As far as I can see we use jmxtrans on druid nodes only for Zookeeper metrics, not for any Druid ones.
JMX Ports are already opened (just updated https://wikitech.wikimedia.org/wiki/Analytics/Systems/Cluster/Ports#JMX) but from druid.io/docs/latest/operations/metrics.html it seems that we'd have two options:
- build a prometheus druid metrics exporter (polling druid's http api periodically)
- export only jmx jvm metrics via jmxtrans or prometheus-jmx-exporter
I'd be in favor of having a complete dashboard with Druid metrics.