- Implement Heartbeat API (key 12) for consumer group liveness
- Implement LeaveGroup API (key 13) for graceful consumer departure
- Add comprehensive consumer coordination with state management:
* Heartbeat validation with generation and member checks
* Rebalance state signaling to consumers via heartbeat responses
* Graceful member departure with automatic rebalancing trigger
* Leader election when group leader leaves
* Group state transitions: stable -> rebalancing -> empty
* Subscription topic updates when members leave
- Update ApiVersions to advertise 13 APIs total (was 11)
- Complete test suite with 12 new test cases covering:
* Heartbeat success, rebalance signaling, generation validation
* Member departure, leader changes, empty group handling
* Error conditions (unknown member, wrong generation, invalid group)
* End-to-end coordination workflows
* Request parsing and response building
- All integration tests pass with updated API count (13 APIs)
- E2E tests show '96 bytes' response (increased from 84 bytes)
This completes Phase 3 consumer group implementation, providing full
distributed consumer coordination compatible with Kafka client libraries.
Consumers can now join groups, coordinate partitions, commit offsets,
send heartbeats, and leave gracefully with automatic rebalancing.
- Implement OffsetCommit API (key 8) for consumer offset persistence
- Implement OffsetFetch API (key 9) for consumer offset retrieval
- Add comprehensive offset management with group-level validation
- Integrate offset storage with existing consumer group coordinator
- Support offset retention, metadata, and leader epoch handling
- Add partition assignment validation for offset commits
- Update ApiVersions to advertise 11 APIs total (was 9)
- Complete test suite with 14 new test cases covering:
* Basic offset commit/fetch operations
* Error conditions (invalid group, wrong generation, unknown member)
* End-to-end offset persistence workflows
* Request parsing and response building
- All integration tests pass with updated API count (11 APIs)
- E2E tests show '84 bytes' response (increased from 72 bytes)
This completes consumer offset management, enabling Kafka clients to
reliably track and persist their consumption progress across sessions.
- Implement comprehensive consumer group coordinator with state management
- Add JoinGroup API (key 11) for consumer group membership
- Add SyncGroup API (key 14) for partition assignment coordination
- Create Range and RoundRobin assignment strategies
- Support consumer group lifecycle: Empty -> PreparingRebalance -> CompletingRebalance -> Stable
- Add automatic member cleanup and expired session handling
- Comprehensive test coverage for consumer groups, assignment strategies
- Update ApiVersions to advertise 9 APIs total (was 7)
- All existing integration tests pass with new consumer group support
This provides the foundation for distributed Kafka consumers with automatic
partition rebalancing and group coordination, compatible with standard Kafka clients.
chrislu