I just spent more time than I would have liked to searching for info on providing HA/LB via CARP (and possibly other tools) for individual services (such as http) rather than IP addresses. I was surprised to find just about nothing on the topic since it seems like something people would want to use CARP for.
For example, lets say I have two machines set up as web servers, sharing an IP address and load balanced with CARP. The httpd on one host dies but it's interface is fine. Doesn't that mean CARP has no effect and approximately half the requests going to the virtual host ip address will timeout? That sucks. I'm guessing you can configure ifstated to run curl or something every few seconds to monitor the httpd and respond by taking the CARP interface down or rig up some hoc shell script to do roughly the same thing. Right? Seems like someone, somewhere must have thought about doing this with airline food before. Am I right folks??
