Mirror maker 2 - mirroring topic offset without records

[czandra]

Hello,
I'm mirroring messages in scheme B -> A, Where B (target cluster) is a cluster where my producer is writing messages, and A is a cluster (old source cluster) where my consumer is reading.
Messages mirroring B->A is working, but offset updating A -> B is not.
In addition I have created my own replicationPoicy class, so I'm skipping topic renaming conf on cluster A.
Is there any option to mirror offset without sending messages (A -> B in my schema)?
I think the problem is that there is no topics mapping, but don't know how to deliver such information to checkpoint connector.
That was my original question, where I got an answer here https://github.com/orgs/strimzi/discussions/10146#discussioncomment-12843541
Can you please give me more details, how offset mapping is performed?
Can I configure mm2 in a way that source connector has it's configuration (to create source for offset mapping), but ultimately doesn't send any message?

[katheris]

Hi @czandra,
I'm not fully following what you are trying to achieve with your setup, so I'll explain how the MirrorCheckpointConnector works and hopefully that will clarify things for you. The MirrorCheckpointConnector lists consumer groups on the source cluster and retrieves their committed offsets. Then the connector uses the offset-syncs topic that is created by the MirrorSourceConnector to translate the offsets from the source cluster into their correct value in the target cluster.

So in your scenario you have the MirrorSourceConnector with B as the source, and A as the target.
Then for MirrorCheckpointConnector you have A as the source, and B as the target.

This doesn't make sense, since the point of the MirrorCheckpointConnector is to allow clients who are consuming on a source cluster to fail over to a target cluster. Without the MirrorSourceConnector replicating messages, the MirrorCheckpointConnector has no way to know what the new offsets of those messages would be on the target cluster, and since the messages aren't on the target cluster they can't be consumed anyway.

The MirrorSourceConnector and MirrorCheckpointConnector should have the same source and target clusters configured as each other.