Comprehensive Nginx Configuration Guide: Installation, Core Settings, Reverse Proxy, Load Balancing, Caching, HTTPS, CORS and Performance Tuning

Introduction – Nginx is an open‑source, high‑performance web and reverse‑proxy server widely used for static content delivery, load balancing, and API gateway functions.

Installation – On CentOS 7 you can install Nginx with yum install nginx -y. After installation, use rpm -ql nginx to view installed files and directories such as /etc/nginx/nginx.conf, /etc/nginx/conf.d/, and the default document root /usr/share/nginx/html.

Core Configuration – The main sections of nginx.conf are main, events, and http. Example snippets:

# main section
user  nginx;
worker_processes  auto;
error_log  /var/log/nginx/error.log warn;
pid        /var/run/nginx.pid;

# events section
events {
    use epoll;
    worker_connections 1024;
}

# http section
http {
    log_format  main  '$remote_addr - $remote_user [$time_local] "$request" '
                      '$status $body_bytes_sent "$http_referer" '
                      '"$http_user_agent" "$http_x_forwarded_for"';
    access_log  /var/log/nginx/access.log  main;
    sendfile        on;
    keepalive_timeout  65;
    include /etc/nginx/mime.types;
    default_type  application/octet-stream;
    include /etc/nginx/conf.d/*.conf;
}

Server Name & Location Matching – Use server_name for virtual hosts with exact, wildcard, or regex matching. The location directive supports modifiers (=, ~, ~*, ^~) and determines URI handling. Example:

server {
    listen 80;
    server_name www.example.com;
    location = /exact/ { root /var/www/exact; }
    location ~* \.(jpg|png|gif)$ { root /var/www/images; }
}

Reverse Proxy – Forward client requests to backend services using proxy_pass. The presence or absence of a trailing slash in the URL changes how the request URI is rewritten.

# No trailing slash – URI is passed unchanged
location /api/ { proxy_pass http://backend:8080; }

# With trailing slash – matched part is stripped
location /api/ { proxy_pass http://backend:8080/; }

Load Balancing – Define upstream server pools with upstream and select algorithms such as round‑robin (default), least_conn, ip_hash, or hash $request_uri. Example:

upstream backend_pool {
    server 10.0.0.1:8080;
    server 10.0.0.2:8080;
    least_conn;
}
server {
    listen 80;
    location / { proxy_pass http://backend_pool; }
}

Caching – Enable proxy caching with proxy_cache_path and proxy_cache. Configure cache key, validity, and bypass rules. Example:

proxy_cache_path /var/cache/nginx levels=1:2 keys_zone=cache_zone:10m max_size=2g inactive=60m;
upstream cache_backend { server 10.0.0.3:8080; }
server {
    listen 80;
    location / {
        proxy_cache cache_zone;
        proxy_cache_valid 200 5m;
        proxy_cache_key $request_uri;
        add_header X-Cache $upstream_cache_status;
        proxy_pass http://cache_backend;
    }
}

HTTPS – Configure SSL certificates with ssl_certificate and ssl_certificate_key. Example minimal SSL server block:

server {
    listen 443 ssl http2;
    server_name example.com;
    ssl_certificate /etc/nginx/ssl/example.crt;
    ssl_certificate_key /etc/nginx/ssl/example.key;
    ssl_protocols TLSv1.2 TLSv1.3;
    location / { root /usr/share/nginx/html; }
}

CORS – To allow cross‑origin requests, add appropriate Access-Control-Allow-Origin headers in a location block or use an if statement to set them conditionally.

Gzip Compression – Enable gzip with gzip on;, specify MIME types, compression level, and buffer settings. Example:

gzip on;
gzip_types text/plain text/css application/json application/javascript text/xml;
gzip_comp_level 6;

Architecture – Nginx uses a master‑worker model. The master process reads configuration and spawns multiple worker processes that handle client connections. Workers share memory zones for load‑balancing state, caching, and rate limiting. Reloading configuration sends a HUP signal to the master, which validates the new config, starts new workers, and gracefully shuts down the old ones.

Conclusion – By mastering Nginx’s core directives, upstream definitions, proxy settings, caching, SSL, CORS, and performance tuning, developers can build robust, scalable, and secure web infrastructures.