extract word before first dot from url in nginx

Question

I use nginx

Assume that url "hello.test.example.com", hello example of dynamically subdomain, how can i get the word before the first dot in nginx config ?? the result must be "hello" ?

Answer 1

For example:

server {
    server_name ~^(?<subdomain>[^.]+)\.test\.example\.com$;
    ...
}

As of this configuration, the first part of subdomain name will be available as $subdomain variable value.