I am running a Kubernetes cluster on Google container engine. My metrics are not getting pushed to Stackdriver by default.
Do I need to start Heapster service explicitly or is it automatically managed by container engine itself?
If there isn't a Heapster pod running in your cluster, then your cluster was created before we started enabling cluster monitoring by default.
We are working on adding a way for users to retroactively turn on monitoring, but if you want metrics pushed into stack driver today you will need to create a new cluster (launching Heapster yourself isn't sufficient for the metrics to get collected).