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
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.
Related
is there a way of dynamically registering cobra commands based on a viper configuration file? Basically I want to only register commands that are available within my config file as "modules".
My root.go's init function looks like this
func init() {
cobra.OnInitialize(initConfig)
//don't I have access to viper.GetString("foo") here? It returns empty string instead of "bar"
registerCommandsPalette()
//disable help command
rootCmd.SetHelpCommand(&cobra.Command{
Use: "no-help",
Hidden: true,
})
//disable completion command
rootCmd.CompletionOptions.DisableDefaultCmd = true
rootCmd.PersistentFlags().StringVar(&cfgFile, "config", "", "config file (default is $HOME/.toolbox.yaml)")
}
func registerCommandsPalette() {
//here I want to access the config e.g. viper.GetString("foo")
//on various conditions I want to add a command to rootCmd.
rootCmd.AddCommand(server.ServerCmd)
rootCmd.AddCommand(net.NetCmd)
}
func initConfig() {
if cfgFile != "" {
// Use config file from the flag.
viper.SetConfigFile(cfgFile)
} else {
// Find home directory.
home, err := os.UserHomeDir()
cobra.CheckErr(err)
// Search config in home directory with name ".toolbox" (without extension).
viper.AddConfigPath(home)
viper.SetConfigType("json")
viper.SetConfigName(".toolbox")
}
viper.AutomaticEnv() // read in environment variables that match
// If a config file is found, read it in.
if err := viper.ReadInConfig(); err != nil {
fmt.Println("Could not load configuration file")
os.Exit(1)
}
}
My config file looks like this:
{
"available_modules": [
"module-1",
"module-2"
],
"foo": "bar"
//....
}
Whenever I use viper.GetString("foo") in a command file, I do get the string "bar" back.
Do you have any ideas?
Best,
Jakob
The sketch below is a command line application written using Cobra and Go. I'd like to throw an error if the value of flag1 doesn't match the regex ^\s+\/\s+. How do I do that?
package cmd
import (
"fmt"
"os"
"github.com/spf13/cobra"
homedir "github.com/mitchellh/go-homedir"
"github.com/spf13/viper"
)
var flag1 string
var cfgFile string
// rootCmd represents the base command when called without any subcommands
var rootCmd = &cobra.Command{
Use: "cobra-sketch",
Short: "Sketch for Cobra flags",
Long: "Sketch for Cobra flags",
Run: func(cmd *cobra.Command, args []string) { fmt.Printf("Flag1 is %s\n", flag1)},
}
// Execute adds all child commands to the root command and sets flags appropriately.
// This is called by main.main(). It only needs to happen once to the rootCmd.
func Execute() {
cobra.CheckErr(rootCmd.Execute())
}
func init() {
cobra.OnInitialize(initConfig)
rootCmd.PersistentFlags().StringVar(&cfgFile, "config", "", "config file (default is $HOME/.cobra-sketch.yaml)")
rootCmd.PersistentFlags().StringVar(&flag1, "flag1", "", "Value of Flag 1")
}
// initConfig reads in config file and ENV variables if set.
func initConfig() {
if cfgFile != "" {
// Use config file from the flag.
viper.SetConfigFile(cfgFile)
} else {
// Find home directory.
home, err := homedir.Dir()
cobra.CheckErr(err)
// Search config in home directory with name ".cobra-sketch" (without extension).
viper.AddConfigPath(home)
viper.SetConfigName(".cobra-sketch")
}
viper.AutomaticEnv() // read in environment variables that match
// If a config file is found, read it in.
if err := viper.ReadInConfig(); err == nil {
fmt.Fprintln(os.Stderr, "Using config file:", viper.ConfigFileUsed())
}
}
Let's say a user runs the command like this: cobra-sketch --flag1 "hello". "hello" will be stored in the var flag1 string variable you have assigned to the flag, to check if the input matches any regexp, you can do:
var rootCmd = &cobra.Command{
Use: "cobra-sketch",
...
RunE: func(cmd *cobra.Command, args []string) error {
// You can also use MustCompile if you are sure the regular expression
// is valid, it panics instead of returning an error
re, err := regexp.Compile(`^\s+\/\s+`)
if err != nil {
return err // Handle error
}
if !regexp.MatchString(flag1) {
return fmt.Errorf("invalid value: %q", flag1)
}
fmt.Printf("Flag1 is %s\n", flag1)
return nil
},
}
Ho do you test command line arguments?
