2.1.0 (Mar 15, 2025)

Support Kafka Broker 2.1 API Baseline

Add baseline leader_epoch support for ListOffsets v4 / FetchRequest v10 (#2511)
Support OffsetFetch v5 / OffsetCommit v6 (2.1 baseline) (#2505)
Support 2.1 baseline consumer group apis (#2503)
Support FindCoordinatorRequest v2 in consumer and admin client (#2502)
Support ListOffsets v3 in consumer (#2501)
Support Fetch Request/Response v6 in consumer (#2500)
Add support for Metadata Request/Response v7 (#2497)
Implement Incremental Fetch Sessions / KIP-227 (#2508)
Implement client-side connection throttling / KIP-219 (#2510)
Add KafkaClient.api_version(operation) for best available from api_versions (#2495)

Timeout coordinator poll / ensure_coordinator_ready / ensure_active_group (#2526)
Add optional timeout_ms kwarg to remaining consumer/coordinator methods (#2544)
Check for coordinator.poll failure in KafkaConsumer
Only mark coordinator dead if connection_delay > 0 (#2530)
Delay group coordinator until after bootstrap (#2539)
KAFKA-4160: Ensure rebalance listener not called with coordinator lock (#1438)
Call default_offset_commit_callback after _maybe_auto_commit_offsets_async (#2546)
Remove legacy/v1 consumer message iterator (#2543)
Log warning when attempting to list offsets for unknown topic/partition (#2540)
Add heartbeat thread id to debug logs on start
Add inner_timeout_ms handler to fetcher; add fallback (#2529)

KafkaProducer: Flush pending records before close() (#2537)
Raise immediate error on producer.send after close (#2542)
Limit producer close timeout to 1sec in del; use context managers to close in test_producer
Use NullLogger in producer atexit cleanup
Attempt to fix metadata race condition when partitioning in producer.send (#2523)
Remove unused partial KIP-467 implementation (ProduceResponse batch error details) (#2524)

Call ApiVersionsRequest during connection, prior to Sasl Handshake (#2493)
Fake api_versions for old brokers, rename to ApiVersionsRequest, and handle error decoding (#2494)
Debug log when skipping api_versions request with pre-configured api_version
Only refresh metadata if connection fails all dns records (#2532)
Support connections through SOCKS5 proxies (#2531)
Fix OverflowError when connection_max_idle_ms is 0 or inf (#2538)
socket.setblocking for eventlet/gevent compatibility
Support custom per-request timeouts (#2498)
Include request_timeout_ms in request debug log
Support client.poll with future and timeout_ms
mask unused afi var
Debug log if check_version connection attempt fails

Refactor Sasl authentication with SaslMechanism abstract base class; support SaslAuthenticate (#2515)
Add SSPI (Kerberos for Windows) authentication mechanism (#2521)
Support AWS_MSK_IAM authentication (#2519)
Cleanup sasl mechanism configuration checks; fix gssapi bugs; add sasl_kerberos_name config (#2520)
Move kafka.oauth.AbstractTokenProvider -> kafka.sasl.oauth.AbstractTokenProvider (#2525)

Bump default python to 3.13 in CI tests (#2541)
Update pytest log_format: use logger instead of filename; add thread id
Improve test_consumer_group::test_group logging before group stabilized (#2534)
Limit test duration to 5mins w/ pytest-timeout
Fix external kafka/zk fixtures for testing (#2533)
Disable zookeeper admin server to avoid port conflicts
Set default pytest log level to debug
test_group: shorter timeout, more logging, more sleep
Cache servers/dist in github actions workflow (#2527)
Remove tox.ini; update testing docs
Use thread-specific client_id in test_group
Fix subprocess log warning; specify timeout_ms kwarg in consumer.poll tests
Only set KAFKA_JVM_PERFORMANCE_OPTS in makefile if unset; add note re: 2.0-2.3 broker testing
Add kafka command to test.fixtures; raise FileNotFoundError if version not installed