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The CLI tool is versioned. Whenever a Kafka release introduces a new feature version, or modifies an existing feature version, the CLI tool shall will also be updated with this information. Newer versions of the CLI tool will be released as part of the Kafka releases. The tool is handy for both regular usage (upgrade/downgrade all feature max version levels) as well as advanced usage (change specific feature version levels). Later below, we demonstrate both such usages of the CLI tool.

• Regular usage happens typically when after a Kafka release, the cluster operator wants to finalize all latest feature versions. The tool internally has knowledge about a map of features to their respective max versions supported by the Broker. Using this information, the tool provides a facility to upgrade all feature max version levels to latest values known to the tool.
• Downgrade of all feature max version levels, after they are finalized using the tool, are is a rare occurrence. To facilitate emergency downgrade of all feature versions (ex: during just before emergency roll back to a previous Kafka release), the tool provides a downgrade-all facility. To achieve this, the user needs to run the version of the tool packaged with the Kafka release that he/she needs to downgrade to. This is because the tool's knowledge of features and their version values, is limited to the version of the CLI tool itself (i.e. the information is packaged into the CLI tool when it is released).

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