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The behavior of which nodes expose controller metrics will be different in KRaft clusters than the behavior when using Kafka with Zookeeper. KRaft nodes will only expose the controller metrics on the controllers. The controller metrics are calculated as metadata records are replayed e.g. OfflinePartitionCount is calculated as PartitionRecord and PartitionChangeRecord are replayed by the active controller. If the controller is a standby, it will expose 0 for the metric since it has not replayed any metadata records yet. if the node is a "controller" process.

Proposed Changes

Pre-Kraft brokers expose 0 for controller metrics unless they are the active controller. KRaft brokers should not since they are not controller eligible.

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