Nginx as a Reverse Proxy

What is a Reverse Proxy?

Your Node.js app listens on port 3000. Nginx listens on port 80/443. Nginx receives every HTTP/HTTPS request from the internet and proxies it to your app. The client never connects directly to Node.js.

Benefits of a reverse proxy:

• SSL/TLS termination in one place — your app speaks plain HTTP internally
• Multiple apps on one server (different domains → different ports)
• Static file serving (much faster than Node.js)
• Request buffering (protects app from slow clients)
• Rate limiting, security headers, logging

Nginx Configuration Structure

# /etc/nginx/nginx.conf — main config
# /etc/nginx/sites-available/ — available site configs
# /etc/nginx/sites-enabled/  — symlinks to active configs
# /var/log/nginx/access.log  — all requests
# /var/log/nginx/error.log   — errors

# NEVER edit nginx.conf directly. Create files in sites-available/
# then symlink to sites-enabled/

A Production Nginx Config

# /etc/nginx/sites-available/yourapp.com

# Redirect HTTP → HTTPS
server {
    listen 80;
    server_name yourapp.com www.yourapp.com;
    return 301 https://$host$request_uri;
}

# HTTPS server
server {
    listen 443 ssl http2;
    server_name yourapp.com www.yourapp.com;

    # SSL certificates (managed by Certbot)
    ssl_certificate     /etc/letsencrypt/live/yourapp.com/fullchain.pem;
    ssl_certificate_key /etc/letsencrypt/live/yourapp.com/privkey.pem;

    # TLS settings
    ssl_protocols TLSv1.2 TLSv1.3;
    ssl_prefer_server_ciphers off;

    # Security headers
    add_header Strict-Transport-Security "max-age=31536000; includeSubDomains" always;
    add_header X-Content-Type-Options nosniff;
    add_header X-Frame-Options DENY;
    add_header Referrer-Policy "strict-origin-when-cross-origin";

    # Serve static files directly (fast)
    location /static/ {
        alias /var/www/yourapp/static/;
        expires 1y;
        add_header Cache-Control "public, immutable";
    }

    # Proxy everything else to Node.js
    location / {
        proxy_pass http://localhost:3000;
        proxy_http_version 1.1;

        # Required 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;

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

        # Timeouts
        proxy_read_timeout    60s;
        proxy_connect_timeout 10s;
        proxy_send_timeout    60s;
    }

    # Custom error pages
    error_page 500 502 503 504 /50x.html;
    location = /50x.html {
        root /usr/share/nginx/html;
        internal;
    }
}

Enable & Test the Config

# Create the config file
sudo nano /etc/nginx/sites-available/yourapp.com

# Test for syntax errors (ALWAYS do this before reloading)
sudo nginx -t

# Enable the site (symlink to sites-enabled)
sudo ln -s /etc/nginx/sites-available/yourapp.com \
           /etc/nginx/sites-enabled/

# Reload Nginx (zero-downtime config reload)
sudo systemctl reload nginx

# View access logs
sudo tail -f /var/log/nginx/access.log

# View error logs
sudo tail -f /var/log/nginx/error.log

Multiple Apps on One Server

Nginx lets you host multiple apps on one EC2 instance — great for cost savings on small projects:

# /etc/nginx/sites-available/api.yourapp.com
server {
    listen 443 ssl http2;
    server_name api.yourapp.com;
    # ... ssl certs ...
    location / {
        proxy_pass http://localhost:3001;  # API on 3001
    }
}

# /etc/nginx/sites-available/admin.yourapp.com
server {
    listen 443 ssl http2;
    server_name admin.yourapp.com;
    # ... ssl certs ...
    location / {
        proxy_pass http://localhost:3002;  # Admin on 3002
    }
}