Nginx Configuration

Configuration Files Overview

Centmin Mod installs Nginx from source with a custom directory layout. Understanding where configuration files live is essential for managing your web server.

Main Configuration File

The primary Nginx configuration file controls global settings, worker processes, and includes all other config files:

/usr/local/nginx/conf/nginx.conf

Virtual Host Configs

Per-domain server block configurations are stored in the conf.d directory:

/usr/local/nginx/conf/conf.d/domain.com.conf
/usr/local/nginx/conf/conf.d/domain.com.ssl.conf

Key Directory Locations

Path	Purpose
/usr/local/nginx/conf/	Main config directory
/usr/local/nginx/conf/conf.d/	Virtual host configs
/home/nginx/domains/	Web document roots
/usr/local/nginx/logs/	Nginx log files
/usr/local/nginx/html/	Default document root

Global Settings

The main nginx.conf contains global directives that control Nginx's behavior at the process level.

Worker Processes & Connections

Centmin Mod automatically sets worker_processes to match your CPU core count. The worker_connections directive determines how many simultaneous connections each worker can handle.

worker_processes  auto;
worker_rlimit_nofile 260000;

events {
    worker_connections  10240;
    multi_accept on;
    accept_mutex on;
    accept_mutex_delay 200ms;
    use epoll;
}

Keepalive Settings

Keepalive connections allow multiple HTTP requests over a single TCP connection, reducing latency:

keepalive_timeout  10;
keepalive_requests 500;

Centmin Mod's default nginx.conf is already optimized for performance. Only modify these values if you understand the impact on your server's resource usage.

Virtual Host Configuration

Each website on your server gets its own Nginx server block (virtual host). Centmin Mod creates these automatically when you add a new Nginx vhost via centmin.sh menu option 2.

Server Block Structure

A typical vhost configuration file at /usr/local/nginx/conf/conf.d/domain.com.conf:

server {
    server_name domain.com www.domain.com;
    listen 80;

    access_log /home/nginx/domains/domain.com/log/access.log combined buffer=256k flush=5m;
    error_log  /home/nginx/domains/domain.com/log/error.log;

    root /home/nginx/domains/domain.com/public;

    # Nginx includes
    include /usr/local/nginx/conf/staticfiles.conf;
    include /usr/local/nginx/conf/drop.conf;
    include /usr/local/nginx/conf/errorpage.conf;

    location / {
        # ...
    }

    # PHP-FPM
    include /usr/local/nginx/conf/php.conf;
}

Document Root

Centmin Mod uses the following directory structure for each domain:

/home/nginx/domains/domain.com/
  public/       # Document root (web files go here)
  private/      # Private files (not web-accessible)
  log/          # Access and error logs
    access.log
    error.log
  backup/       # Backup directory

Nginx Includes

Centmin Mod uses modular include files to keep configurations organized. These are referenced inside each virtual host config.

Include File	Purpose
staticfiles.conf	Static file caching headers (images, CSS, JS, fonts)
drop.conf	Block access to sensitive files (.htaccess, .git, etc.)
errorpage.conf	Custom error page definitions (403, 404, 500, 502, etc.)
php.conf	PHP-FPM upstream and location blocks
503include-main.conf	Maintenance mode support
cloudflare.conf	Cloudflare real IP restoration

Note about staticfiles.conf

The staticfiles.conf include file has a .html, .htm, .txt location match which may interfere with rewrites of static files, especially if you use WordPress permalinks ending in .html. Remove the .html, .htm, .txt match from staticfiles.conf or choose a permalink format that does not use .html extensions. See issue #35 for details.

The relevant block in staticfiles.conf:

location ~* \.(html|htm|txt)$ {
    #add_header Pragma public;
    add_header Cache-Control "public, must-revalidate, proxy-revalidate";
    access_log off;
    expires 1d;
    break;
}

Performance Tuning

Centmin Mod ships with production-ready Nginx settings. Below are the key directives you may want to adjust based on your server's workload.

Buffer Sizes

Buffer settings control how Nginx handles request and response data in memory:

client_body_buffer_size    256k;
client_header_buffer_size  64k;
client_max_body_size       50m;
large_client_header_buffers 4 64k;

Timeouts

client_body_timeout   10;
client_header_timeout 10;
send_timeout          60;

Gzip Compression

Gzip compression reduces response sizes and improves page load times. Centmin Mod enables this by default:

gzip on;
gzip_vary on;
gzip_disable "MSIE [1-6]\.";
gzip_proxied any;
gzip_comp_level 5;
gzip_min_length 1024;
gzip_buffers 16 8k;
gzip_http_version 1.1;
gzip_types text/plain text/css application/json
           application/javascript text/xml
           application/xml application/xml+rss
           text/javascript image/svg+xml;

A gzip_comp_level of 5 provides a good balance between compression ratio and CPU usage. Higher levels yield diminishing returns while increasing CPU overhead.

Nginx Rewrite & App Configs

Nginx does not support Apache mod_rewrite syntax. You need to convert Apache rewrite rules to Nginx's HttpRewriteModule syntax. The official Nginx documentation provides examples for converting Apache rewrites.

Below are links to Nginx configuration examples and rewrite rules for popular web applications:

Cloudflare & Incapsula Proxies (HttpRealIpModule) Let's Encrypt Free SSL ownCloud Installation on Nginx WordPress Auto Installer (menu option 22) WordPress + WP-FFPC Plugin WordPress Basic + fastcgi_cache vBulletin 4.1.x Friendly URLs vBulletin vBSEO Rewrites XenForo SEO Friendly URLs Invision IP.Board 3.x & 4.1 vBulletin Connect 5 Vhost NodeBB Forum Laravel 5.1 Installation

Can't find what you need? Check the official Nginx forums and the Nginx Wiki.

Testing & Reloading

Always test your Nginx configuration before reloading to avoid downtime from syntax errors.

Test Configuration Syntax

Run the config test command to validate your changes:

nginx -t

A successful test outputs:

nginx: the configuration file /usr/local/nginx/conf/nginx.conf syntax is ok
nginx: configuration file /usr/local/nginx/conf/nginx.conf test is successful

Reload Nginx

After a successful test, gracefully reload Nginx to apply the new configuration without dropping active connections:

# Reload (graceful - preferred)
service nginx reload

# Or using the Nginx signal directly
nginx -s reload

# Restart (full stop/start - use only when needed)
service nginx restart

Always run nginx -t before service nginx reload. A failed reload due to syntax errors can prevent Nginx from accepting new connections even though existing ones continue to be served.