librdkafka v2.12.1 is a maintenance release:

• Restored macOS binaries compatibility with macOS 13 and 14 (#5219).

Fixes

General fixes

• Fix to restore macOS 13 and 14 compatibility in prebuilt binaries present in librdkafka.redist.
  Happening since 2.12.0 (#5219).

Checksums

Release asset checksums:

• v2.12.1.zip SHA256 da7571a0c1dc374aabb18af6ca01411d4bc597d321977980c8d3211ec5adf696
• v2.12.1.tar.gz SHA256 ec103fa05cb0f251e375f6ea0b6112cfc9d0acd977dc5b69fdc54242ba38a16f

librdkafka v2.12.0 is a feature release:

KIP-848 – General Availability

Starting with librdkafka 2.12.0, the next generation consumer group rebalance protocol defined in KIP-848 is production-ready. Please refer the following migration guide for moving from classic to consumer protocol.

Note: The new consumer group protocol defined in KIP-848 is not enabled by default. There are few contract change associated with the new protocol and might cause breaking changes. group.protocol configuration property dictates whether to use the new consumer protocol or older classic protocol. It defaults to classic if not provided.

Enhancements and Fixes

• Support for OAUTHBEARER metadata based authentication types,
  starting with Azure IMDS. Introduction available (#5155).
• Fix compression types read issue in GetTelemetrySubscriptions response
  for big-endian architectures (#5183, @paravoid).
• Fix for KIP-1102 time based re-bootstrap condition (#5177).
• Fix for discarding the member epoch in a consumer group heartbeat response when leaving with an inflight HB (#4672).
• Fix for an error being raised after a commit due to an existing error in the topic partition (#4672).
• Fix double free of headers in rd_kafka_produceva method (@blindspotbounty, #4628).
• Fix to ensure rd_kafka_query_watermark_offsets enforces the specified timeout and does not continue beyond timeout expiry (#5201).
• New walkthrough in the Wiki about configuring Kafka cross-realm authentication between Windows SSPI and MIT Kerberos.

Fixes

General fixes

• Issues: #5178.
  Fix for KIP-1102 time based re-bootstrap condition.
  Re-bootstrap is now triggered only after metadata.recovery.rebootstrap.trigger.ms
  have passed since first metadata refresh request after last successful
  metadata response. The calculation was since last successful metadata response
  so it's possible it did overlap with the periodic topic.metadata.refresh.interval.ms
  and cause a re-bootstrap even if not needed.
  Happening since 2.11.0 (#5177).
• Issues: #4878.
  Fix to ensure rd_kafka_query_watermark_offsets enforces the specified timeout and does not continue beyond timeout expiry.
  Happening since 2.3.0 (#5201).

Telemetry fixes

• Issues: #5179 .
  Fix issue in GetTelemetrySubscriptions with big-endian
  architectures where wrong values are read as
  accepted compression types causing the metrics to be sent uncompressed.
  Happening since 2.5.0. Since 2.10.1 unit tests are failing when run on
  big-endian architectures (#5183, @paravoid).

Consumer fixes

• Issues: #5199
  Fixed an issue where topic partition errors were not cleared after a successful
  commit. Previously, a partition could retain a stale error state even though the
  most recent commit succeeded, causing misleading error reporting. Now, successful
  commits correctly clear the error state for the affected partitions
  Happening since 2.4.0 (#4672).

Producer fixes

• Issues: #4627.
  Fix double free of headers in rd_kafka_produceva method in cases where the partition doesn't exist.
  Happening since 1.x (@blindspotbounty, #4628).

Checksums

Release asset checksums:

• v2.12.0.zip SHA256 9b2f373e03f3d5d87c2075b3ce07ee9ea3802eea00cea41b99d8351a68d8a062
• v2.12.0.tar.gz SHA256 1355d81091d13643aed140ba0fe62437c02d9434b44e90975aaefab84c2bf237

librdkafka v2.11.1 is a maintenance release:

• Made the conditions for enabling the features future proof (#5130).
• Avoid returning an all brokers down error on planned disconnections (#5126).
• An "all brokers down" error isn't returned when we haven't tried to connect
  to all brokers since last successful connection (#5126).

Fixes

General fixes

• Issues: #4948, #4956.
  Made the conditions for enabling the features future proof, allowing to
  remove RPC versions in a subsequent Apache Kafka version without disabling
  features. The existing checks were matching a single version instead of
  a range and were failing if the older version was removed.
  Happening since 1.x (#5130).

