Kafka Connect, Kafka & Strimzi compatibility

[ls-vladyslav-tkachuk]

Hey, I am looking for help to better understand the compatibility and interconnections among the components of Kafka Connect.
For the sake of clarity, I'd like to describe the setup I have and then formulate a question.

So, I have:

• A Kafka Connect cluster running source and sink connectors (image based on strimzi/kafka)
• A separate Kafka cluster (not managed by Strimzi)
• A Strimzi operator running in K8s (manages Kafka Connect connectors and Kafka topics used by the connectors)

What I would like to understand better is the compatible versions of Kafka for a Strimzi operator.
I know that a Strimzi operator version supports certain Kafka versions as mentioned here.
However, I'd like to get whether this refers to both Kafka cluster and Kafka Connect cluster versions or just Kafka Connect cluster (the one hosting the connectors and managed by Strimzi).

Thanks a lot in advance.

[im-konge]

For every version of Strimzi there is list of supported Kafka versions - for Kafka, KafkaConnect, MirrorMaker2 etc.
Those are important for enabling features or some configuration.
In case that you will use Strimzi with some unsupported Kafka version, it's possible that it will simply not work. You have to match the operator version with the supported Kafka version always.

But if you have Kafka cluster managed by something else, you care about the version of Kafka in KafkaConnect (and particular version of Strimzi).

[ls-vladyslav-tkachuk]

Thanks! That's what I wanted to confirm.
And for the Kafka topics managed by Strimzi, I guess if I want to keep the functionality working, I still need to match Strimzi and Kafka version compatibility, right?

[im-konge]

I think that for the management of KafkaTopics it's not a problem if the versions somehow mismatches. TopicOperator will just create the topic in the particular Kafka cluster you specify there. With the components like Connect or MM2 it's important because during the startup Strimzi is adding config (like for logging which changed in 4.0 from log4j to log4j2) that can differ based on the version of Kafka.

[ls-vladyslav-tkachuk]

gotcha, thanks!

[im-konge]

No problem :)