Nginx Rewrite Proxy_Pass

Nginx is an open-source web server used widely for serving static assets, load balancing, or as a reverse proxy. One of the popular features of Nginx is its ability to handle URL rewriting as well as forwarding requests to backend servers using the proxy_pass directive. In this article, we will cover how to use Nginx's rewrite and proxy_pass directives to forward requests to a backend server.

Prerequisites

Before you begin, you need to have a server with Nginx installed and a backend server that you want to forward requests to.

Step 1: Setting up the Nginx server block

First, we need to create an Nginx server block that will handle incoming requests and forward them to the backend server. Here’s an example of a server block that listens on port 80 and forwards requests to a backend server running on port 3000:

server {
    listen 80;
    server_name example.com;
    location / {
        rewrite ^/api/(.*)$ /$1 break;
        proxy_pass http://localhost:3000/;
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    }
}

In this example, we are using the server_name directive to specify the domain name that the server block will handle. The listen directive defines the port the server will listen on for incoming requests.

The location directive defines the URL path where requests will be forwarded to the backend server. In this case, we are using the rewrite directive (rewrite ^/api/(.*)$ /$1 break;) to strip the /api path from the incoming requests.

The proxy_pass directive is used to forward the requests to the backend server. We are using the localhost:3000 as the backend server address.

Finally, we are using the proxy_set_header directive to set the Host, X-Real-IP, and X-Forwarded-For headers to pass to the backend.

Step 2: Testing the configuration

After setting up the server block, we need to test if it is working correctly. We can use the curl command to send a request to the Nginx server. Assuming you are running the Nginx server on your local machine, run the following command:

curl http://localhost/api/data

This command sends a GET request with the path /api/data to the Nginx server. The server should forward the request to the backend server running on port 3000, and return the response.

If everything is set up correctly, you should be able to see the response from the backend server in your terminal.

Step 3: Troubleshooting

If you encounter any issues, you can check the Nginx error log for more information. The error log is typically located at /var/log/nginx/error.log.

You can also run Nginx in debug mode by adding the -g 'daemon off;' option to the command that starts Nginx. This will prevent Nginx from running as a daemon and will output debug messages to the terminal.

Conclusion

In conclusion, Nginx's rewrite and proxy_pass directives are powerful tools for forwarding requests to a backend server. By using these directives, you can easily set up a reverse proxy to handle incoming requests and forward them to the appropriate backend server based on their URL paths.