apache
KAFKA-17434: Do not test impossible scenarios in upgrade_test.py
Because of KIP-902 (Upgrade Zookeeper version to 3.8.2), it is not possible to upgrade from a Kafka version earlier than 2.4 to a version later than 2.4. Therefore, we should not test these upgrade scenarios in upgrade_test.py. They do happen to work sometimes, but only in the trivial case where we don't create topics or make changes during the upgrade (which would reveal the ZK incompatibility). Instead, we should test only supported scenarios.
Interesting. This is an issue because the ZK cluster provisioned by the system tests is the latest version and not a version that supports the old ZK clients?
Unfortunately, there is no single ZK version that could support both old and new clusters. A version of ZK that worked with Kafka 0.8 would not work with Kafka 3.9.
For versions in between those two extremes, it's messy... there are more details in KIP-902.
@cmccabe KIP-902 has the following:
Zookeeper 3.8.2 server supports clients no older than 3.5.x (i.e. Kafka version 2.4.0) and Zookeeper 3.8.2. clients support server versions no older than 3.5.x (i.e. Kafka version 2.4.0).
Did you mean to allow upgrades from 2.4.0 or greater to the dev branch? The 3.5.x version is referring to the ZK version not the Kafka version.
Yes, I think you're right. It should be AK 2.4 that's the cutoff. not AK 3.5. Will fix.
@cmccabe are you planning to run Confluent's system test job on this branch/pr?
I ran a few variants locally using ducker and it seems good.