Configure Nginx on CentOS after Installation – wiki基地

Configuring Nginx on CentOS After Installation: A Comprehensive Guide

After successfully installing Nginx on your CentOS system, the next crucial step is configuration. This involves understanding the core configuration file structure, customizing it to serve your specific needs, and managing various aspects like virtual hosts, SSL certificates, load balancing, and security. This guide provides a comprehensive walkthrough of configuring Nginx on CentOS, empowering you to leverage its full potential.

Understanding the Nginx Configuration File Structure:

Nginx’s primary configuration file is typically located at /etc/nginx/nginx.conf. This file governs the global settings for the Nginx server. Within this file, you’ll find several directives organized into blocks. Key blocks include:

• events: This block defines parameters related to connection processing, such as the maximum number of worker connections.
• http: This block encompasses most of the web server configuration. It includes directives for virtual hosts, MIME types, logging, and more.
• server: Nested within the http block, the server block defines the configuration for a specific website or virtual host. Each website or domain you want Nginx to serve will require its own server block.
• location: Inside the server block, location blocks allow you to define specific rules for handling different URLs or parts of your website. For example, you can configure different settings for serving static files, processing PHP scripts, or redirecting requests.
• upstream: Used for defining groups of servers for load balancing and other scenarios where requests need to be distributed across multiple backends.

Basic Configuration and Starting Nginx:

After installation, Nginx usually comes with a default configuration. You can verify its correctness by running:

bash
nginx -t

If the configuration is valid, you’ll see a “syntax is ok” message. To start Nginx, use:

bash
systemctl start nginx

You can then access the default Nginx welcome page in your web browser by navigating to your server’s IP address or domain name.

Customizing the Nginx Configuration:

Let’s delve into some common customization scenarios:

1. Configuring Virtual Hosts:

Virtual hosts allow you to host multiple websites on a single server. Each virtual host has its own server block within the nginx.conf file or, more commonly, in separate files within /etc/nginx/conf.d/.

Example:

“`nginx
server {
listen 80;
server_name example.com www.example.com;
root /var/www/example.com/html;
index index.html index.php;

location / {
    try_files $uri $uri/ =404;
}

location ~ \.php$ {
    fastcgi_pass   unix:/run/php-fpm/www.sock;
    fastcgi_index  index.php;
    include        fastcgi_params;
    fastcgi_param  SCRIPT_FILENAME  $document_root$fastcgi_script_name;
}

}
“`

This configuration defines a virtual host for example.com and www.example.com. It specifies the document root, the default index files, and how to handle PHP files using PHP-FPM.

2. Enabling SSL/TLS:

Securing your website with HTTPS is crucial. You’ll need an SSL certificate from a trusted Certificate Authority (CA). Once you have the certificate and key files, you can configure an HTTPS server block:

“`nginx
server {
listen 443 ssl;
server_name example.com www.example.com;
ssl_certificate /path/to/certificate.crt;
ssl_certificate_key /path/to/private.key;
ssl_protocols TLSv1.2 TLSv1.3;
ssl_ciphers HIGH:!aNULL:!MD5;

# ... other directives ...

}
“`

3. Setting up Redirects:

You can use the rewrite directive to redirect traffic from one URL to another:

“`nginx
server {
# … other directives …

rewrite ^/oldpage\.html$ /newpage.html permanent;

}
“`

This example redirects requests for /oldpage.html to /newpage.html with a 301 (permanent) redirect.

4. Configuring Logging:

Nginx logs access and error information. You can customize the log format and location in the http block or within specific server blocks.

nginx
access_log /var/log/nginx/access.log;
error_log /var/log/nginx/error.log;

5. Implementing Load Balancing:

Nginx can act as a load balancer, distributing traffic across multiple backend servers. You’ll define an upstream block to specify the backend servers:

“`nginx
upstream backend {
server backend1.example.com:80;
server backend2.example.com:80;
}

server {
# … other directives …

location / {
    proxy_pass http://backend;
}

}
“`

6. Optimizing Nginx Performance:

Several directives can be tuned to improve Nginx performance:

• worker_processes: Adjust the number of worker processes based on your server’s CPU cores.
• worker_connections: Defines the maximum number of connections each worker process can handle.
• keepalive_timeout: Controls how long keep-alive connections are maintained.
• client_max_body_size: Sets the maximum allowed size for client request bodies.

7. Securing Nginx:

Security is paramount. Consider these measures:

• Keep Nginx updated: Regularly update Nginx to patch security vulnerabilities.
• Disable unnecessary modules: Minimize the attack surface by disabling modules you don’t need.
• Limit access to sensitive directories: Use location blocks to restrict access to certain files or directories.
• Implement rate limiting: Prevent denial-of-service attacks by limiting the request rate from specific IP addresses.

Testing and Applying Changes:

After making any changes to the configuration file, always test the syntax:

bash
nginx -t

If the syntax is valid, reload Nginx to apply the changes without restarting the service:

bash
systemctl reload nginx

This comprehensive guide provides a solid foundation for configuring Nginx on CentOS. Remember to consult the official Nginx documentation for more in-depth information and advanced configurations. By understanding the core concepts and directives, you can fine-tune your Nginx server to achieve optimal performance, security, and reliability for your web applications.