Hi, in JMX each Kafka broker has a value 1 or 0 for ActiveControllerCount. As I understood from this thread, the sum of these values across the cluster should never be something other than 1. The documentation at http://docs.confluent.io/3.1.0/kafka/monitoring.html should be improved to make that clear. Currently it is misleading:
kafka.controller:type=KafkaController,name=ActiveControllerCount Number of active controllers in the cluster. Alert if value is anything other than 1. Suggested: kafka.controller:type=KafkaController,name=ActiveControllerCount Number of active controllers on a broker. Alert if the aggregated sum across all brokers in the cluster is anything other than 1, because in a cluster there should only be one broker with an active controller (cluster singleton). Kind Regards, Sven
