Nginx as a reverse proxy

Intermediate 12 min read

Put a web server in front of your application to handle HTTPS, static files and forwarding.

Why it matters

Application servers are not built to face the internet directly. A reverse proxy terminates HTTPS, serves static files fast, and forwards the rest to your app — and it is where many deployment errors (502, 504) show up first.

Where it fits

What you will learn

Explain what a reverse proxy does.
Read a server block that forwards requests to an app.
Find the cause of a 502 Bad Gateway.

Before you start

HTTP and APIs✓ Learned
Containers with Docker✓ Learned

The request path

Browser
Nginx :443 (HTTPS)
App :3000
Database

A minimal server block

/etc/nginx/conf.d/app.conf

server {
    listen 80;
    server_name app.example.com;

    location / {
        proxy_pass http://127.0.0.1:3000;
        proxy_set_header Host $host;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Proto $scheme;
    }
}

In production add a listen 443 ssl block with a certificate; port 80 then only redirects to HTTPS.

Example

sudo nginx -t                # check the configuration
sudo systemctl reload nginx  # apply it without dropping connections

Tip: A 502 Bad Gateway almost always means Nginx is fine but the app behind it is not running, or listens on a different address or port. Check the app first, then the Nginx error log.

Install and set up

Nginx Linux packages ↗ Official packages for the common Linux distributions.

Official documentation and references

Documentation

Nginx documentation ↗ Official · nginx.org

Guides

Nginx beginner's guide ↗ Official · nginx.org

Reference

ngx_http_proxy_module ↗ Official · nginx.org — Every proxy_ directive explained.

Learn next

HTTPS and certificates ›✓ Learned

Done with this topic?

Reviewed 2026-10-23. Links go to the official documentation unless marked otherwise.