How to Use envconfig for Struct-Based Configuration in Go

You use envconfig by defining a struct with struct tags that map environment variables to fields, then calling envconfig.Process to populate it. The library reads the environment, parses values, and assigns them to the struct fields based on the env tag key.

package main

import (
	"github.com/kelseyhightower/envconfig"
)

type Config struct {
	DatabaseHost string `env:"DATABASE_HOST"`
	DatabasePort int    `env:"DATABASE_PORT"`
	Debug        bool   `env:"DEBUG"`
}

func main() {
	var config Config
	if err := envconfig.Process("", &config); err != nil {
		panic(err)
	}
	// Use config.DatabaseHost, etc.
}

Set the environment variables before running your program:

export DATABASE_HOST=localhost
export DATABASE_PORT=5432
export DEBUG=true

The envconfig.Process function reads these variables and fills the Config struct. If a variable is missing and no default is set, the field remains at its zero value.

envconfig lets you load your application settings from environment variables directly into a Go struct. Instead of manually reading each variable and converting types, you just define a struct with tags, and the library handles the rest. It's like filling out a form where the environment variables are the answers.