Understanding the Nginx 'server' Block

Nginx

Nginx server {} blocks are configuration blocks that define how Nginx handles requests for specific domains or IP addresses. This guide breaks down each component of a server block to help you understand its purpose and functionality.

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What is a Server Block?

A server block in Nginx is a configuration section that specifies how requests to a particular domain or IP address should be processed. It is defined within the http context of the Nginx configuration file.

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Anatomy of a Server Block

Below is an example of a basic Nginx server block:

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

    root /var/www/example.com;
    index index.html;

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

Let’s break down each component:

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listen

The listen directive specifies the port and optionally the IP address that Nginx should listen on for incoming requests.

• listen 80; → Tells Nginx to listen on port 80 (HTTP).
• listen [::]:80; → Enables IPv6 support for port 80.
• listen 443 ssl; → Configures Nginx to listen on port 443 (HTTPS) with SSL.

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server_name

The server_name directive defines the domain names or IP addresses that this server block will respond to.

• server_name example.com www.example.com; → Matches requests for example.com and www.example.com.
• Use _ as a wildcard to match any domain: server_name _;.

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root

The root directive specifies the directory where the website files are located.

• root /var/www/example.com; → Sets the document root to /var/www/example.com.

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index

The index directive defines the default file to serve when a directory is requested.

• index index.html; → Serves index.html when a user accesses the root directory.

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location

The location block defines how Nginx should handle requests for specific URIs or patterns.

• location / { ... } → Matches requests to the root (/) of the domain.
• try_files $uri $uri/ =404; → Tries to serve the requested file ($uri), then the directory ($uri/), and returns a 404 error if neither exists.

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Additional Directives

error_page

Defines custom error pages for specific HTTP status codes.

error_page 404 /custom_404.html;

return

Returns a specific HTTP status code or redirects the request.

return 301 https://example.com$request_uri;

proxy_pass

Used for reverse proxying requests to another server.

location /api/ {
    proxy_pass http://backend_server;
}

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Conclusion

Understanding the components of an Nginx server block is essential for configuring your web server effectively. By mastering these directives, you can customize how Nginx handles requests, serves content, and interacts with backend services. For more advanced configurations, refer to the Nginx documentation.