How do I setup the dotenv file in Node.js?

Question

In my case, every time I tried to get a key from the .env file using process.env.MY_KEY, it returned undefined.

I suffered from this problem for two hours just because I named the file something like keys.env which is not considered to be a .env file.

So here is the troubleshooting list:

The filename should be .env (I believe .env.test is also acceptable).
Make sure you are requiring it as early as possible in your application using this statement require('dotenv').config();
The .env file should be in the root directory of your project.
Follow the “file writing rules” like DB_HOST=localhost, no need to wrap values in double/single quotes.

Also, check the documentation of the package on the NPM site.