If you have multiple sites under HAProxy a good way we have found to configure it is to have a frontend/backend configuration. The frontend is what HAProxy listens on and it sends connections to the backend(s) which can be different sites and use different pools of web servers.

Varnish Cache is an open source, state of the art web application accelerator. You install it on your web server and it makes your website fly.

Varnish is the key software that speeds up your web site. It is Open Source, built on industry standards and requires very few resources.

To map a domain to an S3 bucket

Nginx is a lightweight, high performance web server/reverse proxy and e-mail (IMAP/POP3) proxy. It runs on UNIX, GNU/Linux, BSD variants, Mac OS X, Solaris, and Microsoft Windows. According to Netcraft, 6% of all domains on the Internet use nginx webserver. Nginx is one of a handful of servers written to address the C10K problem. Unlike traditional servers, Nginx doesn't rely on threads to handle requests. Instead it uses a much more scalable event-driven (asynchronous) architecture. Nginx powers several high traffic web sites, such as WordPress, Hulu, Github, and SourceForge. This page collects hints how to improve the security of nginx web servers running on Linux or UNIX like operating systems.