We have mod_proxy doing balancing and working great with the exception of one thing, the health check. I'm talking about the heartbeat interval that tells mod_proxy if our java app instances are ok.
I'm pretty sure the issue is that the health check is not picking up the custom header I need to talk to a WebObjects application (java). I'm wondering if there is a way to configure it or if it simply isn't possible and am looking for advice on appending this header.
When setting up the proxy balancer, I initially had the same problem but it was quickly solved by adding the following line before the proxy balancer definition:
RequestHeader append x-webobjects-adaptor-version "mod_proxy"
What that did was add an arcane header that the java app (NeXT/Apple WebObjects) instances need to see in order for them to want to respond. Without it, they will drop the connection. Essentially what I'm doing here is replacing a special mod_webobjects Apache module with the built-in mod_proxy. This header is just something WO needs to see to allow communication.
But now, when I add health check parameters to the proxy balancer it thinks the app instances are all dead. It's because, for some reason, the custom header is not being used for the health check and the connection immediately drops. To confirm that was true, I modified the java application to force the header to be set when an incoming java HTTP request was received. While that did allow communication with health check, it causes other problems for me so is not a good workaround.
Does anyone know how to configure the mod_proxy health check to use a custom header? Or is it not possible currently? Thank you :-)
