HAProxy reverse proxy for high availability environments

HAProxy is a TCP/HTTP reverse proxy which is particularly suited for high
availability environments. Indeed, it can:
 - route HTTP requests depending on statically assigned cookies
 - spread load among several servers while assuring server persistence
   through the use of HTTP cookies
 - switch to backup servers in the event a main one fails
 - accept connections to special ports dedicated to service monitoring
 - stop accepting connections without breaking existing ones
 - add, modify, and delete HTTP headers in both directions
 - block requests matching particular patterns
 - persists clients to the correct application server depending on
   application cookies
 - report detailed status as HTML pages to authenticated users from a URI
   intercepted from the application