nginx rewrite all subdomains to www

Question

I'm trying to find the right regex to rewrite all subdomains to www.

so for example w7w.domain.com to www.domain.com

or alskdaslkdja.domain.com to www.domain.com

i've tried many things, my last attempt was:

if ($host ~* (?!www\.)(.*))
{
  set $host_without_www www.$1;
  rewrite ^(.*)$ http://$host_without_www$1 permanent; 
}

but that didn't work either.

i need to catch these and can't just do a wildcart rewrite to the www.domain.com because i have several domains being served on this instance.

any ideas?

Answer 1

server {
    listen          xx.xx.xx.xx:80;
    server_name     www.example.com;
    # ....
}
server {
    listen          xx.xx.xx.xx:80;
    server_name     example.com *.example.com;
    rewrite         ^ http://www.example.com$request_uri? permanent;
}

Answer 2

server {
  # Prefix server wildcards are checked before regexes, so this
  # will catch anything starting with www.
  server_name www.*;
}

server {
  # This should redirect anything that didn't match the first
  # server to domain.tld

  # I think this regex will capture the domain.tld
  server_name ~(?<domain>[^.]+\.[^.]+)$

  rewrite ^ http://www.$domain$request_uri? permanent;
}