Using NodeJS library `dotenv` to Handle Environmental Variables and Secret Keys — Tutorial

Overview

Today, I'm going to show you how use the JavaScript library called dotenv, which is used to access environment variables in a NodeJS project.\
Environment variables can hold secret keys such as API keys, login credentials, or any other number of information you need to use, but want to keep hidden from the users/internet.

We will:

1. Start an empty NodeJS project.
2. Create all necessary files for project.
3. Import the dotenv library.
4. Configure dotenv environmental variables.
5. Code a command using dotenv.
6. Code a more advanced command with opener.
7. Wrap up the project with some git essentials.

Follow along with this text tutorial, or watch the video going over all of this. Or check out the GitHub repository!

So let's start!

Getting Started

Create a folder for your project however you normally do. I am going to use the terminal, Bash:

• Navigate to wherever you'd like to save the demo and type:

mkdir demo-dotenv

• Just to make sure we have Node installed, type:

node -v

• If it doesn't tell you a version number, then you need to install node. Head over to https://nodejs.org/en/ and install the version for your OS and then come back.
• Let's also check if you have Git installed too, type:

git --version

• Same as before, if it doesn't tell you a version number, then you need to install git. Head over to https://git-scm.com/downloads and install the version for your OS and then come back.

Now we have a folder to work out of, and our set up out of the way. Let's open our IDE next. I use VSCodium, but you can use whatever you want.

• Inside your IDE, open our project folder that we made already.

Now we have a fresh slate to work with.

Create Project Files

Let's create some empty files in our new folder.\
Make them all in the top-level of the directory - meaning place them all in this folder without any other folders added for depth/nesting.

• Create a main.js file to run our code in.
• Create a .env file to keep our variables in.
• Create a .gitignore to follow best practices and avoid pushing unwanted files to GitHub.
• Create a .env-sample file to use as an example for the future.

Install dotenv Library Dependencies

Before we start installing libraries, let's get our package.json file.

• In the terminal, type:

npm init

Let's go to npm's dotenv page to find the package and get downloading and usage instructions.

• In the terminal, type:

npm i dotenv

This installs the library so we can use it in our project.

Config Dotenv

Now we need to import it properly.\
If you check the npm site, it says we need to add this near the top of main.js (always keep at the bottom of any other imports you might add to your own projects):

require('dotenv').config();

This is a bit different than most packages, and should always be kept at the bottom of your imports, and above any code you're calling an environment variable with.\
Great! Now we have our project ready to code!

Create "Hello World" Command

Let's start coding!

• Below the dotenv import, type:

console.log("Hello, " + process.env.name + "!");

This will give us a "Hello World"-type message when we run it correctly. But, first we need to assign our name to the environment variable name.

• Go to the .env file and add:

name="User"

• Save your project and we are ready to run it.

• In the terminal, type:
  

node main.js

It works! Cool!

Hello User!

Add opener and Create "Opener" Command

Now let's add something a bit more useful to give you a better idea of how to use environment variables.

Go to the npm opener website. opener is a library that allows us to automatically open a website in a new browser tab/window.

• Install opener in your project directory's terminal with:

npm i opener

• Let's import it to main.js now. At the top of the main.js (above the dotenv config) type:

const opener = require('opener');

• Then, at the bottom of your main.js file type:

opener(process.env.url);

This will call whatever URL we have at the .env variable url. But that variable doesn't exist yet, so let's go fix that!

• On a new line in .env, type:

url="https://nodejs.org/en/"

This will open the NodeJS website when we run our program. Let's test it out now.

• In the terminal run:

node main.js

Pretty cool, huh?

Preparing to Push to GitHub

One last thing to know is that .env (or node_modules/ because they take up too much unnecessary space) files should never be uploaded to Github or any other version control system. If you do, anyone can read your private environment variables!

To get around this, we need a .gitignore file. This is usually created for you as an option if you make a new project with GitHub, but we will do it from scratch.

• Previously, we created a .gitignore file. Open it, and inside add:

node_modules/
.env

This will now exclude your .env file and node_modules/ from ever being uploaded with git to a version control.
We will want to create a sample .env to show our potential users (or just remind ourselves in the future) what to do with their .env file if they are going to use our program themselves.

• In our .env-sample file, add:

name="your-name"
url="your-url"

This .env-sample will upload to version control because it isn't listed in our .gitignore file. It is merely there as a reference, and it has no sensitive information. This is crucial when using a private API key or secrets.

Check out the GitHub repository!
Well there you have it folks. dotenv in all of it's glory! Good luck and have fun! :)

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