Settings Example

.env

DATABASE_TABLE=example
DATABASE_DSN=example:[email protected]/example
DATABASE_DRIVER=mysql

PING_LOCATIONS=one,two,three

main.go

package main

import "settings"

func main() {
  // While the config struct is in the settings package, it doesn't have to be.
  conf, err := settings.Load[settings.App]()
  // ...
}

settings.go

package settings

import (
	"os"

	"github.com/joho/godotenv"
	"github.com/kelseyhightower/envconfig"
)

// App holds onto the application specific configurations.
type App struct {
	Database Database
	Ping     Ping
}

// Database holds onto the Database specific configurations.
type Database struct {
	Table  string
	DSN    string // CBA to break down the dumb fields.
	Driver string // used for testing, mostly.
}

// Ping holds onto the Ping specific configurations.
type Ping struct {
	Locations []string
}

// Load loads the settings.
func Load[T any]() (T, error) {
	var conf T

	if err := godotenv.Load(); err != nil {
		// We don't care if an .env is missing, it won't exist in prod.
		if !os.IsNotExist(err) {
			return conf, err
		}
	}

	if err := envconfig.Process("", &conf); err != nil {
		return conf, err
	}

	return conf, nil
}