server_name-examples.md

The server_name directive in Nginx is used to define which domain(s) or subdomain(s) a server block should respond to. You can configure Nginx to handle specific domain names, wildcard domains, or even catch-all configurations. Here are several examples to help illustrate how server_name works in different scenarios.

1. Single Domain

This is the most common use case, where Nginx responds to a specific domain name.

Example:

server {
    listen 80;
    server_name example.com;

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

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

• server_name example.com;: Nginx will handle requests for example.com.
• Requests for http://example.com will serve files from /var/www/example.

2. Multiple Domain Names (Aliases)

You can set up Nginx to handle multiple domain names for a single server block.

Example:

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

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

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

• server_name example.com www.example.com;: Nginx will handle requests for both example.com and www.example.com.
• This is useful when you want the same content served for both the base domain and its www version.

3. Wildcard Subdomains

You can use a wildcard * to match all subdomains of a domain.

Example:

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

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

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

• server_name *.example.com;: Nginx will handle any subdomain of example.com (e.g., app.example.com, blog.example.com, dev.example.com).
• Requests for subdomain.example.com will be served from the same root directory.

4. Exact Domain Name (Prevent Subdomain Matching)

If you want to strictly match a single domain without allowing subdomains, use = before the domain name.

Example:

server {
    listen 80;
    server_name =example.com;

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

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

• server_name =example.com;: Nginx will handle requests only for example.com and not for any subdomains like www.example.com or app.example.com.

5. Catching All Domains (Catch-All)

You can use an underscore (_) as a wildcard to match any domain name that doesn't match any other server_name directive.

Example:

server {
    listen 80 default_server;
    server_name _;

    root /var/www/default;
    index index.html;

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

• server_name _;: This acts as a catch-all for any requests that don’t match any other server_name configurations. It will catch requests for unknown or mismatched domain names.
• This is useful as a fallback when you want to serve a default page or handle requests to any undefined domains.

6. Multiple Server Blocks for Different Domains

You can have different server blocks for handling various domains with different configurations.

Example:

server {
    listen 80;
    server_name example.com;

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

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

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

    root /var/www/api;
    index index.html;

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

• server_name example.com;: This block handles requests for example.com.
• server_name api.example.com;: This block handles requests for api.example.com.
• Each domain can serve different content from different root directories (/var/www/example and /var/www/api).

7. Using Regex for Advanced Domain Matching

You can use regular expressions (regex) to match more complex domain patterns. Note that you need to prefix the server_name with ~ for regex.

Example:

server {
    listen 80;
    server_name ~^www\.(.+)\.com$;

    root /var/www/regex;
    index index.html;

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

• server_name ~^www\.(.+)\.com$;: Nginx will match any domain that starts with www. and ends with .com, such as www.example.com or www.test.com.
• This can be useful for complex domain matching scenarios.

8. Redirecting www to Non-www

You can use server_name in combination with a redirect to ensure that requests to www.example.com are redirected to example.com (non-www version).

Example:

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

    return 301 http://example.com$request_uri;
}

server {
    listen 80;
    server_name example.com;

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

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

• The first server block redirects www.example.com to example.com.
• The second server block serves the actual content for example.com.

9. Redirecting HTTP to HTTPS

If you want to redirect all HTTP traffic to HTTPS for a specific domain, you can use the following configuration:

Example:

server {
    listen 80;
    server_name example.com;

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

• This block ensures that all HTTP requests are redirected to the HTTPS version of example.com.

Summary:

• server_name defines which domains a particular server block will handle.
• You can specify one or more domains, use wildcards, regular expressions, or set up catch-all blocks.
• This allows you to configure different behaviors for different domains or subdomains on the same Nginx server.

These examples provide flexibility to manage multiple domains and requests efficiently within your Nginx configuration.