Running Multiple Node Express Apps On Same Port

When developing with Node.js and Express, you might come across the need to run multiple applications on the same port locally. While this can sound daunting at first, fear not! With a few tricks up your sleeve, you can accomplish this task seamlessly.

Firstly, let's discuss why you may want to host multiple Node Express applications on the same port. It's a great way to simplify local development and testing, especially when working on microservices or different parts of a larger project that need to communicate with each other.

To achieve this, you need to leverage a tool called 'http-proxy-middleware.' This package allows you to proxy requests to different Express applications based on specific rules. Installing it is easy - simply use npm or yarn:

npm install http-proxy-middleware

Once you have 'http-proxy-middleware' installed, you need to create a new JavaScript file to handle the routing. Let's call it 'proxy.js.' Here's a basic example of how you can set up routing for two Express applications (App1 and App2):

const express = require('express');
const { createProxyMiddleware } = require('http-proxy-middleware');

const app = express();

app.use('/app1', createProxyMiddleware({ target: 'http://localhost:3001', changeOrigin: true }));
app.use('/app2', createProxyMiddleware({ target: 'http://localhost:3002', changeOrigin: true }));

app.listen(3000, () => {
  console.log('Proxy server running on http://localhost:3000');
});

In this example, we create a new Express app, define routes for 'app1' and 'app2,' and use 'createProxyMiddleware' to redirect requests to the respective applications running on ports 3001 and 3002.

Now, you need to start your individual Express applications on their designated ports (3001 and 3002 in this case) before running the 'proxy.js' file on port 3000.

To run your proxy server, execute the following command in your terminal:

node proxy.js

Voila! You now have a single entry point running on port 3000 that forwards requests to your multiple Express applications running on different ports.

Remember, this setup is intended for development purposes. Make sure to adjust your production configuration accordingly for seamless deployment.

In conclusion, running multiple Node Express apps on the same port is a handy technique for local development. With the 'http-proxy-middleware' package and a bit of routing setup, you can streamline your workflow and test multiple applications simultaneously.

Happy coding!