How to Use Environment Variables in Node.js?

English

Apr 26, 2018

Table of contents

Working with Environment Variables is IMPORTANT in Software Development. Every stage, such as Development, Testing or Production, uses its environment variables. It also secures the Privacy for Production on clouds such as Heroku, AWS, Azure,… How do we do that in NodeJS?

Introduction

As I mentioned above, suppose that we need to connect to a database, we maybe have a username and a password for connection. However, each environment our team use is different. Everyone in our team uses localhost with own username and password. Password and Private Key are IMPORTANT and PRIVACY on production, which only someone has and use it on cloud or server. Therefore environment variables is neccessary when our team developes an application.

In this tutorial, I’ll introduce you how we can use environment variables in Node.js Application.

What is `dotenv`?

dotenv - Loads environment variables from .env for nodejs projects.

Dotenv is a zero-dependency module that loads environment variables from a .env file into process.env. Storing configuration in the environment separate from code is based on The Twelve-Factor App methodology.

In Node.js Application, we’ll use package dotenv to connect environment variables.s

How to Use `dotenv` in Node.js?

Create simple Node.js project

Create directory node-env

mkdir node-env

Use npm init to create simple Node.js with file package.json

npm init

package.json will be such as:

{
    "name": "@sam/node-env",
    "version": "1.0.0",
    "description": "",
    "main": "index.js",
    "scripts": {
        "test": "echo \"Error: no test specified\" && exit 1"
    },
    "author": "",
    "license": "ISC"
}

Create file index.js:

touch index.js

Edit file index.js with:

console.log('Hello Node.js');

In package.json, add start script which run file index.js:

{
    "name": "@sam/node-env",
    "version": "1.0.0",
    "description": "",
    "main": "index.js",
    "scripts": {
        "start": "node index",
        "test": "echo \"Error: no test specified\" && exit 1"
    },
    "author": "",
    "license": "ISC"
}

Start file index.js by:

npm start

You will see on terminal

> node index
Hello Node.js

Install `dotenv` dependency

yarn add dotenv

# or use with npm
npm install dotenv --save

Config, Load and Read Environment Variables

In file index.js, at the top, require and config dotenv:

require('dotenv').config();

Create file .env and add some environment, dotenv will load them to process.env.*:

touch .env

In file .env add some variables:

USERNAME=huynhsamha
PASSWORD=kjry9bq34vj0394u0349ut02v33v5y

Edit file index.js:

require('dotenv').config();

console.log(process.env.USERNAME);
console.log(process.env.PASSWORD)

You will see on terminal:

> node index
huynhsamha
kjry9bq34vj0394u0349ut02v33v5y

Ignore file `.env`

If you use git for your project, file .env should not included in repository, in file .gitignore, add .env to ignore it.

.env

You should use the default file .gitignore for Node.js Application at https://github.com/github/gitignore/blob/master/Node.gitignore

Conclusion

I have shown you how to use environment variables in Node.js application with dotenv.

Thanks for reading my article! If you have any feedback or criticism, feel free to leave any comment!

Introduction

What is dotenv?

How to Use dotenv in Node.js?