Thanks Steffen.
By modifying the kafka config to have all lowercase hostnames instead of the uppercase 'A' in there we now get more metrics in ES. We still get the warning the metricbeat log, but I believe that's less important
2016-12-13T14:24:53+01:00 INFO Non-zero metrics in the last 30s: fetches.system-filesystem.success=3 fetches.system-load.events=3 fetches.system-network.success=3 libbeat.es.publish.read_bytes=18480 libbeat.publisher.messages_in_worker_queues=1779 fetches.kafka-partition.success=3 fetches.system-cpu.success=3 fetches.system-memory.success=3 fetches.system-network.events=9 fetches.zookeeper-mntr.success=3 libbeat.es.call_count.PublishEvents=37 libbeat.es.publish.write_bytes=1091865 fetches.system-process.success=3 libbeat.publisher.published_events=1779 fetches.system-cpu.events=3 fetches.zookeeper-mntr.events=3 fetches.system-fsstat.events=3 fetches.system-process.events=1026 fetches.system-load.success=3 libbeat.es.published_and_acked_events=1779 fetches.kafka-partition.events=507 fetches.system-filesystem.events=222 fetches.system-fsstat.success=3 fetches.system-memory.events=3
2016-12-13T14:24:54+01:00 WARN Connected to broker at kfkolaa1.bmt.corp.company.com:9092 (unregistered)
2016-12-13T14:24:54+01:00 WARN Closed connection to broker kfkolaa1.bmt.corp.company.com:9092
Best Regards,
Jo