godenv

README

godenv — a proper package to read .env files

The Twelve-Factor App Manifest promotes using environment variables as the only configuration approach. We follow and love this principle.

The .env files are just a genuine extension of env vars. The .env files simplify local debug, exposing variables to a Docker containers, and so on.

Godenv is a tiny package that reads those .env files.

Motivation

We took inspiration from the godotenv repository. The goal we pursued was to write a parser without using regular expressions but with a lexer/parser approach.

If you are curious about learning more about the approach, see the following links:

• https://en.wikipedia.org/wiki/Abstract_syntax_tree
• https://en.wikipedia.org/wiki/Lexical_analysis
• https://en.wikipedia.org/wiki/Parsing#Parser

Installation

go get github.com/youla-dev/godenv

Usage

Add a configuration to your .env file:

HTTP_ADDRESS=":8080"
LOG_LEVEL="info"

Then in the Go app read the file and parse its content:

package main

import (
	"fmt"
	"os"

	"github.com/youla-dev/godenv"
)

func main() {
	f, err := os.Open(".env")
	if err != nil {
		panic(err)
	}
	defer f.Close()

	vars, err := godenv.Parse(f)
	if err != nil {
		panic(err)
	}

	fmt.Println(vars)
}

Pronunciation

godenv stands for go-dot-env. It is pronounced as goh denv, not as gahd env.

Specification

The complete specification can be found here: SPECIFICATION.md.

Documentation

Overview

Package godenv is a tiny module that parses .env files.

Motivation

We took inspiration from the godotenv (https://github.com/joho/godotenv) repository. The goal we pursued was to write a parser without using regular expressions but with a lexer/parser approach.

The current specification of .env files format is listed in SPECIFICATION.md (https://github.com/youla-dev/godenv/blob/main/SPECIFICATION.md).

If you are curious about learning more about the approach, see the following links:

• https://en.wikipedia.org/wiki/Abstract_syntax_tree
• https://en.wikipedia.org/wiki/Lexical_analysis
• https://en.wikipedia.org/wiki/Parsing#Parser

Usage

Let's assume, you have a .env file with the following content:

HTTP_LISTEN=":8080"
LOG_LEVEL="info"

You can easily open the file and parse its content into map[string]string:

f, err := os.Open(".env")
if err != nil {
	panic(err)
}
defer f.Close()

vars, err := godenv.Parse(f)
if err != nil {
	panic(err)
}
fmt.Println(vars)

Index

• func Parse(r io.Reader) (map[string]string, error)

Examples

• Parse

Functions

func Parse

func Parse(r io.Reader) (map[string]string, error)

Parse reads an env file from io.Reader, returning a map of keys and values.

Example

package main

import (
	"bytes"
	"fmt"

	"github.com/youla-dev/godenv"
)

func main() {
	envContent := `VARIABLE_1='This is variable 1'
# This is comment
VARIABLE_2="This is variable 2"
VARIABLE_TAB_1='Tab is not escaped\t'
VARIABLE_TAB_2="Tab is escaped\t"`

	buf := bytes.NewBufferString(envContent)

	result, err := godenv.Parse(buf)
	if err != nil {
		panic(err)
	}
	fmt.Println(result)
}

Output:

map[VARIABLE_1:This is variable 1 VARIABLE_2:This is variable 2 VARIABLE_TAB_1:Tab is not escaped\t VARIABLE_TAB_2:Tab is escaped	]