Introduction to dotenv

The dotenv library 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 and can be very useful for managing application configurations.

Installation

npm install dotenv

Basic Usage

Create a file named .env in the root directory of your project and add your environment-specific variables on new lines:

  DB_HOST=localhost
  DB_USER=root
  DB_PASS=s1mpl3

In your main application file, require and configure dotenv:

require('dotenv').config();

After this, you can access the variables defined in your .env file via process.env:

  console.log(process.env.DB_HOST); // localhost
  console.log(process.env.DB_USER); // root
  console.log(process.env.DB_PASS); // s1mpl3

Advanced Options

dotenv supports several advanced configurations:

Custom Path

  require('dotenv').config({ path: '/custom/path/to/.env' });

Silent Failures

  require('dotenv').config({ silent: true });

Example App

Here is a sample Node.js application that uses dotenv to configure a simple Express server:

  const express = require('express');
  require('dotenv').config();

  const app = express();
  const port = process.env.PORT || 3000;

  app.get('/', (req, res) => {
    res.send(`Database Host: ${process.env.DB_HOST}`);
  });

  app.listen(port, () => {
    console.log(`Server running on port ${port}`);
  });

Conclusion

The dotenv module is an excellent tool for managing configuration in Node.js applications, ensuring that sensitive information like database credentials does not get hard-coded into your source files. By separating your environment configurations, you make your applications more secure and easier to maintain.

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