Is there a way to find out number of instances of a servicetype that are running in a fabric service cluster at any give time through code? One way is to look at the ApplicationManifest file and get the number of instances set in that, but it might be overwritten sometimes by a parameter file. Any ideas here ?
If you want to examine your services programatically then look at FabricClient which exposes a number of operations that could show you the status deployed services. For your specific question, get the number of running instances, have look at FabricClient.QueryClient.GetReplicaList...(...), it will give you a list of replicas (in the case of StatelessServices, that would be the same as instances).