I have a cluster with a few nodes running druid 0.9.2 (version to be updated soon). When I look a the coordinator web console, I see a calculation about the cluster storage utilization that goes as in the following example:
353 GB free
9 nodes, 116 GB each
1.04 TB total
690 GB (66.2%) used
As a rule of thumb I usually launch a new historical node when the storage utilization is around 80-85% which means that if I could calculate programmatically that value, I’d be able to automate the launch of new nodes as needed. However, after looking at the API exposed by the coordinator node (http://druid.io/docs/0.9.2/design/coordinator.html) I haven’t seen an easy way to do that (loadstatus and loadqueue endpoints look promising, but not exactly what I’m looking for).
Ideally, I should be able to at least write a script that gets that value from the API and add that value to a monitoring solution that can raise an alarm with the value goes over a threshold. Could you let me know what would be the right way to do that?