I can do this:
func TestMainFunc(t *testing.T) {
_, filename, _, _ := runtime.Caller(0)
dir := filepath.Dir(filename)
os.Args[1] = dir
main()
}
But then I override "test.v" in an argument list of:
os.Args[0]={string} "/private/var/folder/.../___appname.go"
os.Args[1]={string} "test.v"
os.Args[2]={string} "-test.panicontext0"
os.Args[3]={string} "^QTestMainFunc\E$"
I have no idea what these arguments are doing, but I suspect it is not good to override any of them - so how can you test arguments?
To expand upon Adrian's comment a bit, I would separate flag parsing from configuration entirely. Here's an example:
type Config struct {
verbose bool
greeting string
level int
}
func parseArgs(progname string, args []string) (config *Config, output string, err error) {
flags := flag.NewFlagSet(progname, flag.ContinueOnError)
var buf bytes.Buffer
flags.SetOutput(&buf)
var conf Config
flags.BoolVar(&conf.verbose, "verbose", false, "set verbosity")
flags.StringVar(&conf.greeting, "greeting", "", "set greeting")
flags.IntVar(&conf.level, "level", 0, "set level")
err = flags.Parse(args)
if err != nil {
return nil, buf.String(), err
}
return &conf, "", nil
}
The parseArgs function parses your program's configuration from command-line arguments, and is easily testable in isolation from the rest of the program.
So the flow in main would be:
func main() {
conf, output, err := parseArgs(os.Args[0], os.Args[1:])
if err != nil {
// ...
}
realMain(conf)
}
And now you can test parseArgs and realMain completely separately in unit tests.
This also opens up the possibility to have multiple sources for configuration: e.g. you could also read it from env vars or config files, or command-line. Multiple readers could populate a Config struct, and all would be testable in isolation.
Here is an snippet from my-tool/cmd/root.go
func Execute() {
if err := rootCmd.Execute(); err != nil {
fmt.Println(err)
os.Exit(1)
}
}
func init() {
cobra.OnInitialize(initConfig)
// Here you will define your flags and configuration settings.
// Cobra supports persistent flags, which, if defined here,
// will be global for your application.
rootCmd.PersistentFlags().StringVar(&cfgFile, "config", "", "config file (default is $HOME/.my-tool.yaml)")
// Cobra also supports local flags, which will only run
// when this action is called directly.
rootCmd.Flags().BoolP("toggle", "t", false, "Help message for toggle")
}
// initConfig reads in config file and ENV variables if set.
func initConfig() {
if cfgFile != "" {
fmt.Println("Config file set")
// Use config file from the flag.
viper.SetConfigFile(cfgFile)
} else {
fmt.Println("Config file NOT set")
// Find home directory.
home, err := homedir.Dir()
if err != nil {
fmt.Println(err)
os.Exit(1)
}
The code has been generated from the scaffolding process of cobra cli, i.e. via ~/go/cobra/init my-tool --pkg-name github.com/something/my-tool
I am trying to tentatively pass the config flag to check if the program is handling it:
▶ go run main.go --config "test"
However, though I 'd expect the init() function to make the call to cobra.OnInitialize(initConfig) and parse the flag as indicated by line:
rootCmd.PersistentFlags().StringVar(&cfgFile, "config", "", "config file (default is $HOME/.my-tool.yaml)")
and finally to see one of those two messages in the if statement:
func initConfig() {
if cfgFile != "" {
fmt.Println("Config file set")
// Use config file from the flag.
viper.SetConfigFile(cfgFile)
} else {
fmt.Println("Config file NOT set")
// Find home directory.
home, err := homedir.Dir()
if err != nil {
fmt.Println(err)
os.Exit(1)
}
instead, all I get is the root command's help message; why is that?
edit: from what I see by adding some print statements, the initConfig() is never called (for some reason), i.e. as if cobra.OnInitialize(initConfig) does not do anything.
You need to Specify your command first
▶ go run main.go "yourcommand" --config "test"
See:
» go run main.go --config "blah"
A longer description that spans multiple lines and likely contains
examples and usage of using your application. For example:
...
