Status

Current state: "Under Discussion

Discussion thread: here

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Make sure the user's code works well when they provide their own slf4j jars

If slf4j-api  is upgraded to 2.0.9, we also provide compatible binding jars for log4j2 logging in Kafka itself. As we introduce this change in major version 4.1.0, it should be ok for users to upgrade their backend dependencies, and we can also provide compatible backend dependencies.

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Please note that users have to upgrade to the matched provider explicitly, and we expect users to be responsible for keeping a consistent version when using other providers.

For future slf4j upgrade: In the future, for slf4j upgrades, we agree not to have a KIP again and follow the same approach mentioned in this KIP.

Test Plan

We have to imitate the user's behavior by manually replacing the dependent log jars and assigning the corresponding environment property.
After that, try to start a Kafka service and see if there is any warning or error. Make sure Kafka still works normally after changing the log framework.

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