external database jdbc url when using a postgres master-slave cluster

Hi

I have read the document here Scaling for the Information Explosion: Master-Slave Cluster with vFabric Postgres 9.2 on vSphere | VMware vFabric Blog -… and the document that details how to setup workspace to use an external postgres DB but it is missing some config info when using a master-slave cluster

When i have set up the cluster should the jdbc url point to the master host? If the cluster fails over how does Workspace know to point at the secondary host? It doesnt appear that there is a dedicated cluster IP/hostname i can point to?

Or do i need to create a DNS CNAME that points to the master and change that manually in a failover event?

Thanks