How to Configure Nginx as a Reverse Proxy on Ubuntu: 4 Easy Steps

In today’s digital landscape, exposing application servers directly to the internet can be risky. Whether you’re running a Node.js app, a Flask server, or any other backend service, it’s often safer to hide these servers behind a reverse proxy.

A reverse proxy acts as an intermediary between clients and your application server, providing an additional layer of security, load balancing, and performance optimization. One of the most popular tools for this purpose is Nginx, a high-performance web server and reverse proxy solution.

In this article, we’ll dive deep into how to configure Nginx as a reverse proxy. By the end, you’ll have a clear understanding of the steps involved, the benefits of using a reverse proxy, and how to set it up for your own applications. Whether you’re a beginner or an experienced developer, this guide will walk you through the process in an easy-to-understand manner.

Why Use Nginx as a Reverse Proxy?

Before we get into the technical details, let’s explore why you might want to configure Nginx as a reverse proxy:

1. Enhanced Security: By placing your application server behind Nginx, you isolate it from direct internet access. This reduces the attack surface and protects against common threats like DDoS attacks.
2. Load Balancing: Nginx can distribute incoming traffic across multiple application servers, ensuring optimal performance and high availability.
3. SSL/TLS Termination: Nginx can handle SSL/TLS encryption, offloading this resource-intensive task from your application server.
4. Caching: Nginx can cache static content, reducing the load on your application server and improving response times.
5. Simplified Client Interaction: From the client’s perspective, interacting with a reverse proxy is no different from interacting directly with the application server. This seamless experience requires no additional configuration on the client side.

Now that we understand the benefits, let’s move on to the practical steps of how to configure Nginx as a reverse proxy.

Prerequisites

Before we begin, ensure you have the following:

1. A Server: This tutorial assumes you’re using an Ubuntu 22.04 server. If you’re using a different operating system, the steps may vary slightly.
2. An Application Server: This is the server you want to proxy. It could be a Node.js app, a Flask server, or any other backend service. For testing purposes, we’ll use a simple Gunicorn server.
3. A Domain Name: Point your domain to your server’s public IP address. This will allow you to access your application through the reverse proxy.

How to Configure Nginx as a Reverse Proxy: Step-by-Step

Step 1: Installing Nginx

The first step in how to configure Nginx as a reverse proxy is to install Nginx on your server. Nginx is available in Ubuntu’s default repositories, so the installation process is straightforward.

Update your package repository index:

sudo apt update

Install Nginx:

sudo apt install nginx

Press Y to confirm the installation.

Allow Nginx through your firewall:

sudo ufw allow 'Nginx HTTP'

Verify that Nginx is running:

systemctl status nginx

You should see an output indicating that Nginx is active and running.

Output
● nginx.service - A high performance web server and a reverse proxy server
     Loaded: loaded (/lib/systemd/system/nginx.service; enabled; vendor preset: enabled)
     Active: active (running) since Mon 2022-08-29 06:52:46 UTC; 39min ago
       Docs: man:nginx(8)
   Main PID: 9919 (nginx)
      Tasks: 2 (limit: 2327)
     Memory: 2.9M
        CPU: 50ms
     CGroup: /system.slice/nginx.service
             ├─9919 "nginx: master process /usr/sbin/nginx -g daemon on; master_process on;"
             └─9920 "nginx: worker process

Step 2: Configuring Nginx as a Reverse Proxy

Now that Nginx is installed, it’s time to configure it as a reverse proxy. This involves creating a custom server block and specifying the proxy_pass directive.

Create a new configuration file for your domain:

sudo nano /etc/nginx/sites-available/example.com

Add the following configuration to the file:

server {
     listen 80;
     listen [::]:80;

     server_name example.com www.example.com;

     location / {
         proxy_pass http://127.0.0.1:8000;  # Replace with your app server address
         include proxy_params;
     }
 }

• Replace example.com with your actual domain name.
• Replace http://127.0.0.1:8000 with the address of your application server.

Save and close the file.

Enable the configuration by creating a symbolic link to the sites-enabled directory:

sudo ln -s /etc/nginx/sites-available/example.com /etc/nginx/sites-enabled/

Test the Nginx configuration for syntax errors:

sudo nginx -t

If everything is correct, you’ll see a message indicating that the syntax is OK.