• Issues: #5142.
  Avoid returning an all brokers down error on planned disconnections.
  This is done by avoiding to count planned disconnections, such as idle
  disconnections, broker host change and similar as events that can cause
  the client to reach the "all brokers down" state, returning an error and
  since 2.10.0 possibly starting a re-bootstrap sequence.
  Happening since 1.x (#5126).

• Issues: #5142.
  An "all brokers down" error isn't returned when we haven't tried to connect
  to all brokers since last successful connection. It happened because the down
  state is cached and can be stale when a connection isn't needed to that
  particular broker. Solved by resetting the cached broker down state when any
  broker successfully connects, so that broker needs to be tried again.
  Happening since 1.x (#5126).

Checksums

Release asset checksums:

• v2.11.1.zip SHA256 4a63e4422e5f5bbbb47f0ac1200e2ebd1f91b7b23f0de1bc625810c943fb870e
• v2.11.1.tar.gz SHA256 a2c87186b081e2705bb7d5338d5a01bc88d43273619b372ccb7bb0d264d0ca9f

librdkafka v2.11.0 is a feature release:

• KIP-1102 Enable clients to rebootstrap based on timeout or error code (#4981).
• KIP-1139 Add support for OAuth jwt-bearer grant type (#4978).
• Fix for poll ratio calculation in case the queues are forwarded (#5017).
• Fix data race when buffer queues are being reset instead of being
  initialized (#4718).
• Features BROKER_BALANCED_CONSUMER and SASL_GSSAPI don't depend on
  JoinGroup v0 anymore, missing in AK 4.0 and CP 8.0 (#5131).
• Improve HTTPS CA certificates configuration by probing several paths
  when OpenSSL is statically linked and providing a way to customize their location
  or value (#5133).

Fixes

General fixes

• Issues: #4522.
  A data race happened when emptying buffers of a failing broker, in its thread,
  with the statistics callback in main thread gathering the buffer counts.
  Solved by resetting the atomic counters instead of initializing them.
  Happening since 1.x (#4718).
• Issues: #4948
  Features BROKER_BALANCED_CONSUMER and SASL_GSSAPI don't depend on
  JoinGroup v0 anymore, missing in AK 4.0 and CP 8.0. This PR partially
  fixes the linked issue, a complete fix for all features will follow.
  Rest of fixes are necessary only for a subsequent Apache Kafka major
  version (e.g. AK 5.x).
  Happening since 1.x (#5131).

Telemetry fixes

• Issues: #5109
  Fix for poll ratio calculation in case the queues are forwarded.
  Poll ratio is now calculated per-queue instead of per-instance and
  it allows to avoid calculation problems linked to using the same
  field.
  Happens since 2.6.0 (#5017).

Checksums

Release asset checksums:

• v2.11.0.zip SHA256 9e76a408f0ed346f21be5e2df58b672d07ff9c561a5027f16780d1b26ef24683
• v2.11.0.tar.gz SHA256 592a823dc7c09ad4ded1bc8f700da6d4e0c88ffaf267815c6f25e7450b9395ca

librdkafka v2.10.1 is a maintenance release:

• Fix to add locks when updating the metadata cache for the consumer
  after no broker connection is available (@marcin-krystianc, #5066).
• Fix to the re-bootstrap case when bootstrap.servers is NULL and
  brokers were added manually through rd_kafka_brokers_add (#5067).
• Fix an issue where the first message to any topic produced via producev or
  produceva was delivered late (by up to 1 second) (#5032).
• Fix for a loop of re-bootstrap sequences in case the client reaches the
  all brokers down state (#5086).
• Fix for frequent disconnections on push telemetry requests
  with particular metric configurations (#4912).
• Avoid copy outside boundaries when reading metric names in telemetry
  subscription (#5105)
• Metrics aren't duplicated when multiple prefixes match them (#5104)

Fixes

General fixes

• Issues: #5088.
  Fix for a loop of re-bootstrap sequences in case the client reaches the
  all brokers down state. The client continues to select the
  bootstrap brokers given they have no connection attempt and doesn't
  re-connect to the learned ones. In case it happens a broker restart
  can break the loop for the clients using the affected version.
  Fixed by giving a higher chance to connect to the learned brokers
  even if there are new ones that never tried to connect.
  Happens since 2.10.0 (#5086).
• Issues: #5057.
  Fix to the re-bootstrap case when bootstrap.servers is NULL and
  brokers were added manually through rd_kafka_brokers_add.
  Avoids a segmentation fault in this case.
  Happens since 2.10.0 (#5067).

