mirror of https://github.com/apache/kafka.git
b97a130c08
This change implements upgrading the kraft version from 0 to 1 in existing clusters. Previously, clusters were formatted with either version 0 or version 1, and could not be moved between them. The kraft version for the cluster metadata partition is recorded using the KRaftVersion control record. If there is no KRaftVersion control record the default kraft version is 0. The kraft version is upgraded using the UpdateFeatures RPC. These RPCs are handled by the QuorumController and FeatureControlManager. This change adds special handling in the FeatureControlManager so that upgrades to the kraft.version are directed to RaftClient#upgradeKRaftVersion. To allow the FeatureControlManager to call RaftClient#upgradeKRaftVersion is a non-blocking fashion, the kraft version upgrade uses optimistic locking. The call to RaftClient#upgradeKRaftVersion does validations of the version change. If the validations succeeds, it generates the necessary control records and adds them to the BatchAccumulator. Before the kraft version can be upgraded to version 1, all of the brokers and controllers in the cluster need to support kraft version 1. The check that all brokers support kraft version 1 is done by the FeatureControlManager. The check that all of the controllers support kraft version is done by KafkaRaftClient and LeaderState. When the kraft version is 0, the kraft leader starts by assuming that all voters do not support kraft version 1. The leader discovers which voters support kraft version 1 through the UpdateRaftVoter RPC. The KRaft leader handles UpdateRaftVoter RPCs by storing the updated information in-memory until the kraft version is upgraded to version 1. This state is stored in LeaderState and contains the latest directory id, endpoints and supported kraft version for each voter. Only when the KRaft leader has received an UpdateRaftVoter RPC from all of the voters will it allow the upgrade from kraft.version 0 to 1. Reviewers: Alyssa Huang <ahuang@confluent.io>, Colin P. McCabe <cmccabe@apache.org> |
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