nginx

Nginx

Nginx is a high-performance HTTP server, reverse proxy, and load balancer known for its asynchronous event-driven architecture and native HTTP/3 support.

When to Use

High-Performance HTTP Reverse Proxy & Web Server: Serving millions of requests per second with an asynchronous event-driven architecture.
SSL/TLS Termination & HTTP/2/HTTP/3: Offloading cryptographic handshakes and managing Let's Encrypt certificates.
Upstream Load Balancing & Microservice Routing: Distributing traffic across backend clusters with keepalive connection pools.
Rate Limiting & DDoS Defense: Enforcing token-bucket rate limits (limit_req_zone) per IP address.

Quick Start

# nginx.conf
server {
    listen 443 quic reuseport;
    listen 443 ssl;
    http2 on;

server_name example.com;
ssl_certificate cert.pem;
ssl_certificate_key key.pem;

location / {
    proxy_pass http://localhost:3000;
    add_header Alt-Svc 'h3=":443"; ma=86400';
}

}


## Core Concepts

### Hardened Reverse Proxy Configuration with HTTP/2 and Upstream Keepalive

Production server configuration with security headers:

```nginx
# /etc/nginx/nginx.conf
user nginx;
worker_processes auto;
worker_rlimit_nofile 65535;

events {
    worker_connections 8192;
    use epoll;
    multi_accept on;
}

http {
    include /etc/nginx/mime.types;
    default_type application/octet-stream;

    # Performance optimizations
    sendfile on;
    tcp_nopush on;
    tcp_nodelay on;
    keepalive_timeout 65;
    types_hash_max_size 2048;

    # Rate limiting zone: 10MB memory, 50 requests/second per IP
    limit_req_zone $binary_remote_addr zone=api_limit:10m rate=50r/s;

    upstream backend_nodes {
        server 10.0.1.10:8080 max_fails=3 fail_timeout=10s;
        server 10.0.1.11:8080 max_fails=3 fail_timeout=10s;
        keepalive 32; # Cache up to 32 idle connections to backends
    }

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

        ssl_certificate /etc/letsencrypt/live/api.example.com/fullchain.pem;
        ssl_certificate_key /etc/letsencrypt/live/api.example.com/privkey.pem;
        ssl_protocols TLSv1.2 TLSv1.3;
        ssl_ciphers ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256;
        ssl_prefer_server_ciphers off;

        # Security Headers
        add_header Strict-Transport-Security "max-age=63072000; includeSubDomains; preload" always;
        add_header X-Frame-Options "DENY" always;
        add_header X-Content-Type-Options "nosniff" always;

        location / {
            limit_req zone=api_limit burst=20 nodelay;

            proxy_pass http://backend_nodes;
            proxy_http_version 1.1;
            proxy_set_header Connection ""; # Required for upstream keepalive
            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;

            proxy_connect_timeout 5s;
            proxy_read_timeout 60s;
        }
    }
}

Static Asset Caching & Single Page Application Routing

Serving static SPAs with browser caching:

server {
    listen 80;
    server_name app.example.com;
    root /var/www/app/dist;
    index index.html;

    # Immutable caching for hashed assets
    location ~* \.(?:css|js|woff2?|png|jpg|webp)$ {
        expires 1y;
        add_header Cache-Control "public, max-age=31536000, immutable";
        access_log off;
    }

    # SPA route fallback
    location / {
        try_files $uri $uri/ /index.html;
    }
}

Validating and Reloading Configuration

Testing syntax before reloading:

# Test configuration syntax
nginx -t

# Gracefully reload configuration without dropping connections
nginx -s reload

Common Patterns

Hardened Reverse Proxy with SSL and Rate Limiting

Problem: Slow APIs and vulnerability to brute-force DDoS attacks on login endpoints.

Solution: Configure Nginx with connection limits and proxy buffering:

limit_req_zone $binary_remote_addr zone=api_limit:10m rate=10r/s;

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

    ssl_certificate /etc/letsencrypt/live/api.example.com/fullchain.pem;
    ssl_certificate_key /etc/letsencrypt/live/api.example.com/privkey.pem;

    location / {
        limit_req zone=api_limit burst=20 nodelay;

        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_set_header X-Forwarded-Proto $scheme;
    }
}

Best Practices

Do:

Always test configuration syntax with nginx -t before issuing nginx -s reload.
Set proxy_http_version 1.1 and proxy_set_header Connection "" when using upstream keepalive pools.
Enable limit_req_zone to protect login, payment, and search endpoints against abuse.
Enable server_tokens off; to prevent revealing Nginx version information to attackers.

Don't:

Use if directives inside location blocks (if is evil in Nginx); use try_files or maps.
Run worker processes as root; use unprivileged nginx or www-data system users.
Omit Strict-Transport-Security headers on production HTTPS endpoints.

Troubleshooting

Error	Cause	Solution
`502 Bad Gateway`	Upstream backend server offline or port unreachable.	Verify upstream application is listening on specified port.
`nginx: [emerg] bind() to 0.0.0.0:80 failed (98: Address already in use)`	Another web server process already listening on port 80.	Find conflicting process: `sudo lsof -i :80` and stop it.
`413 Request Entity Too Large`	Client uploaded file larger than default `client_max_body_size` (1M).	Increase setting: `client_max_body_size 50M;` in `http` or `server` block.

References

Nginx Documentation