Producer fixes

• In case of producev or produceva, the producer did not enqueue a leader
  query metadata request immediately, and rather, waited for the 1 second
  timer to kick in. This could cause delays in the sending of the first message
  by up to 1 second.
  Happens since 1.x (#5032).

Consumer fixes

• Issues: #5051.
  Fix to add locks when updating the metadata cache for the consumer.
  It can cause memory corruption or use-after-free in case
  there's no broker connection and the consumer
  group metadata needs to be updated.
  Happens since 2.10.0 (#5066).

Telemetry fixes

• Issues: #5106.
  Fix for frequent disconnections on push telemetry requests
  with particular metric configurations.
  A NULL payload is sent in a push telemetry request when
  an empty one is needed. This causes disconnections every time the
  push is sent, only when metrics are requested and
  some metrics are matching the producer but none the consumer
  or the other way around.
  Happens since 2.5.0 (#4912).
• Issues: #5102.
  Avoid copy outside boundaries when reading metric names in telemetry
  subscription. It can cause that some metrics aren't matched.
  Happens since 2.5.0 (#5105).
• Issues: #5103.
  Telemetry metrics aren't duplicated when multiple prefixes match them.
  Fixed by keeping track of the metrics that already matched.
  Happens since 2.5.0 (#5104).

Checksums

Release asset checksums:

• v2.10.1.zip SHA256 7cb72c4f3d162f50d30d81fd7f7ba0f3d9e8ecd09d9b4c5af7933314e24dd0ba
• v2.10.1.tar.gz SHA256 75f59a2d948276504afb25bcb5713a943785a413b84f9099d324d26b2021f758

librdkafka v2.10.0 is a feature release:

KIP-848 – Now in Preview

• KIP-848 has transitioned from Early Access to Preview.
• Added support for regex-based subscriptions.
• Implemented client-side member ID generation as per KIP-1082.
• rd_kafka_DescribeConsumerGroups() now supports KIP-848-style consumer groups. Two new fields have been added:
  • Group type – Indicates whether the group is classic or consumer.
  • Target assignment – Applicable only to consumer protocol groups (defaults to NULL).
• Group configuration is now supported in AlterConfigs, IncrementalAlterConfigs, and DescribeConfigs. (#4939)
• Added Topic Authorization Error support in the ConsumerGroupHeartbeat response.
• Removed usage of the partition.assignment.strategy property for the consumer group protocol. An error will be raised if this is set with group.protocol=consumer.
• Deprecated and disallowed the following properties for the consumer group protocol:
  • session.timeout.ms
  • heartbeat.interval.ms
  • group.protocol.type
    Attempting to set any of these will result in an error.
• Enhanced handling for subscribe() and unsubscribe() edge cases.

Enhancements and Fixes

• Identify brokers only by broker id (#4557, @mfleming)
• Remove unavailable brokers and their thread (#4557, @mfleming)
• Commits during a cooperative incremental rebalance aren't causing
  an assignment lost if the generation id was bumped in between (#4908).
• Fix for librdkafka yielding before timeouts had been reached (#4970)
• Removed a 500ms latency when a consumer partition switches to a different
  leader (#4970)
• The mock cluster implementation removes brokers from Metadata response
  when they're not available, this simulates better the actual behavior of
  a cluster that is using KRaft (#4970).
• Doesn't remove topics from cache on temporary Metadata errors but only
  on metadata cache expiry (#4970).
• Doesn't mark the topic as unknown if it had been marked as existent earlier
  and topic.metadata.propagation.max.ms hasn't passed still (@marcin-krystianc, #4970).
• Doesn't update partition leaders if the topic in metadata
  response has errors (#4970).
• Only topic authorization errors in a metadata response are considered
  permanent and are returned to the user (#4970).
• The function rd_kafka_offsets_for_times refreshes leader information
  if the error requires it, allowing it to succeed on
  subsequent manual retries (#4970).
• Deprecated api.version.request, api.version.fallback.ms and
  broker.version.fallback configuration properties (#4970).
• When consumer is closed before destroying the client, the operations queue
  isn't purged anymore as it contains operations
  unrelated to the consumer group (#4970).
• When making multiple changes to the consumer subscription in a short time,
  no unknown topic error is returned for topics that are in the new subscription but weren't in previous one (#4970).
• Prevent metadata cache corruption when topic id changes
  (@kwdubuc, @marcin-krystianc, @GerKr, #4970).
• Fix for the case where a metadata refresh enqueued on an unreachable broker
  prevents refreshing the controller or the coordinator until that broker
  becomes reachable again (#4970).
• Remove a one second wait after a partition fetch is restarted following a
  leader change and offset validation (#4970).
• Fix the Nagle algorithm (TCP_NODELAY) on broker sockets to not be enabled
  by default (#4986).

