How to make it works for subcommands

[rgarrigue]

Hi there

Long story short, I started from cobra-cli boilerplate, and taking snippets of this repository I got a root command working.

But my issue now is that subcommands don't take env / config file in account, just flags. After trials & errors, seems I would need to add ViperCfg.ReadInConfig() in all the subcommands' init. Not really elegant, I guess I'm missing something as PersistentPreRun should propagate the viper config reading. But well, beginner's struggles.

So wondering what I'm missing here / how would you deal with subcommands in your setup ?

Here's my root.go

package cmd

import (
	"fmt"
	"os"
	"strings"
	"time"

	"github.com/rs/zerolog"
	"github.com/rs/zerolog/log"
	"github.com/spf13/cobra"
	"github.com/spf13/pflag"
	"github.com/spf13/viper"
)

var logLevel string

var rootCmd = &cobra.Command{
	Use:   "tool",
	Short: "tool is a tool.",
	Long:  `tool allow you to .`,
	PersistentPreRun: func(cmd *cobra.Command, args []string) {

		if strings.ToLower(logFormat) == "text" {
			log.Logger = log.Output(zerolog.ConsoleWriter{Out: os.Stderr, TimeFormat: time.RFC3339}).
				With().
				Timestamp().
				Caller().
				Logger()
		}

		switch strings.ToLower(logLevel) {
		case "trace":
			zerolog.SetGlobalLevel(zerolog.TraceLevel)
		}
	},
}

func Execute() {
	err := rootCmd.Execute()
	if err != nil {
		os.Exit(1)
	}
}

func init() {
	cobra.OnInitialize(initializeConfig)

	rootCmd.PersistentFlags().StringVarP(&configFile, "config", "c", "", "Configuration file (default /etc/tool/config.yaml > $HOME/.tool/config.yaml > ./.config.yaml)")
	rootCmd.PersistentFlags().StringVarP(&logLevel, "loglevel", "l", "INFO", "Log level. From the less verbose to the most, panic, fatal, error, warn, info, debug, trace")
}

var viperCfg viper.Viper

func initializeConfig() {
	viperCfg = *viper.New()

	if configFile != "" {
		viperCfg.SetConfigFile(configFile)
	} else {
		viperCfg.SetConfigName("config")

		home, _ := os.UserHomeDir()
		viperCfg.AddConfigPath(".")
		viperCfg.AddConfigPath(home + ".config/tool")
		viperCfg.AddConfigPath("/etc/tool")
	}

	if err := viperCfg.ReadInConfig(); err != nil {
		if _, ok := err.(viper.ConfigFileNotFoundError); !ok {
			log.Fatal().Msgf("Couldn't parse configuration file %s", viperCfg.ConfigFileUsed())
		}
	}

	viperCfg.SetEnvKeyReplacer(strings.NewReplacer("-", "_"))
	viperCfg.AutomaticEnv()

	bindFlags()
}

func bindFlags() {
	rootCmd.Flags().VisitAll(func(f *pflag.Flag) {
		configName := f.Name
		
		if !f.Changed && viperCfg.IsSet(configName) {
			val := viperCfg.Get(configName)
			rootCmd.Flags().Set(f.Name, fmt.Sprintf("%v", val))
		}
	})
}

And the shortened generate.go

package cmd

import (	
	"os"
	"strings"

	"github.com/rs/zerolog/log"
	"github.com/spf13/cobra"
)

var valuesFile string

var generateCmd = &cobra.Command{
	Use:   "generate",
	Short: "Generate",
	Long: `Create the
	`,
	Run: generate,
}

func init() {
	rootCmd.AddCommand(generateCmd)

	generateCmd.Flags().StringVarP(&valuesFile, "values", "f", "./values.yaml", "Path of the")

        // insert ViperCfg.ReadInConfig() to get the config file settings taken in account
}

func generate(cmd *cobra.Command, args []string) {
	
	_, errVal := os.Stat(valuesFiles)
	if os.IsNotExist(errVal) {
		log.Fatal().Msgf("Values file '%s' doesn't exist", valuesFiles)
	}

	// ...
}

[rgarrigue]

@carolynvs sorry for bothering you, but back on the topic and still stuck, so any help would be welcomed 😖

[carolynvs]

Hey @rgarrigue I can't provide support / troubleshooting for cobra. But I can point you towards my codebase, https://github.com/getporter/porter/blob/main/cmd/porter/main.go and https://github.com/getporter/porter/blob/main/pkg/cli/config.go (helpers for cobra) which works with subcommands and everything outlined in stingoftheviper.

Hopefully that helps give you an idea of what's different that is causing your subcommands to not work! 👍

[Inveracity]

This is how I ended up solving it

package main

import (
	"fmt"
	"os"
	"strings"

	"github.com/spf13/cobra"
	"github.com/spf13/pflag"
	"github.com/spf13/viper"
)

type App struct {
}

func main() {
	cli := New()
	cli.HelloCli()
}

func New() *App {
	return &App{}
}

func (c *App) HelloCli() {

	rootCmd := &cobra.Command{
		Use:   "do",
		Short: "do things",
		PersistentPreRunE: func(cmd *cobra.Command, args []string) error {
			return InitializeConfig(cmd)
		},
		Run: func(cmd *cobra.Command, args []string) {
			cmd.Help()
		},
	}

	hello := rootCmd.PersistentFlags().String("hello", "name", "your name")
	rootCmd.AddCommand((&DoStuff{}).Hello(hello))
	err := rootCmd.Execute()
	if err != nil {
		os.Exit(1)
	}
}

type DoStuff struct {
}

func (c *DoStuff) Hello(hello *string) *cobra.Command {
	cmd := &cobra.Command{
		Use:   "hello",
		Short: "say hello",
		Run: func(cmd *cobra.Command, args []string) {
			fmt.Printf("hello %s\n", *hello)
		},
	}

	return cmd
}

func InitializeConfig(cmd *cobra.Command) error {
	v := viper.New()
	v.SetEnvPrefix("MYCLI")
	v.SetEnvKeyReplacer(strings.NewReplacer("-", "_"))
	v.AutomaticEnv()
	bindFlags(cmd, v)
	return nil
}

// Bind each cobra flag to its associated viper configuration environment variable
func bindFlags(cmd *cobra.Command, v *viper.Viper) {
	cmd.Flags().VisitAll(func(f *pflag.Flag) {
		configName := f.Name
		if !f.Changed && v.IsSet(configName) {
			val := v.Get(configName)
			cmd.Flags().Set(f.Name, fmt.Sprintf("%v", val))
		}
	})
}

MYCLI_HELLO=bob go run main.go hello
# hello bob
go run main.go hello --hello=world
# hello world