Node JS Environment Variables — Setting Node app for multiple environments.

Environment variables are one of the most important and core concepts of Nodejs as they allow us to configure our application for multiple environments and allow the application to behave differently for each environment such as development, test, stage, production. It is commonly used to configure ports, DB connection, host that our app should connect to for different environments modes or can be used in any part of the code that you think should change based on which environment mode you are running you application on. Configuring environment variables to a separate file rather than in our node js code enables us to run and point our app to different environments without rebuilding or making changes to our code.

In this Blog we will see how we can setup custom .env files for our node app for different environments using dotenv library

Getting Started

Let’s start with creating a node app first

Setting up our node app ⚙

To create a node app start with npm init command to create package.json file

npm init

Install Express.js with express package

npm express --save

Using dotenv package for Setting our node app for multiple environments

Let’s first start by installing dotenv package in our application by using below command

npm i dotenv --save

Now that we are done with installing all the libraries we need for our app, let’s jump on to creating our node app and configure our app for multiple environments usinf dotenv library.

Steps to setting up node app for multiple environments:

1️⃣ Create two .env files development.env and production.env

2️⃣ Create a config file to read and set the environment from .env files we created in first step

3️⃣ Create a server.js file as a startup file for our nodeapp

4️⃣ Set npm run scripts for multiple environments in package.json.

🔸 Creating .env files

Let’s create 2 new files development.env and production.env, one for each environment, which will have the NODE_ENV variable, host and port on which we want our application to run:



🔸 Create config file

The config file will use dotenv library that will allow us to load the desired .env file through the config() method and the path object.Once we read the file we will set the variable to the values of .env file and export them to use them further in server.js file

🔸 Creating a server.js file

Now that we have our different .env and config ready, we will now create the starting point of our app in server.js file, server.js file will import the config.js file and run our app basedon this config.

🔸 Set npm run commands:

We will modify package.json file to add two new tasks, for each environment, here we will set NODE_ENV that we want our application to run and specify the startup file for our app i.e server.js

Now let us run our app in two different modes (development and production) and see how our app picks up configurations that we setup for these modes.

To run the app in development mode use the command:

npm run dev

What happens here ? : when we run the command npm run dev, NODE_ENV is set to development frompackage .json script section, in config.js file, dotenv.config function reads the development.env file and set the environment variables as specified in the development.env file, server.js file read these set values from config.js file and executes the program accordingly

You will see that our app picks the configuration that we set up in development.env file i.e PORT : 3000 and HOST : localhost

app running in development mode

To run the app in production mode run the command

npm run prod

You will see that our app picks the configuration that we set up in production.env file i.e PORT: 8000 and HOST :

app running in production mode


Configuring different environments modes for our node app enables us to specify different config for each mode and allow us to run our application without the need to rebuild our app or make changes in our code.

Source: Medium