Go Vars

This is a Go library for simple configuration management. It act as a key-value store backed with default value. Each value can be override with environment variable. This library utilize generics in Go 1.18.

Usage

package main

import (
	"errors"
	"io/fs"
	"log"

	"github.com/joho/godotenv"
	"github.com/ultimicro/vars"
)

const (
	KeyFoo vars.Key[int]    = "Foo"
	KeyBar vars.Key[string] = "Bar"
)

func main() {
	vars.SetDefault(KeyFoo, 7)
	vars.SetDefault(KeyBar, "abc")

	// When lookup for environment variable the specified key will transform to
	// snake case in upper case (e.g. MYAPP_KEY1) by default. Use
	// SetEnvKeyTransformer() to change this behavior.
	vars.SetEnvPrefix("MYAPP_")

	// Remove the following code if you don't want to load .env file.
	if err := godotenv.Load(); err != nil {
		if !errors.Is(err, fs.ErrNotExist) {
			log.Fatalln(err)
		}
	}

	// Now you can access your configuration with vars.Get(Key).
}

Override environment variable name

You can override environment variable name for a specific key by using SetEnvName:

vars.SetEnvName(Key, "SOmeWeIrDNaME")

This name will not get transformed by KeyTransformer but the prefix that was specified by SetEnvPrefix still in effect.

Custom parser

If you need to change how the value is parsed you can set an implementation of ValueParser to use with SetParser:

vars.SetParser[SomeType](Key, &SomeTypeParser{})

Yes you need to specify type manually due to currently Go cannot infer type in this case.

License

MIT