How to use wildcards or regular expressions in server_name?

When using server_name in Nginx to match multiple domains or subdomains, it can be achieved through wildcards and regular expressions. 1. When using wildcards, the asterisk can only be used for the beginning or ending, and must be a complete label boundary. For example, .example.com can match first-level subdomains but does not include root domains or multi-level subdomains. If you need to match both root domains and first-level subdomains, it should be written as example.com *.example.com; 2. When using regular expressions, you must start with ~, such as ~^\w .(dev|test)$ can match domain names ending with .dev or .test, and support capture group calls; 3. The matching priority is the exact name > Longest wildcard prefix > Longest wildcard suffix > Regular expressions, and the default case is insensitive. It is recommended to use wildcards for simple matching, and use regulars for complex scenarios. After modifying configuration, the service should be tested and overloaded.

When using server_name in Nginx configuration, if you want to match multiple domains or subdomains, you can simplify the configuration with wildcards and regular expressions. This approach is particularly suitable for scenarios where a large number of dynamic subdomains or pan-domains are required.

Here are some practical usages and suggestions.

Use wildcards to match subdomains

Nginx supports the use of asterisks * for wildcard matching, but it should be noted that it can only be used for the beginning or end, and must be a complete label boundary.

For example:

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

    # Processing logic}

This configuration will match a.example.com , b.example.com , but will not match example.com or abexample.com .

If you want to match both the root domain and any first-level subdomain, you can write it like this:

 server_name example.com *.example.com;

Use regular expressions for more flexible matching

Regular expressions can be used when there are insufficient wildcards. When using regular in server_name , you need to use a wavy line ~ to indicate that the regular mode is turned on.

For example, you want to match all domain names ending with .dev or .test :

 server {
    listen 80;
    server_name ~^\w \.(dev|test)$;

    # Processing logic}

In this example:

• ^ means the beginning
• \w Match one or more word characters (letters, numbers, underscores)
• \. point number
• (dev|test) means dev or test
• $ means end

Note: Capture groups in regular expressions can be called via variables in subsequent configurations, such as $1 , $2 , etc.

Frequently Asked Questions and Precautions

• Priority issue : Nginx matches server_name in the order in which the exact name > longest wildcard prefix > longest wildcard suffix > regular expressions. So if you have multiple server blocks, be careful about the priority between them.
• Case is insensitive by default : Nginx is insensitive to domain names by default, which means that Example.com and example.com are equivalent.
• Don't abuse the regulative : Although the regulative is powerful, if it is just a simple match, it is clearer and more efficient to use wildcards.
• Testing the configuration is very important : after modifying the configuration, be sure to run nginx -t to check whether the syntax is correct, and then the overloading service takes effect.

Basically that's it. Mastering the use of wildcards and regular expressions can make you more comfortable when configuring Nginx, especially when facing complex scenarios such as multi-tenant and multi-subdomains.

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