Nginx: Core Concepts and Configuration

Basic Directives and Configuration Files#

Nginx configuration is built on a structured format consisting of key directives that control how the server handles connections, processes requests, and manages content delivery. Understanding these directives is essential for configuring and optimizing Nginx effectively.

• Key Directives:

  • worker_processes: Defines the number of worker processes handling client requests. More workers improve performance for high-traffic sites.
  • events {}: Manages connection handling, ensuring efficient request processing.
  • http {}: The main section where web server settings, including caching, logging, and compression, are defined.
  • server {}: Defines settings for individual websites or applications, such as domains, ports, and document roots.
  • location {}: Specifies how Nginx handles different URLs and routes requests.

• Checking the Nginx Configuration: Before applying changes, validate the configuration syntax:

  nginx -t

• Reloading Nginx After Changes: Apply configuration updates without downtime:

  sudo systemctl reload nginx

HTTP Configuration and Server Blocks#

Server blocks (also known as virtual hosts) define the behavior of Nginx for different domains and applications. They allow multiple websites to run on a single server with separate configurations.

• Defining Server Blocks:

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

  This example sets up a basic web server that listens on port 80 and serves content from /var/www/example.

• Managing Multiple Server Blocks: Each domain or application should have its own server {} block to ensure isolation.

• Enabling and Disabling Server Blocks: Use symbolic links to activate or deactivate configurations without modifying files:

  ln -s /etc/nginx/sites-available/example.com /etc/nginx/sites-enabled/

Reverse Proxy and Load Balancing#

Nginx can act as a reverse proxy, forwarding client requests to backend servers, improving security and performance.

• Setting Up a Reverse Proxy:

  server {
      listen 80;
      server_name example.com;
      location / {
          proxy_pass http://127.0.0.1:5000;
          proxy_set_header Host $host;
          proxy_set_header X-Real-IP $remote_addr;
      }
  }

  This setup forwards all incoming requests to a backend application running on port 5000.

• Implementing Basic Load Balancing: Distributing traffic across multiple servers improves availability and performance:

  upstream backend {
      server 192.168.1.10;
      server 192.168.1.11;
  }
  
  server {
      listen 80;
      location / {
          proxy_pass http://backend;
      }
  }

  This configuration routes incoming requests to multiple backend servers in a round-robin fashion.

Static and Dynamic Content Handling#

Nginx is highly efficient at serving static files, such as HTML, CSS, JavaScript, and images, while also supporting dynamic applications through reverse proxying.

• Serving Static Content:

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

  This example configures Nginx to serve static files from /var/www/html when requests match /static/.

• Proxying Requests to Dynamic Applications: Nginx can forward requests to backend services like PHP, Python, or Node.js applications:

  location / {
      proxy_pass http://localhost:3000;
  }

  This setup directs all requests to a locally running application on port 3000.

Hands-On Exercise#

To reinforce these concepts, try the following hands-on tasks:

• Create and configure multiple server blocks for different domains.
• Set up Nginx as a reverse proxy for a backend application.
• Configure static and dynamic content handling to serve both files and web applications.
• Test and reload Nginx configuration to apply changes effectively.

By mastering these core concepts, you’ll gain the foundational knowledge needed to deploy and manage Nginx effectively for various use cases.