Kafka scheduler in Vertica 7.2 is running and working, but produce errors - apache-kafka

Question

At the time when I run /opt/vertica/packages/kafka/bin/vkconfig launch I get such warning:
Unable to determine hostname, defaulting to 'unknown' in scheduler history
But the scheduler continues working fine and consuming messages from Kafka. What does it means?
The next strange thing is thet I find next records in /home/dbadmin/events/dbLog (I think it is Kafka consumer log file):
%3|14470569%3|1446726706.945|FAIL|vertica#consumer-1|
localhost:4083/bootstrap: Failed to connect to broker at
[localhost]:4083: Connection refused
%3|1446726706.945|ERROR|vertica#consumer-1| localhost:4083/bootstrap:
Failed to connect to broker at [localhost]:4083: Connection refused
%3|1446726610.267|ERROR|vertica#consumer-1| 1/1 brokers are down
As I mention, the scheduler is finally starting, but this records periodicaly appear in logs. What is this localhost:4083? Normally my broker runs on 9092 port on separate server which is described in kafka_config.kafka_scheduler table.

Answer 1

In the scheduler history table it attempts to get the hostname using Java:
InetAddress.getLocalHost().getHostAddress();
This will sometimes result in an UnknownHostException for various reasons (you can check documentation here: https://docs.oracle.com/javase/7/docs/api/java/net/UnknownHostException.html)
If this occurs, the hostname will default to "unknown" in that table. Luckily, the schedulers work by locking with your Vertica database, so knowing exactly which Scheduler host is unnecessary for functionality (just monitoring).
The Kafka-related logging in dbLog probably is the standard out from rdkafka (https://github.com/edenhill/librdkafka). I'm not sure what is going on with that log message, unfortunately. Vertica should only be using the configured broker list.