Nginx rewrite non-www-prefixed domain to www-prefixed domain

Question

I see the Nginx HttpRewriteModule documentation has an example to rewrite a www-prefixed domain to a non-www-prefixed domain:

if ($host ~* www\\.(.*)) {
  set $h         


        

Answer 1

if ($host ~* ^[^.]+\.[^.]+$) {
    rewrite ^(.*)$ http://www.$host$1 permanent;
}

It's only possible to get valid hostnames because the request will never make it to your server otherwise, so there's no need to build your own validation logic.