Master Nginx Basics: From Installation to Advanced Configuration

Nginx Overview

Nginx is a lightweight, high‑performance web server and reverse‑proxy that excels at handling massive concurrent connections using asynchronous, non‑blocking I/O and the epoll model.

Key Advantages

High concurrency and low memory usage

Efficient I/O multiplexing (epoll)

Built‑in reverse‑proxy and mail (IMAP/POP3) support

Installation

YUM Installation

yum install nginx

Source Compilation

# Download source
wget https://nginx.org/download/nginx-1.20.2.tar.gz
 tar -xf nginx-1.20.2.tar.gz
cd nginx-1.20.2
# Configure with desired modules and prefix
./configure --prefix=/opt/nginx1.20.2 \
    --user=nginx --group=nginx \
    --with-http_ssl_module \
    --with-http_stub_status_module \
    --with-http_random_index_module \
    --with-http_sub_module \
    --with-http_gzip_module
make && make install

Configuration File Structure

# Global settings (main context)
user  nginx;
worker_processes  auto;
error_log  /var/log/nginx/error.log notice;
pid        /var/run/nginx.pid;

# Events block
events {
    worker_connections  1024;
}

# HTTP block
http {
    include       mime.types;
    default_type  application/octet-stream;
    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/conf.d/*.conf;
}

# Server block (virtual host)
server {
    listen       80;
    server_name  example.com;
    root         /usr/share/nginx/html;
    index        index.html index.htm;
    location / {
        try_files $uri $uri/ =404;
    }
}

Important Modules

ngx_http_stub_status_module – provides real‑time connection statistics via /status location.

ngx_http_random_index_module – serves a random index file when random_index on; is set.

ngx_http_sub_module – replaces strings in response bodies using sub_filter.

ngx_http_gzip_module – compresses responses; enable with gzip on;.

ngx_http_headers_module – controls caching via expires directives.

ngx_http_limit_req_module and ngx_http_limit_conn_module – limit request rate and concurrent connections.

ngx_http_referer_module – implements hotlink protection.

Logging

Typical log format records client IP, user, timestamp, request line, status, bytes sent, referrer and user‑agent. Example:

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;

Virtual Hosts

Define separate server blocks for each domain or IP. Example:

server {
    listen 80;
    server_name www.example.com;
    root /opt/example;
    index index.html;
}

server {
    listen 80;
    server_name www.another.com;
    root /opt/another;
    index index.html;
}

HTTPS

Enable SSL by adding listen 443 ssl; and specifying ssl_certificate and ssl_certificate_key files.

Rewrite Rules

Use rewrite directives for URL redirection and rewriting, e.g.:

rewrite ^/old/(.*)$ /new/$1 permanent;

Smooth Upgrade

When Nginx is compiled from source, you can upgrade without dropping connections by sending kill -USR2 $master_pid, which spawns a new master process while the old one continues serving existing requests. Switch back with kill -QUIT $old_master_pid if needed.