location  /blank/{
     add_header Cache-Control "no-store, no-cache";
     proxy_pass http://10.68.50.74:80/;
}

  location ^~ /blank/css/ {
      expires 168h;
      add_header Pragma public;
      add_header Cache-Control "public,must-revalidate,proxy-revalidate";
                           proxy_pass http://10.68.50.74:80/css/;
    }
  location ^~ /blank/js/ {
      expires 10m;
      add_header Pragma public;
      add_header Cache-Control "public,must-revalidate,proxy-revalidate";
                           proxy_pass http://10.68.50.74:80/js/;
    }