Debug cobra duplicated flags

main.go

package main

import (
	"github.com/spf13/cobra"
	"github.com/spf13/viper"
)

var v = viper.New()

func NewCommand() *cobra.Command {
	cmd := &cobra.Command{
		Use: "demo SUBCOMMAND",
	}

	cmd.AddCommand(NewSubCmd1())
	cmd.AddCommand(NewSubCmd2())

	return cmd
}

func NewSubCmd1() *cobra.Command {
	cmd := &cobra.Command{
		Use: "cmd1",
		Run: func(cmd *cobra.Command, args []string) {
			println("cmd1", "log.level =", v.GetString("log.level"))
		},
	}

	cmd.PersistentFlags().String("log-level", "info", "Logger's output level")
	_ = v.BindPFlag("log.level", cmd.Flag("log-level"))

	return cmd
}

func NewSubCmd2() *cobra.Command {
	cmd := &cobra.Command{
		Use: "cmd2",
		Run: func(cmd *cobra.Command, args []string) {
			println("cmd2", "log.level =", v.GetString("log.level"))
		},
	}

	cmd.PersistentFlags().String("log-level", "info", "Logger's output level")
	_ = v.BindPFlag("log.level", cmd.Flag("log-level"))

	return cmd
}

func main() {
	command := NewCommand()
	if err := command.Execute(); err != nil {
		panic(err)
	}
}

// $ go run . cmd1 --log-level debug
// cmd1 log.level = info
//
// $ go run . cmd2 --log-level debug
// cmd2 log.level = debug