THIS IS A TEST INSTANCE. ALL YOUR CHANGES WILL BE LOST!!!!
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| MBean name | Description |
|---|---|
| kafka.server:type=KafkaServer,name=MetadataType | An enumeration of: ZooKeeper (1) or KRaft (2). Each broker reports this. |
| kafka.controller:type=KafkaController,name=MetadataType | An enumeration of: ZooKeeper (1), KRaft (2), or Dual (3). The active controller reports this. |
| kafka.controller:type=KafkaController,name=Features,feature={feature},level={level} | The finalized set of features with their level as seen by the controller. Used to help operators see the cluster's current metadata.version |
| kafka.controller:type=KafkaController,name=MigrationState | An enumeration of the possible migration states the cluster can be in. This is only reported by the active controller. |
| kafka.controller:type=KafkaController,name=MigrationIneligibleBrokerCount | A count of ZK brokers that are not eligible for migration. This metric will only be reported by the active KRaft controller while in the "MigrationInelgible" MigrationState. If not in that state, it will report zero. |
| kafka.controller:type=KafkaController,name=MigrationIneligibleControllerCount | A count of KRaft quorum controllers that are not eligible for migration. This metric will only be reported by the active KRaft controller while in the "MigrationInelgible" MigrationState. If not in that state, it will report zero. |
| kafka.controller:type=KafkaController,name=ZooKeeperWriteBehindLag | The amount of lag in records that ZooKeeper is behind relative to the highest committed record in the metadata log. This metric will only be reported by the active KRaft controller. |
| kafka.controller:type=KafkaController,name=ZooKeeperBlockingKRaftMillis | The number of milliseconds a write to KRaft has been blocked due to lagging ZooKeeper writes. This metric will only be reported by the active KRaft controller. |
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Here is a state machine description of the migration. There will likely be more internal states that the controller uses, but these four will be exposed as the MigrationState metric.
State | Enum | Description |
| None | 0 | This cluster started out as KRaft and was not migrated. |
MigrationIneligible | 1 | The brokers and controllers do not meet the migration criteria. The cluster is operating in ZooKeeper mode. |
MigratingZkData | 2 | The controller is copying data from ZooKeeper into KRaft. |
DualWriteMetadata | 3 | The controller is in KRaft mode making dual writes to ZooKeeper. |
MigrationFinalized | 4 | The cluster has been migrated to KRaft mode. |
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