Cluster Failover Scripts

We have just created a cluster of two nodes to host our main web applications using Apache + Php + DRBD. We have configured the cluster and everything seems to be working fine. Now we need to create scripts to auto failover when one of the resources on the server fails or under heavy load. For instance, we need to have a script which will call one webpage which in turn will check database connectivity and access time and if this call fails or takes longer than expected then the cluster service should relocate to the next node.

So has anyone done something similar before?