Nginx

These options are necessary to configure in nginx configuration file usable contexts are (http, server, location):

proxy_buffer_size          128k;
proxy_buffers              4 256k;
proxy_busy_buffers_size    256k;
proxy_temp_file_write_size 256k;

Further links that can be usefull:

http://www.nginxtips.com/504-gateway-time-out-using-nginx/

http://stackoverflow.com/questions/561946/how-do-i-prevent-a-gateway-timeout-with-fastcgi-on-nginx