NGINX base module directives: The complete guide

Introduction

In the world of web server management, NGINX has become synonymous with performance, efficiency, and reliability. One key to NGINX’s flexibility is its rich set of directives provided by various modules. These directives are the building blocks of NGINX configurations, enabling administrators to fine-tune their web servers for optimal performance, security, and resource utilization.

This guide explores the core directives of NGINX from the base module, which serve as a foundation for any NGINX setup. Understanding these directives is essential for both newcomers and seasoned administrators looking to harness the full potential of their web servers.

Understanding Configuration File Structure

Before diving into directives, it’s crucial to understand NGINX’s configuration file structure. Here’s an example fragment to illustrate:

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

The structure typically consists of directives organized within context blocks like http, server, and location. Each directive has a specific role and operates within its enclosing context.

Essential NGINX Base Module Directives

Now let’s review some essential directives from the base module.

listen

This directive specifies the IP address and port on which a server block listens for client requests. It can also accept additional parameters to define default server and SSL-related properties.

server {
  listen 443 ssl default_server;
  listen [::]:443 ssl default_server;
  ...
}

Here, NGINX listens on port 443 for both IPv4 and IPv6 connections with SSL enabled.

server_name

This directive sets the domain name that the server block will respond to.

server {
  listen 80;
  server_name example.com www.example.com;
  ...
}

NGINX will handle requests for ‘example.com’ and ‘www.example.com’ using this server block.

root

The root directive defines the document root for the request being processed.

location / {
  root /var/www/html;
  ...
}

All requests will be served from the /var/www/html directory.

index

This directive specifies one or more index files that NGINX should look for when a directory is requested.

location / {
  index index.html index.htm;
  ...
}

If a directory is requested, such as ‘/‘, NGINX attempts to serve index.html, then index.htm, if the former doesn’t exist.

error_page

The error_page directive allows configuring custom error pages for different HTTP statuses.

server {
  error_page 404 /custom_404.html;
  location = /custom_404.html {
    root /var/www/html;
    internal;
  }
  ...
}

Here, a custom 404 page is specified within the server block.

Variables and Inheritance in NGINX

NGINX also uses variables for dynamic configurations and inherits certain parameters from one level to the next.

http {
  server_tokens off;
  ...
  server {
     server_name example.com;
     ...
  }
}

Directives like server_tokens set in the http block are inherited by all server blocks unless explicitly overridden.

Advanced Directives and Customization

While the basics covered are critical, NGINX’s real power lies in its advanced directives and extending functionality via additional modules.

include

The include directive allows including other configuration files.

http {
  include /etc/nginx/conf.d/*.conf;
  ...
}

Third-party modules often introduce their own directives that, when used in tandem with base directives, allow for sophisticated configurations addressing specific needs like caching, load balancing, and security enhancements.

Performance Tuning with Directives

Beyond basic configurations, performance tuning is a major reason NGINX is favored in production environments. Directives such as keepalive_timeout and client_max_body_size can be adjusted to optimize server performance or resource usage.

Conclusion

The NGINX base module directives discussed in this guide are just the beginning. When used correctly, they set the stage for a secure, high-performance web environment. This foundational knowledge will serve you well as you discover more complex configurations and directives provided by NGINX’s rich ecosystem.