacer(".", "_"))
 	viper.AutomaticEnv()
 
 	rootCmd.PersistentFlags().StringVar(&cfgFile, "config", "", "config file (default is $HOME/.voyager.yaml)")
 
 	rootCmd.PersistentFlags().BoolP("debug", "d", false, "Enable debug logging")
 	viper.BindPFlag("debug", rootCmd.PersistentFlags().Lookup("debug"))
 	viper.BindEnv("debug", "DEBUG")
 
 	rootCmd.PersistentFlags().StringP("database-url", "", "", "Database URL")
 	viper.BindPFlag("database-url", rootCmd.PersistentFlags().Lookup("database-url"))
 	viper.BindEnv("database-url", "DATABASE_URL")
 }
 
 func initConfig() {
 	if cfgFile != "" {
 		// Use config file from the flag.
 		viper.SetConfigFile(cfgFile)
 	} else {
 		// Find home directory.
 		home, err := os.UserHomeDir()
 		if err != nil {
 			log.Fatal().Err(err).Msg("could not get home directory")
 		}
 
 		// Search config in home directory with name ".cobra" (without extension).
 		viper.AddConfigPath(home)
 		viper.SetConfigType("yaml")
 		viper.SetConfigName(".voyager")
 	}
 
 	viper.AutomaticEnv()
 
 	logLevel := zerolog.InfoLevel
 	if viper.GetBool("debug") {
 		logLevel = zerolog.DebugLevel
 	}
 	zerolog.SetGlobalLevel(logLevel)
 
 	if err := viper.ReadInConfig(); err != nil {
 		if _, ok := err.(viper.ConfigFileNotFoundError); !ok {
 			log.Fatal().Err(err).Msg("could not read configuration file")
 		}
 	}
 }