» go run main.go preview --config "blah"
Error: open : no such file or directory
exit status 1
The documentation in Cobra and Viper are confusing me. I did cobra init fooproject and then inside the project dir I did cobra add bar. I have a PersistentFlag that is named foo and here is the init function from the root command.
func Execute() {
if err := RootCmd.Execute(); err != nil {
fmt.Println(err)
os.Exit(-1)
}
fmt.Println(cfgFile)
fmt.Println("fooString is: ", fooString)
}
func init() {
cobra.OnInitialize(initConfig)
// Here you will define your flags and configuration settings.
// Cobra supports Persistent Flags, which, if defined here,
// will be global for your application.
RootCmd.PersistentFlags().StringVar(&cfgFile, "config", "", "config file (default is $HOME/.fooproject.yaml)")
RootCmd.PersistentFlags().StringVar(&fooString, "foo", "", "loaded from config")
viper.BindPFlag("foo", RootCmd.PersistentFlags().Lookup("foo"))
// Cobra also supports local flags, which will only run
// when this action is called directly.
RootCmd.Flags().BoolP("toggle", "t", false, "Help message for toggle")
}
My configuration file looks like this...
---
foo: aFooString
And when I call go run main.go I see this...
A longer description that spans multiple lines and likely contains
examples and usage of using your application. For example:
Cobra is a CLI library for Go that empowers applications.
This application is a tool to generate the needed files
to quickly create a Cobra application.
Usage:
fooproject [command]
Available Commands:
bar A brief description of your command
help Help about any command
Flags:
--config string config file (default is $HOME/.fooproject.yaml)
--foo string loaded from config
-h, --help help for fooproject
-t, --toggle Help message for toggle
Use "fooproject [command] --help" for more information about a command.
fooString is:
When I call go run main.go bar I see this...
Using config file: my/gopath/github.com/user/fooproject/.fooproject.yaml
bar called
fooString is:
So it is using the configuration file, but neither one of them seems to be reading it. Maybe I am misunderstanding the way that Cobra and Viper work. Any ideas?
To combine spf13/cobra and spf13/viper, first define the flag with Cobra:
RootCmd.PersistentFlags().StringP("foo", "", "loaded from config")
Bind it with Viper:
viper.BindPFlag("foo", RootCmd.PersistentFlags().Lookup("foo"))
And get the variable via the Viper's method:
fmt.Println("fooString is: ", viper.GetString("foo"))
Since Viper values are somewhat inferior to pflags (e.g. no support for custom data types), I was not satisfied with answer "use Viper to retrieve values", and ended up writing small helper type to put values back in pflags.
type viperPFlagBinding struct {
configName string
flagValue pflag.Value
}
type viperPFlagHelper struct {
bindings []viperPFlagBinding
}
func (vch *viperPFlagHelper) BindPFlag(configName string, flag *pflag.Flag) (err error) {
err = viper.BindPFlag(configName, flag)
if err == nil {
vch.bindings = append(vch.bindings, viperPFlagBinding{configName, flag.Value})
}
return
}
func (vch *viperPFlagHelper) setPFlagsFromViper() {
for _, v := range vch.bindings {
v.flagValue.Set(viper.GetString(v.configName))
}
}
func main() {
var rootCmd = &cobra.Command{}
var viperPFlagHelper viperPFlagHelper
rootCmd.PersistentFlags().StringVar(&config.Password, "password", "", "API server password (remote HTTPS mode only)")
viperPFlagHelper.BindPFlag("password", rootCmd.Flag("password"))
rootCmd.PersistentPreRunE = func(cmd *cobra.Command, args []string) error {
err := viper.ReadInConfig()
if err != nil {
if _, ok := err.(viper.ConfigFileNotFoundError); !ok {
return err
}
}
viperPFlagHelper.setPFlagsFromViper()
return nil
}
}
For those facing the same issue, the problem is on this call:
cobra.OnInitialize(initConfig)
The function initConfig is not executed directly but append to an array of initializers https://github.com/spf13/cobra/blob/master/cobra.go#L80
So, the values stored in your config file will be loaded when the Run field is executed:
rootCmd = &cobra.Command{
Use: "example",
Short: "example cmd",
Run: func(cmd *cobra.Command, args []string) { // OnInitialize is called first
fmt.Println(viper.AllKeys())
},
}
#WGH 's answer is correct, you can do something with the persistent flag in rootCmd.PersistenPreRun, which will be available in all other sub commands.
var rootCmd = &cobra.Command{
PersistentPreRun: func(_ *cobra.Command, _ []string) {
if persistentflag {
// do something with persistentflag
}
},