Configuration updates will not be allowed for the listener used in inter-broker communication. To update inter-broker configs without restarting the broker, a new listener can be created with new configs and the inter-broker listener can be changed to the new listener (similar to the currently documented security upgrade process).

Future Work

Message Format and Inter Broker Protocol

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AdminClient needs to verify that all brokers in the cluster support the new version before making an update. To enable this, the version of the broker will be added to the JSON registered by each broker during startup at /brokers/ids/id. To avoid all brokers reading version information from ZooKeeper, the controller should propagate this information in UpdateMetadataRequest. This requires protocol change. Note also that this approach only allows verification of the version of brokers that are alive at the time AlterConfigs is executed.

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