Nginx as a Reverse Proxy: Load Balancing & SSL Termination

Nginx Reverse Proxy with SSL and Load Balancing

Nginx is the most deployed reverse proxy/load balancer. This covers a production-ready setup with Let's Encrypt SSL.

Installation

BASH

apt install nginx certbot python3-certbot-nginx

Basic Reverse Proxy

NGINX

# /etc/nginx/sites-available/app.conf
server {
    listen 80;
    server_name app.example.com;
    return 301 https://$host$request_uri;
}

server {
    listen 443 ssl http2;
    server_name app.example.com;

    ssl_certificate /etc/letsencrypt/live/app.example.com/fullchain.pem;
    ssl_certificate_key /etc/letsencrypt/live/app.example.com/privkey.pem;
    ssl_protocols TLSv1.2 TLSv1.3;
    ssl_ciphers HIGH:!aNULL:!MD5;

    location / {
        proxy_pass http://127.0.0.1:3000;
        proxy_http_version 1.1;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection 'upgrade';
        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_cache_bypass $http_upgrade;
    }
}

Load Balancing Multiple Backends

NGINX

upstream backend {
    least_conn;
    server 10.0.0.10:3000 weight=3;
    server 10.0.0.11:3000 weight=2;
    server 10.0.0.12:3000 weight=1 backup;
    keepalive 32;
}

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

    location / {
        proxy_pass http://backend;
        proxy_next_upstream error timeout;
        health_check interval=10 fails=3 passes=2;
    }
}

Rate Limiting

NGINX

# /etc/nginx/nginx.conf
http {
    limit_req_zone $binary_remote_addr zone=api:10m rate=10r/s;
    limit_conn_zone $binary_remote_addr zone=conn:10m;

    server {
        location /api/ {
            limit_req zone=api burst=20 nodelay;
            limit_conn conn 10;
        }
    }
}

Let's Encrypt Certificate

BASH

certbot --nginx -d app.example.com -d www.app.example.com
# Auto-renewal via systemd timer (enabled by default)
certbot renew --dry-run

Security Headers

NGINX

add_header Strict-Transport-Security "max-age=31536000; includeSubDomains" always;
add_header X-Content-Type-Options nosniff;
add_header X-Frame-Options SAMEORIGIN;
add_header X-XSS-Protection "1; mode=block";
add_header Referrer-Policy "strict-origin-when-cross-origin";