How to Set Up Nginx Reverse Proxy with SSL on Ubuntu 24.04 (Complete Blueprint)

What is a Reverse Proxy and Why is Nginx the Best Choice?

A reverse proxy sits between public client connections and private backend application servers (such as a Next.js frontend running on port 3000, an Express API on port 5000, or a FastAPI Python backend on port 8000). Nginx handles TLS certificate negotiation, HTTP/2 multiplexing, static asset caching, and request buffering, isolating your application runtime from direct Internet attacks.

Step 1: Installing Nginx on Ubuntu 24.04

sudo apt update
sudo apt install -y nginx

Step 2: Creating a Production Reverse Proxy Virtual Host

Create a dedicated virtual host configuration in /etc/nginx/sites-available/api.example.com:

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

Add the following production configuration with proxy buffering and WebSocket upgrades:

# Upstream pool pointing to local application backend
upstream backend_app {
    server 127.0.0.1:3000;
    keepalive 32;
}

server {
    listen 80;
    listen [::]:80;
    server_name api.example.com;

    # Redirect all plain HTTP traffic to secure HTTPS
    return 301 https://$host$request_uri;
}

server {
    listen 443 ssl http2;
    listen [::]:443 ssl http2;
    server_name api.example.com;

    # SSL Certificate Paths (provisioned by Certbot)
    ssl_certificate /etc/letsencrypt/live/api.example.com/fullchain.pem;
    ssl_certificate_key /etc/letsencrypt/live/api.example.com/privkey.pem;

    # Reverse Proxy Location Block
    location / {
        proxy_pass http://backend_app;
        proxy_http_version 1.1;

        # WebSocket support
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection "upgrade";

        # Forward authentic client IP and host headers
        proxy_set_header Host $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;

        # Timeouts and Buffer Sizes
        proxy_connect_timeout 60s;
        proxy_send_timeout 60s;
        proxy_read_timeout 60s;
        proxy_buffer_size 128k;
        proxy_buffers 4 256k;
        proxy_busy_buffers_size 256k;
    }
}

Step 3: Enabling Site and Validating Syntax

sudo ln -s /etc/nginx/sites-available/api.example.com /etc/nginx/sites-enabled/
sudo nginx -t
sudo systemctl reload nginx

Step 4: Tuning Gzip Compression & Rate Limiting

Enable gzip compression in /etc/nginx/nginx.conf to compress JSON payloads and CSS/JS assets on the fly:

gzip on;
gzip_vary on;
gzip_proxied any;
gzip_comp_level 6;
gzip_types text/plain text/css text/xml application/json application/javascript application/rss+xml image/svg+xml;

Protect against API denial-of-service floods by configuring IP rate limiting in http {} block: limit_req_zone $binary_remote_addr zone=api_limit:10m rate=10r/s;.

Frequently Asked Questions (FAQ)

How do I handle 502 Bad Gateway errors in Nginx?

A 502 error indicates Nginx received no response from the upstream application. Verify your backend service (Node.js/Python) is actively running on port 3000 with curl http://127.0.0.1:3000 or pm2 status.