[KAFKA-14164] Enabling JMX on one Service Breaks kafka-run-class Shell Script for All

• Type: Improvement
• Status: Open
• Priority: Minor
• Resolution: Unresolved
• Affects Version/s: 3.2.1
• Component/s: packaging

Language

shell

• Assignee: Unassigned
• Reporter: Prime Minister of Funhavistan
• Created: 11/Aug/22 21:07
• Updated: 11/Aug/22 21:19

Description

Step 1: On a server running kafka using the kafka-server-start script and KAFKA_JMX_OPTS populated to turn on JMX.  Kafka broker starts with a jmx listener.

Step 2: Use another script like bin/kafka-topics, the shell script always fails because the call to kafka-run-class always triggers starting a jmx listener on the same port in the environment variables.

Expected behavior: Be able to use a script like kafka-topics without error on a host that already has JMX environment variables and a process listening on the defined port.

Actual behavior: bin/kafka-topics errors out trying to start another jmx listener on the same port in KAFKA_JMX_OPTS.

When kafka-topics shell script pass arguments to kafka-run-class, kafka-run-class tries and fails to initialize a jmx listener because, in this example, the kafka-server-start already started one and $JMX_OPTS is always defined/used at the end of kafka-run-class.sh

A proposed solution is editing the kafka-run-class file.

1. add a variable declaration NO_JMX="true"
2. Add the following to the case statement in kafka-run-class.sh kafka.Kafka|org.apache.kafka.connect.cli.ConnectDistributed)
   NO_JMX="false"
   shift;;
3. Add an elif at the end of kafka-run-class.sh 

elif [ "$NO_JMX" = "true" ] ; then
exec "$JAVA" $KAFKA_HEAP_OPTS $KAFKA_JVM_PERFORMANCE_OPTS $KAFKA_GC_LOG_OPTS $KAFKA_LOG4J_OPTS -cp "$CLASSPATH" $KAFKA_OPTS "$@"

The workaround is every time you run a script like kafka-topics.sh or kafka-configs.sh, run it like this JMX_PORT='' KAFKA_JMX_OPTS='' bin/kafka-topics ....