Fixes

General fixes

• Issues: #4212
  Identify brokers only by broker id, as happens in Java,
  avoid to find the broker with same hostname and use the same thread
  and connection.
  Happens since 1.x (#4557, @mfleming).
• Issues: #4557
  Remove brokers not reported in a metadata call, along with their thread.
  Avoids that unavailable brokers are selected for a new connection when
  there's no one available. We cannot tell if a broker was removed
  temporarily or permanently so we always remove it and it'll be added back when
  it becomes available again.
  Happens since 1.x (#4557, @mfleming).
• Issues: #4970
  librdkafka code using cnd_timedwait was yielding before a timeout occurred
  without the condition being fulfilled because of spurious wake-ups.
  Solved by verifying with a monotonic clock that the expected point in time
  was reached and calling the function again if needed.
  Happens since 1.x (#4970).
• Issues: #4970
  Doesn't remove topics from cache on temporary Metadata errors but only
  on metadata cache expiry. It allows the client to continue working
  in case of temporary problems to the Kafka metadata plane.
  Happens since 1.x (#4970).
• Issues: #4970
  Doesn't mark the topic as unknown if it had been marked as existent earlier
  and topic.metadata.propagation.max.ms hasn't passed still. It achieves
  this property expected effect even if a different broker had
  previously reported the topic as existent.
  Happens since 1.x (@marcin-krystianc, #4970).
• Issues: #4907
  Doesn't update partition leaders if the topic in metadata
  response has errors. It's in line with what Java client does and allows
  to avoid segmentation faults for unknown partitions.
  Happens since 1.x (#4970).
• Issues: #4970
  Only topic authorization errors in a metadata response are considered
  permanent and are returned to the user. It's in line with what Java client
  does and avoids returning to the user an error that wasn't meant to be
  permanent.
  Happens since 1.x (#4970).
• Issues: #4964, #4778
  Prevent metadata cache corruption when topic id for the same topic name
  changes. Solved by correctly removing the entry with the old topic id from metadata cache
  to prevent subsequent use-after-free.
  Happens since 2.4.0 (@kwdubuc, @marcin-krystianc, @GerKr, #4970).
• Issues: #4970
  Fix for the case where a metadata refresh enqueued on an unreachable broker
  prevents refreshing the controller or the coordinator until that broker
  becomes reachable again. Given the request continues to be retried on that
  broker, the counter for refreshing complete broker metadata doesn't reach
  zero and prevents the client from obtaining the new controller or group or transactional coordinator.
  It causes a series of debug messages like:
  "Skipping metadata request: ... full request already in-transit", until
  the broker the request is enqueued on is up again.
  Solved by not retrying these kinds of metadata requests.
  Happens since 1.x (#4970).
• The Nagle algorithm (TCP_NODELAY) is now disabled by default. It caused a
  large increase in latency for some use cases, for example, when using an
  SSL connection.
  For efficient batching, the application should use linger.ms,
  batch.size etc.
  Happens since: 0.x (#4986).

Consumer fixes

• Issues: #4059
  Commits during a cooperative incremental rebalance could cause an
  assignment lost if the generation id was bumped by a second join
  group request.
  Solved by not rejoining the group in case an illegal generation error happens
  during a rebalance.
  Happening since v1.6.0 (#4908)
• Issues: #4970
  When switching to a different leader a consumer could wait 500ms
  (fetch.error.backoff.ms) before starting to fetch again. The fetch backoff wasn't reset when joining the new broker.
  Solved by resetting it, given it's not needed to backoff
  the first fetch on a different node. This way faster leader switches are
  possible.
  Happens since 1.x (#4970).
• Issues: #4970
  The function rd_kafka_offsets_for_times refreshes leader information
  if the error requires it, allowing it to succeed on
  subsequent manual retries. Similar to the fix done in 2.3.0 in
  rd_kafka_query_watermark_offsets. Additionally, the partition
  current leader epoch is taken from metadata cache instead of
  from passed partitions.
  Happens since 1.x (#4970).
• Issues: #4970
  When consumer is closed before destroying the client, the operations queue
  isn't purged anymore as it contains operations
  unrelated to the consumer group.
  Happens since 1.x (#4970).
• Issues: #4970
  When making multiple changes to the consumer subscription in a short time,
  no unknown topic error is returned for topics that are in the new subscription
  but weren't in previous one. This was due to the metadata request relative
  to previous subscription.
  Happens since 1.x (#4970).
• Issues: #4970
  Remove a one second wait after a partition fetch is restarted following a
  leader change and offset validation. This is done by resetting the fetch
  error backoff and waking up the delegated broker if present.
  Happens since 2.1.0 (#4970).

