Minor refactor in start script to remove Kafka-related leftovers

[danielgospodinow]

What

CC's start script defines variables with a KAFKA_ prefix which is incorrect. This is likely a leftover from copy-pasting Kafka start scripts. 😁

Looking at kafka-run-class.sh and kafka-server-start.sh further supports my claim. Lol.

Why

Might cause a confusion when reading the code, especially to an engineer that's new to the codebase.

Categorization

• documentation
• bugfix
• new feature
• refactor
• security/CVE
• other

[danielgospodinow]

This is the only line I've removed given that kafka.logs.dir is not part of Cruise Control. Everything else is just renaming.

[kyguy]

+1

[kyguy]

CircleCI failures are unrelated to the changes in this PR, they are due to some flaky tests which should be resolved by #2338.

[mimaison]

This is a major operational change for anyone using Cruise Control. I expect a (large?) portion of users set some of these environment variables to tune Cruise Control and this is going to break their environments.

I can understand the desire to move away from Kafka names but it should be done in a compatible manner to give time for people to migrate.

I also wonder if names prefixed with something like CC_ would be better than the names used i this PR.

[danielgospodinow]

I expect a (large?) portion of users set some of these environment variables to tune Cruise Control and this is going to break their environments.

True. Yet I think it's the right thing to do since the current names are confusing if you operate both CC and Kafka (which obviously is quite common), and it's anyway a simple change to adopt if something breaks.

I also wonder if names prefixed with something like CC_ would be better than the names used i this PR.

Sure, I'm fine with this suggestion too.

[Copilot]

Pull request overview

This PR refactors kafka-cruise-control-start.sh to remove Kafka-prefixed environment variables (KAFKA_*) that were likely copy/pasted leftovers, making the script’s configuration surface less confusing for Cruise Control users.

Changes:

• Renames several KAFKA_* env vars (e.g., KAFKA_OPTS, KAFKA_HEAP_OPTS, KAFKA_JMX_OPTS) to more generic equivalents (JVM_OPTS, HEAP_OPTS, JMX_OPTS, etc.).
• Updates the Java launch command to use the renamed variables.
• Removes some Kafka-specific log option wiring.

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