We use the Varnish HTTP accelerator, and heartbeat. It would be good to have heartbeat aware of varnish so it can handle moving IPs and starting up varnish as one service and ensure that the route through from the outside works
Does anyone know of a good resource file for varnish to do this?
What exactly should heartbeat do to varnish when migrated? Usually you start varnish at boot time, and it will wait patiently until it's being put to work because heartbeat moved the ip to that specific machine. Varnish is usually pretty stateless (unlike say, mysql or some clustered filesystem with read-only nodes), and if you only want to start it upon activating a certain cluster node, the LSB scripts should do the trick.