location ~* ^(?!/system/files).*\.(js|css|png|jpg|jpeg|gif|ico)$ {
# If the image does not exist, maybe it must be generated by drupal (imagecache)
try_files $uri @drupal;
expires 7d;
log_not_found off;
}
http://klau.si/nginx-configuration-drupal
https://www.nginx.com/resources/wiki/start/topics/recipes/drupal/
https://github.com/perusio/drupal-with-nginx