nginx rails configuration, with assets expiration

nginx.conf

 server {
    listen   80;
    server_name APP.com;
    rewrite ^/(.*) http://www.APP.com/$1 permanent;
  }

  server {
    listen 80;
    server_name www.APP.com;
    root /home/USER/sites/APP/current/public;

    passenger_enabled on;
    passenger_min_instances 1;
    passenger_friendly_error_pages off;

    client_max_body_size 4M;

    gzip on;
    gzip_comp_level 3;
    gzip_min_length 1000;
    gzip_buffers 16 8k;
    gzip_types text/plain text/css application/json application/x-javascript text/xml application/xml application/xml+rss text/javascript;
    gzip_disable "MSIE [1-6]\.";

    # expires headers only if have ?123 timestamp at end, with extra check for js only in javascripts folder, to allow actions with .js format specification
    location ~* (\.ico|\.css|\.gif|\.jpe?g|\.png|javascripts.+\.js) {
      if ($args ~* [0-9]+$) {
          expires max;
          access_log off;
          break;
      }
    }