Note: there was no v2.9.0 librdkafka release,
it was a dependent clients release only

Checksums

Release asset checksums:

• v2.10.0.zip SHA256 e30944f39b353ee06e70861348011abfc32d9ab6ac850225b0666e9d97b9090d
• v2.10.0.tar.gz ...

librdkafka v2.8.0 is a maintenance release:

• Socket options are now all set before connection (#4893).
• Client certificate chain is now sent when using ssl.certificate.pem
  or ssl_certificate or ssl.keystore.location (#4894).
• Avoid sending client certificates whose chain doesn't match with broker
  trusted root certificates (#4900).
• Fixes to allow to migrate partitions to leaders with same leader epoch,
  or NULL leader epoch (#4901).
• Support versions of OpenSSL without the ENGINE component (Chris Novakovic, #3535
  and @remicollet, #4911).

Fixes

General fixes

• Socket options are now all set before connection, as documentation
  says it's needed for socket buffers to take effect, even if in some
  cases they could have effect even after connection.
  Happening since v0.9.0 (#4893).
• Issues: #3225.
  Client certificate chain is now sent when using ssl.certificate.pem
  or ssl_certificate or ssl.keystore.location.
  Without that, broker must explicitly add any intermediate certification
  authority certificate to its truststore to be able to accept client
  certificate.
  Happens since: 1.x (#4894).

Consumer fixes

• Issues: #4796.
  Fix to allow to migrate partitions to leaders with NULL leader epoch.
  NULL leader epoch can happen during a cluster roll with an upgrade to a
  version supporting KIP-320.
  Happening since v2.1.0 (#4901).
• Issues: #4804.
  Fix to allow to migrate partitions to leaders with same leader epoch.
  Same leader epoch can happen when partition is
  temporarily migrated to the internal broker (#4804), or if broker implementation
  never bumps it, as it's not needed to validate the offsets.
  Happening since v2.4.0 (#4901).

Note: there was no v2.7.0 librdkafka release

Checksums

Release asset checksums:

• v2.8.0.zip SHA256 5525efaad154e277e6ce30ab78bb00dbd882b5eeda6c69c9eeee69b7abee11a4
• v2.8.0.tar.gz SHA256 5bd1c46f63265f31c6bfcedcde78703f77d28238eadf23821c2b43fc30be3e25

Note: given this patch version contains only a single fix, it's suggested to upgrade to latest backward compatible release instead, as it contains all the issued fixes.
Following semver 2.0, all our patch and minor releases are backward compatible and our minor releases may also contain fixes.
Please note that 2.x versions of librdkafka are also backward compatible with 1.x as the major version release was only for the upgrade to OpenSSL 3.x.

librdkafka v2.2.1 is a maintenance release backporting:

• Fix for idempotent producer fatal errors, triggered after a possibly persisted message state (#4438).
• Update bundled lz4 (used when ./configure --disable-lz4-ext) to
  v1.9.4, which contains
  bugfixes and performance improvements (#4726).
• Upgrade OpenSSL to v3.0.13 (while building from source) with various security fixes,
  check the release notes
  (@janjwerner-confluent, #4690).
• Upgrade zstd to v1.5.6, zlib to v1.3.1, and curl to v8.8.0 (@janjwerner-confluent, #4690).
• Upgrade Linux dependencies: OpenSSL 3.0.15, CURL 8.10.1 (#4875).

