I have following cobra command

func init() {
	rootCmd.AddCommand(serveCmd)

	serveCmd.Flags().String("listenAddr", ":5000", "server listen address")
	viper.BindPFlag("server.listenaddr", serveCmd.Flags().Lookup("listenAddr"))
}

Now when I run the command I try to get the config value.

listenAddr := viper.Sub("server").GetString("listenaddr")

When running this command I see that the config value is not updated based on Env variable or commandline option.

$ ./my-app serve
listenAddr = :5000
$ ./my-app serve --listenAddr :6000
listenAddr = :5000
$ SERVER_LISTENADDR=:6000 ./my-app serve
listenAddr = :5000

However when changing the code to read the value as following it does work as expected.

listenAddr := viper.GetString("server.listenaddr")

$ ./my-app serve
listenAddr = :5000
$ ./my-app serve --listenAddr :6000
listenAddr = :6000
$ SERVER_LISTENADDR=:8888./my-app serve
listenAddr = :8888

It would be excepted that the Sub viper will also have the correct values for the config. So I can pass the subviper to the package that depends on those configs.