Restart Nginx to apply the changes:

sudo systemctl restart nginx

At this point, Nginx is configured as a reverse proxy for your application server. If your application server is running, you should be able to access it by navigating to your domain in a web browser.

Step 3: Understanding the proxy_params File

When configuring Nginx as a reverse proxy, it’s important to forward the appropriate headers from the client’s request. This ensures that your application server receives all the necessary information about the client.

The proxy_params file, included in the Nginx configuration, contains recommended settings for header forwarding. Here’s what it typically includes:

proxy_set_header Host $http_host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header X-Forwarded-Proto $scheme;

• Host: Passes the original host requested by the client.
• X-Real-IP: Passes the client’s IP address.
• X-Forwarded-For: Passes a list of IP addresses, including the client’s IP and any intermediate proxies.
• X-Forwarded-Proto: Passes the protocol (HTTP or HTTPS) used by the client.

These headers ensure that your application server has access to the client’s original request information, which is crucial for logging, authentication, and other functionalities.

Step 4: Testing Nginx as a Reverse Proxy with Gunicorn (Optional)

If you don’t have an application server to test with, you can set up a simple Gunicorn server to verify your Nginx reverse proxy configuration.

example.com

However, if you don’t have an application server available to test your reverse proxy, follow these steps to install Gunicorn along with a simple test application. Gunicorn is a Python WSGI server commonly used alongside an Nginx reverse proxy.

Install Gunicorn:

First, update your package list and install Gunicorn using:

sudo apt update
sudo apt install gunicorn

Alternatively, you can install the latest version of Gunicorn using pip from PyPI, especially if you’re working within a Python virtual environment. However, for this guide, apt is used for a quick setup.

Create a simple Python application:

Now, you’ll write a basic Python function that returns “Hello World!” as an HTTP response. Open a new file named test.py using nano or any text editor of your choice:

nano test.py

Add the following code:

def app(environ, start_response):
    start_response("200 OK", [])
    return iter([b"Hello, World!"])

To initiate an HTTP response with Gunicorn that displays a text string in your web browser, this is the essential code you need. Once you’ve reviewed it, be sure to save and close the file.

Next, launch your Gunicorn server by defining the test Python module along with the app function. Once the server starts, it will occupy your terminal session.

gunicorn --workers=2 test:app

This will start the server at http://127.0.0.1:8000.

Output
[2025-02-18 07:09:29 +0000] [10568] [INFO] Starting gunicorn 20.1.0
[2025-02-18 07:09:29 +0000] [10568] [INFO] Listening at: http://127.0.0.1:8000 (10568)
[2025-02-18 07:09:29 +0000] [10568] [INFO] Using worker: sync
[2025-02-18 07:09:29 +0000] [10569] [INFO] Booting worker with pid: 10569
[2025-02-18 07:09:29 +0000] [10570] [INFO] Booting worker with pid: 10570

The output confirms that Gunicorn is successfully running and listening at the default address http://127.0.0.1:8000. This is the same address you specified earlier in your Nginx configuration file under the proxy_pass directive. If Gunicorn is listening on a different address or port, you’ll need to revisit your Nginx configuration file located at /etc/nginx/sites-available/example.com and update the app_server_address in the proxy_pass directive to match the correct address.

Once everything is properly configured, open your web browser and navigate to the domain you set up with Nginx (e.g., http://example.com). If the setup is correct, you should see your application’s response, such as “Hello, World!”, displayed in the browser. This confirms that Nginx is successfully acting as a reverse proxy, forwarding requests to your Gunicorn application server.

Open your web browser and navigate to your domain. You should see the message “Hello, World!” displayed, confirming that Nginx is successfully proxying requests to your Gunicorn server.

Conclusion

Configuring Nginx as a reverse proxy is a powerful way to enhance the security, performance, and scalability of your application servers. By following this guide, you’ve learned how to configure Nginx as a reverse proxy, from installation to setting up custom server blocks and forwarding headers.

Whether you’re running a small personal project or a large-scale production application, using Nginx as a reverse proxy is a best practice that can significantly improve your server’s reliability and security. With this knowledge, you’re now equipped to set up and manage reverse proxies for your own applications.

For further reading, consider exploring advanced topics like load balancing, SSL/TLS configuration, and caching with Nginx. These features can take your reverse proxy setup to the next level, ensuring your applications are fast, secure, and highly available.

Happy proxying!