mod proxy logging

How to add backend server address to frontend logs

[seren]

I have a question that I'm surprised I haven't been able to find an answer to.

I'm using mod_proxy with Apache 2.2.9 to forward requests to a dozen back-end servers running tomcat. For troubleshooting, I'd like to be able to look at the apache logs on the front-end and determine which back-end server mod_proxy forwarded the request to, but I can't see any way to do this.

Am I overlooking something or does mod_proxy just not do this? It seems like a pretty basic feature. Thanks in advance.