I would like to set up Apache 2 as a reverse proxy using name-based virtual hosts to decide how requests are routed to back-end servers. Simple enough.
The catch is that these back-end servers may be added and removed in a dynamic fashion. My first idea was to programmatically re-write an Apache configuration file and call
apachectl graceful every time a back-end server goes up or down. This does not seem like the correct solution. What is a better way to accomplish this?
I need to be able to gracefully transfer handling of names over to different back-end servers. For instance, Backend-Server-A might be handling requests for example.com. A monitoring process might decide that Backend-Server-A is stale (too much memory usage, there's new version of the server code to handle example.com, etc). The monitoring process starts Backend-Server-B which will soon handle requests for example.com. Apache should direct any new requests for example.com to Backend-Server-B, but allow any pending requests currently being handled by Backend-Server-A to complete before Backend-Server-A is shut down by my monitoring process.
(Note: I originally posted this on Stack Overflow.)