Nginx subdomain to subdomain redirect not working

Question

The config below redirects to .another-domain.com with empty subdomain name. What am I doing wrong?

server {
  server_name ~^(\w+)\.domain\.com$;
  location / {
    rewrite ^ $scheme://$1.another-domain.com$request_uri permanent;
  }
}

Answer 1

NGINX docs mention that for the server_name directive:

the digital references can easily be overwritten

Thus you should use named captures.

Also, since you're performing site-wide redirect without complicated URL substitutions, you can simply use return directly in the server context:

server {
  server_name ~^?(?<subdomain>\w+)\.domain\.com$;
  return 301 $scheme://$subdomain.another-domain.com$request_uri;
}

Also, as per comment above, make sure this isn't the default server in your NGINX configuration. You can do that by simply supplying default_server flag in the other server's listen directive.