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We propose setting the new baseline for protocol API versions to Apache Kafka 2.1 (released 4+ years ago on Nov 2018). More concretely, for each protocol API, we will only keep the most recent version supported by Apache Kafka 2.1 as well as any version introduced after Apache Kafka 2.1. We deviate from the proposed baseline in a few number of cases based on existing clients support. In order to determine client support for the various protocol API versions, we take the latest client release at the end of 2021 - this gives it a better chance of being widely used.

We believe there is merit in having a general protocol API versioning policy that can be applied mechanically on each new major version - we intend to submit a separate KIP for that. It would only apply from Apache Kafka 5.0 to give the ecosystem plenty of time to adapt.

Public Interfaces

Remove support for the following protocol API versions (the range is inclusive):

• Produce: V0-V6
  • librdkafka: V7
  • KafkaJS: V7
  • Sarama: V7
  • kafka-python: V8
• Fetch: V0-V9
  • librdkafka: V11
  • KafkaJS: V11
  • Sarama: V11
  • kafka-python: V11
• ListOffset: V0-V1 due to clients support ((librdkafka, KafkaJS, Sarama) support – V0-V3 per the baseline)
  • librdkafka: V2
  • KafkaJS: V3
  • Sarama: V2
  • kafka-python: V5
• Metadata: V0-V3 due to clients support ((librdkafka, KafkaJS, Sarama, kafka-python) support – V0-V6 per the baseline)
  • librdkafka: V4
  • KafkaJS: V6
  • Sarama: V5
  • kafka-python: V5
• OffsetCommit: V0-V2 due to clients support ((KafkaJS, Sarama, kafka-python) support – V0-V5 per the baseline)
  • librdkafka: V7
  • KafkaJS: V5
  • Sarama: V4
  • kafka-python: V3
• OffsetFetch: V0-V2 due to clients support ((KafkaJS, kafka-python) support – V0-V4 per the baseline)
  • librdkafka: V7
  • KafkaJS: V4
  • Sarama: V7
  • kafka-python: V3
• FindCoordinator: V0 due to clients support ((Sarama, kafka-python) support – V0-V1 per the baseline)
  • librdkafka: V2
  • KafkaJS: V2
  • Sarama: V1
  • kafka-python: V1
• JoinGroup: V0-V1 due to clients (Sarama, kafka-python) support – V0-V2 per the baseline
  • librdkafka: V5
  • KafkaJS: V5
  • Sarama: V2
  • kafka-python: V2
• Heartbeat: none due to clients (Sarama, kafka-python) support – V0-V1 per the baseline
  • librdkafka: V3
  • KafkaJS: V3
  • Sarama: V0
  • kafka-python: V1
• LeaveGroup: V0 none due to clients support ((librdkafka, Sarama, kafka-python) support – V0-V1 per the baseline)
  • librdkafka: V1
  • KafkaJS: V3
  • Sarama: V0
  • kafka-python: V1
• SyncGroup: none due to clients (Sarama) support – V0-V1 per the baseline
  • librdkafka: V3
  • KafkaJS: V3
  • Sarama: V0
  • kafka-python: V2
• DescribeGroups: none due to clients (librdkafka, Sarama) support (– V0-V1 per the baseline)
  • librdkafka: V0
  • KafkaJS: V2
  • Sarama: V0
  • kafka-python: V3
• ListGroups: none due to clients (librdkafka, Sarama) support – V0-V1 per the baseline
  • librdkafka: V0
  • KafkaJS: V2
  • Sarama: V0
  • kafka-python: V2
• SaslHandshake: V0
  • librdkafka: V1
  • KafkaJS: V1
  • Sarama: V1
  • kafka-python: V1
• ApiVersions: V0-V1
  • librdkafka: V3
  • KafkaJS: V2
  • Sarama: V3
  • kafka-python: V2
• CreateTopics: V0-V1 due to clients (Sarama) support – V0-V2 per the baseline
  • librdkafka: V4
  • KafkaJS: V3
  • Sarama: V2
  • kafka-python: V3
• DeleteTopics: V0 due to clients (librdkafka, KafkaJS, Sarama) support – V0-V2 per the baseline
  • librdkafka: V1
  • KafkaJS: V1
  • Sarama: V1
  • kafka-python: V3
• DeleteRecords: none due to clients (Sarama) support – V0 per the baseline
  • librdkafka: V1
  • KafkaJS: V1
  • Sarama: V0
  • kafka-python: none
• InitProducerId: none due to clients (Sarama) support – V0 per the baseline
  • librdkafka: V4
  • KafkaJS: V1
  • Sarama: V0
  • kafka-python: none
• OffsetForLeaderEpoch: V0-V1
  • librdkafka: none
  • KafkaJS: none
  • Sarama: none
  • kafka-python: none
• AddPartitionsToTxn: none due to clients (librdkafka, Sarama) support – V0 per the baseline
  • librdkafka: V0
  • KafkaJS: V1
  • Sarama: V0
  • kafka-python: none
• AddOffsetsToTxn: none due to clients (librdkafka, Sarama) support – V0 per the baseline
  • librdkafka: V0
  • KafkaJS: V1
  • Sarama: V0
  • kafka-python: none
• EndTxn: none due to clients (Sarama) support – V0 per the baseline
  • librdkafka: V1
  • KafkaJS: V1
  • Sarama: V0
  • kafka-python: none
• WriteTxnMarkers: none
• TxnOffsetCommit: none due to clients (KafkaJS, Sarama) support – V0-V1 per the baseline
  • librdkafka: V3
  • KafkaJS: V1
  • Sarama: V0
  • kafka-python: none
• DescribeAcls: V0
  • librdkafka: none
  • KafkaJS: V1
  • Sarama: V1
  • kafka-python: V1
• CreateAcls: V0
  • librdkafka: none
  • KafkaJS: V1
  • Sarama: V1
  • kafka-python: V1
• DeleteAcls: V0
  • librdkafka: none
  • KafkaJS: V1
  • Sarama: V1
  • kafka-python: V1
• DescribeConfigs: V0 due to clients (librdkafka) support – V0-V1 per the baseline
  • librdkafka: V1
  • KafkaJS: V2
  • Sarama: V2
  • kafka-python: V2
• AlterConfigs: none due to clients (librdkafka, Sarama) support – V0 per the baseline
  • librdkafka: V0
  • KafkaJS: V1
  • Sarama: V0
  • kafka-python: V1
• AlterReplicaLogDirs: V0
  • librdkafka: none
  • KafkaJS: none
  • Sarama: none
  • kafka-python: none
• DescribeLogDirs: V0
  • librdkafka: none
  • KafkaJS: none
  • Sarama: V1
  • kafka-python: none
• SaslAuthenticate: None
• CreatePartitions: none due to clients (librdkafka, Sarama) support – V0 per the baseline
  • librdkafka: V0
  • KafkaJS: V1
  • Sarama: V0
  • kafka-python: V1
• CreateDelegationToken: V0
  • librdkafka: none
  • KafkaJS: none
  • Sarama: none
  • kafka-python: none
• RenewDelegationToken: V0
  • librdkafka: none
  • KafkaJS: none
  • Sarama: none
  • kafka-python: none
• ExpireDelegationToken: V0
  • librdkafka: none
  • KafkaJS: none
  • Sarama: none
  • kafka-python: none
• DescribeDelegationToken: V0
  • librdkafka: none
  • KafkaJS: none
  • Sarama: none
  • kafka-python: none
• DeleteGroups: V0
  • librdkafka: V1
  • KafkaJS: V1
  • Sarama: V0
  • kafka-python: V1

Additional information regarding the client releases used for the analysis above:

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