Can Viper work without a config file?

[rakshitgondwal]

Hey! I had this one question that can Viper work without a config file? If yes, how does viper manage the configuration in that case? Where does it write or read the values from?

[onlinejudge95]

Did you find any solution to this?
I am looking for a use case where the env vars are not loaded from .env file, typical case in container deployments, whereas viper reading the env vars and storing it in config struct like pydantic

[rakshitgondwal]

Not yet.

[onlinejudge95]

I found one solution where you can let go of reading from any config file and instead read from env vars, but the current implementation of viper would force you to bind all your envs 1st, I was expecting viper to register all the vars from os.Environ() implicitly.

Maybe try something like

package main

import (
    "fmt"
    "log"

    "github.com/spf13/viper"
)

type (
    Config struct {
        Name string `mapstructure:"NAME"`
        Host string `mapstructure:"HOST"`
    }
)

func main() {
    viper.SetEnvPrefix("APP")
    viper.AutomaticEnv()
    viper.BindEnv("NAME")
    viper.BindEnv("HOST")
    config := Config{}
    fmt.Println(viper.AllSettings())
    if err := viper.Unmarshal(&config); err != nil {
        log.Fatalln(err)
    }
    fmt.Printf("%#v\n", config)
}