Checksums

Release asset checksums:

• v2.2.1.zip SHA256 2d7fdb54b17be8442b61649916b94eda1744c21d2325795d92f9ad6dec4e5621
• v2.2.1.tar.gz SHA256 c6f0ccea730ce8f67333e75cc785cce28a8941d5abf041d7a9b8fef91d4778e8

librdkafka v2.6.1 is a maintenance release:

• Fix for a Fetch regression when connecting to Apache Kafka < 2.7 (#4871).
• Fix for an infinite loop happening with cooperative-sticky assignor
  under some particular conditions (#4800).
• Fix for retrieving offset commit metadata when it contains
  zeros and configured with strndup (#4876)
• Fix for a loop of ListOffset requests, happening in a Fetch From Follower
  scenario, if such request is made to the follower (#4616, #4754, @kphelps).
• Fix to remove fetch queue messages that blocked the destroy of rdkafka
  instances (#4724)
• Upgrade Linux dependencies: OpenSSL 3.0.15, CURL 8.10.1 (#4875).
• Upgrade Windows dependencies: MSVC runtime to 14.40.338160.0,
  zstd 1.5.6, zlib 1.3.1, OpenSSL 3.3.2, CURL 8.10.1 (#4872).
• SASL/SCRAM authentication fix: avoid concatenating
  client side nonce once more, as it's already prepended in server sent nonce (#4895).
• Allow retrying for status code 429 ('Too Many Requests') in HTTP requests for
  OAUTHBEARER OIDC (#4902).

Fixes

General fixes

• SASL/SCRAM authentication fix: avoid concatenating
  client side nonce once more, as it's already prepended in
  server sent nonce.
  librdkafka was incorrectly concatenating the client side nonce again, leading to this fix being made on AK side, released with 3.8.1, with endsWith instead of equals.
  Happening since v0.0.99 (#4895).

Consumer fixes

• Issues: #4870
  Fix for a Fetch regression when connecting to Apache Kafka < 2.7, causing
  fetches to fail.
  Happening since v2.6.0 (#4871)
• Issues: #4783.
  A consumer configured with the cooperative-sticky partition assignment
  strategy could get stuck in an infinite loop, with corresponding spike of
  main thread CPU usage.
  That happened with some particular orders of members and potential
  assignable partitions.
  Solved by removing the infinite loop cause.
  Happening since: 1.6.0 (#4800).
• Issues: #4649.
  When retrieving offset metadata, if the binary value contained zeros
  and librdkafka was configured with strndup, part of
  the buffer after first zero contained uninitialized data
  instead of rest of metadata. Solved by avoiding to use
  strndup for copying metadata.
  Happening since: 0.9.0 (#4876).
• Issues: #4616
  When an out of range on a follower caused an offset reset, the corresponding
  ListOffsets request is made to the follower, causing a repeated
  "Not leader for partition" error. Fixed by sending the request always
  to the leader.
  Happening since 1.5.0 (tested version) or previous ones (#4616, #4754, @kphelps).
• Issues:
  Fix to remove fetch queue messages that blocked the destroy of rdkafka
  instances. Circular dependencies from a partition fetch queue message to
  the same partition blocked the destroy of an instance, that happened
  in case the partition was removed from the cluster while it was being
  consumed. Solved by purging internal partition queue, after being stopped
  and removed, to allow reference count to reach zero and trigger a destroy.
  Happening since 2.0.2 (#4724).

Checksums

Release asset checksums:

• v2.6.1.zip SHA256 b575811865d9c0439040ccb2972ae6af963bc58ca39d433243900dddfdda79cf
• v2.6.1.tar.gz SHA256 0ddf205ad8d36af0bc72a2fec20639ea02e1d583e353163bf7f4683d949e901b

librdkafka v2.6.0 is a feature release:

• KIP-460 Admin Leader Election RPC (#4845)
• [KIP-714] Complete consumer metrics support (#4808).
• [KIP-714] Produce latency average and maximum metrics support for parity with Java client (#4847).
• [KIP-848] ListConsumerGroups Admin API now has an optional filter to return only groups
  of given types.
• Added Transactional id resource type for ACL operations (@JohnPreston, #4856).
• Fix for permanent fetch errors when using a newer Fetch RPC version with an older
  inter broker protocol (#4806).

Fixes

Consumer fixes

• Issues: #4806
  Fix for permanent fetch errors when brokers support a Fetch RPC version greater than 12
  but cluster is configured to use an inter broker protocol that is less than 2.8.
  In this case returned topic ids are zero valued and Fetch has to fall back
  to version 12, using topic names.
  Happening since v2.5.0 (#4806)

Checksums

Release asset checksums:

• v2.6.0.zip SHA256 e9eb7faedb24da3a19d5f056e08630fc2dae112d958f9b714ec6e35cd87c032e
• v2.6.0.tar.gz SHA256 abe0212ecd3e7ed3c4818a4f2baf7bf916e845e902bb15ae48834ca2d36ac745