Viper: Get config values from environment variables

[r0l1]

It is common to use environment variables in container systems as docker to configure settings. It would be great if viper would handle this too:

Defaults -> Environment Variables -> Settings Files -> Command Options

[yesnault]

It's already possible, with https://github.com/spf13/cobra / https://github.com/spf13/pflag and viper, something like that :

viper.AutomaticEnv()
flags := rootCmd.Flags()
flags.StringVarP(&username, "username", "u", "", "username, facultative if you have config file")
viper.BindPFlag("username", flags.Lookup("username"))

[r0l1]

Perfect, thank you!

[rogierlommers]

Working fine, I like!

[four2five]

Does it make sense to close this issue if the indicated functionality is present (and therefore not an issue) ?

[scotthew1]

does anyone have a full working example of this env binding? i've seen @yesnault's snippit in a few different places, but i'm not actually getting the var i care about populated with the env. am i missing something here?

package main

import (
    "fmt"

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

func main() {
    var thing1 string
    var thing2 string

    var cmd = &cobra.Command{
        Use:   "viper-test",
        Short: "testing viper",
        Run: func(command *cobra.Command, args []string) {
            fmt.Printf("thing1: %q\n", thing1)
            fmt.Printf("thing2: %q\n", thing2)
        },
    }

    viper.AutomaticEnv()
    flags := cmd.Flags()
    flags.StringVar(&thing1, "thing1", "", "The first thing")
    viper.BindPFlag("thing1", flags.Lookup("thing1"))
    flags.StringVar(&thing2, "thing2", "", "The second thing")
    viper.BindPFlag("thing2", flags.Lookup("thing2"))

    cmd.Execute()
}

$ export THING1=hello THING2=world

$ ./viper-test
thing1: ""
thing2: ""

$ ./viper-test --thing1 hello --thing2 world
thing1: "hello"
thing2: "world"

[yesnault]

@scotthew1

package main

import (
    "fmt"

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

func main() {
    var cmd = &cobra.Command{
        Use:   "viper-test",
        Short: "testing viper",
        Run: func(command *cobra.Command, args []string) {
            fmt.Printf("thing1: %q\n", viper.GetString("thing1"))
            fmt.Printf("thing2: %q\n", viper.GetString("thing2"))
        },
    }

    viper.AutomaticEnv()
    flags := cmd.Flags()
    flags.String("thing1", "", "The first thing")
    viper.BindPFlag("thing1", flags.Lookup("thing1"))
    flags.String("thing2", "", "The second thing")
    viper.BindPFlag("thing2", flags.Lookup("thing2"))

    cmd.Execute()
}

[scotthew1]

@yesnault yeah i was able to get something like that working, but i was hoping viper would work with the *Var() flags.. your example from before uses StringVarP() and the example from the cobra readme shows the same. i was ultimately hoping to have a config struct that viper/pflags would populate that my code could use without having to cal viper.Get(). is this not possible as the examples imply?

[scotthew1]

ah... i just read past further past the example i linked...

Note, that the variable author will not be set to the value from config, when the --author flag is not provided by user.

that makes for a pretty unfortunate example... any ideas for doing what i described in my previous comment? or am i misunderstanding viper's utility?

[danielmai]

Is there any updates on @scotthew1's question? Using the options like StringVar or StringVarP and having the config value be populated into the var would be ideal. There shouldn't be a need to call Viper.Get() in order to get the value from the CLI options, config file, environment variables, etc.

[McShauno]

I truly don't understand the usefulness of the viper integration if I still have to call Viper.get() instead of it automatically being bound to the variable. Is there any movement on this?

[sagikazarmark]

You don't have to call Get. You can unmarshal values into a struct from Viper.

*Var will never work though, because pflag is integrated into Viper, not the other way around. pflag is used as a source, values never travel from viper to pflag and *Var is a pflag feature.

[sagikazarmark]

Closing as this feature is already implemented. Please open separate discussions.