Comprehensive Guide to Nginx: Core Concepts, Configuration, and Advanced Features

Nginx is a lightweight, high‑performance web server and reverse proxy that excels in handling massive concurrent connections thanks to its event‑driven, non‑blocking architecture.

Key advantages include low memory consumption, simple configuration, built‑in health checks, support for load balancing, SSL termination, and the ability to serve static content directly.

Typical deployment scenarios are static website hosting, reverse proxy for backend services, API gateway, virtual hosting based on domain or IP, and CDN edge caching.

When a request arrives, the master process parses the configuration, creates worker processes, and each worker uses an event loop (epoll) to accept connections, read/write data, and hand off completed requests without blocking, allowing a small number of workers to handle thousands of connections.

Basic configuration uses server and location blocks. For example:

server {
    listen 80;
    server_name www.example.com;
    location / {
        root /data/www;
        index index.html index.htm;
    }
}

Load balancing is defined with an upstream block and can use several algorithms:

upstream backend {
    # round‑robin (default)
    server 192.168.0.12;
    server 192.168.0.13;
}

# weighted round‑robin
upstream weighted {
    server 192.168.0.12 weight=2;
    server 192.168.0.13 weight=8;
}

# IP hash
upstream iphash {
    ip_hash;
    server 192.168.0.12;
    server 192.168.0.13;
}

Rate limiting uses the ngx_http_limit_req_module. A typical rule limits a client to one request per minute with a burst of five immediate requests:

limit_req_zone $binary_remote_addr zone=one:10m rate=1r/m;
server {
    location /api {
        limit_req zone=one burst=5 nodelay;
        proxy_pass http://backend;
    }
}

Connection limiting is handled by ngx_http_limit_conn_module to restrict simultaneous connections per IP or per server name:

limit_conn_zone $binary_remote_addr zone=addr:10m;
limit_conn_zone $server_name zone=servername:10m;

server {
    location / {
        limit_conn addr 10;
        limit_conn servername 100;
    }
}

Additional features include health checks (built‑in or via nginx_upstream_check_module), gzip compression for text assets, and high‑availability setups using multiple upstream servers with appropriate timeout settings.