RabbitMQ 3.8.22

RabbitMQ 3.8.22 is a maintenance release.
All users are recommended to upgrade to this release.

Obtaining Packages

RabbitMQ releases are distributed via GitHub, Cloudsmith,
and PackageCloud.

Erlang/OTP Compatibility Notes

This release requires Erlang 23.2 and supports Erlang 24.

Provisioning Latest Erlang Releases explains
what package repositories and tools can be used to provision modern Erlang versions.

Upgrade and Compatibility Notes

See the Upgrading guide for general documentation on upgrades and
RabbitMQ change log for release notes of other releases.

If upgrading from a3.7.x release, see 3.8.0 release notes
upgrade and compatibility notes first.

If upgrading from a 3.6.x or older release series, first upgrade
to 3.7.27 and then to this version.

Getting Help

Any questions about this release, upgrades or RabbitMQ in general are welcome on the RabbitMQ mailing list
and RabbitMQ community Slack.

Changes Worth Mentioning

Release notes are kept under rabbitmq-server/release-notes.
Contributors are encouraged to update them together with their changes. This helps with release automation and more
consistent release schedule.

Core Server

Bug Fixes

• Virtual host metadata (description, tags) was not imported from definitions.

  GitHub issue: #3333

AWS Peer Discovery Plugin

Enhancements

• AWS API calls are now retried multiple times.

  Contributed by AWS.

  GitHub issue: #3329

Management Plugin

Enhancements

• PUT /api/vhosts/{name} now can update metadata (tags and descriptions) for existing
  virtual hosts.

  GitHub issue: #3319

Dependency Upgrades

No dependency changes in this release.

Source Code Archives

To obtain source code of the entire distribution, please download the archive named rabbitmq-server-3.8.22.tar.xz
instead of the source tarball produced by GitHub.

RabbitMQ 3.9.5

RabbitMQ 3.9.5 is a maintenance release in the 3.9.x release series.

Please refer to the Upgrading to 3.9 section from v3.9.0 release notes if upgrading from a version prior to 3.9.0.

This release requires at least Erlang 23.2, and supports the latest Erlang 24 version, 24.0.5 at the time of release. RabbitMQ and Erlang/OTP Compatibility Matrix has more details on Erlang version requirements for RabbitMQ.

Changes Worth Mentioning

Release notes are kept under rabbitmq-server/release-notes.
Contributors are encouraged to update them together with their changes. This helps with release automation and more
consistent release schedule.

Core Server

Bug Fixes

• Virtual host metadata (description, tags) was not imported from definitions.

  GitHub issue: #3333

• Reduced unnecessary debug logging from streams.

  GitHub issue: #3279

AWS Peer Discovery Plugin

Enhancements

• AWS API calls are now retried multiple times.

  Contributed by AWS.

  GitHub issue: #3329

Management Plugin

Enhancements

• PUT /api/vhosts/{name} now can update metadata (tags and descriptions) for existing
  virtual hosts.

  GitHub issue: #3319

Dependency Upgrades

No dependency changes in this release.

Source Code Archives

To obtain source code of the entire distribution, please download the archive named rabbitmq-server-3.9.5.tar.xz instead of the source tarball produced by GitHub.

RabbitMQ 3.9.4

RabbitMQ 3.9.4 is a maintenance release in the 3.9.x release series.

Please refer to the Upgrading to 3.9 section from v3.9.0 release notes if upgrading from a version prior to 3.9.0.

This release requires at least Erlang 23.2, and supports the latest Erlang 24 version, 24.0.5 at the time of release. RabbitMQ and Erlang/OTP Compatibility Matrix has more details on Erlang version requirements for RabbitMQ.

Changes Worth Mentioning

Release notes are kept under rabbitmq-server/release-notes.
Contributors are encouraged to update them together with their changes. This helps with release automation and more
consistent release schedule.

Core Server

Enhancements

• Nodes will now use four more environment variables, if set: RABBITMQ_DEFAULT_USER (overrides default_user in rabbitmq.conf), RABBITMQ_DEFAULT_PASS (overrides default_pass), RABBITMQ_DEFAULT_VHOST (overrides default_vhost) and RABBITMQ_ERLANG_COOKIE (sets shared authentication secret value).
  These variables are not recommended to be used in production but can be the only realistic option in some environment, such as service containers, ECS, and so on.
  Most users should continue using rabbitmq.conf and a securely generated local cookie file.

  GitHub issue: #3299

• Definitions now can be imported from different sources, including those provided by plugins. Original local filesystem source is still supported in a backwards-compatible way.

  The following rabbitmq.conf example uses a local file as the source:

  # equivalent to the classic load_definitions configuration key   
  definitions.import_backend = local_filesystem
  
  definitions.local.path = /path/to/definitions.json

  This rabbitmq.conf example uses a local directory with definition files:

  # equivalent to the classic load_definitions configuration key   
  definitions.import_backend = local_filesystem
  
  definitions.local.path = /path/to/rabbitmq/definitions.d

  In this example config file, definitions are loaded from a URL accessible over HTTPS:

  # downloads definitions over HTTPS
  definitions.import_backend = https
  
  definitions.https.url = https://rabbitmq.eng.megacorp.local/env-1/definitions.json
  
  # client-side TLS options for definition import   
  definitions.tls.versions.1 = tlsv1.2
  definitions.tls.log_level  = error

  GitHub issue: #3249

Prometheus Plugin

Enhancements

• New Prometheus metrics for alarms:

  • rabbitmq_alarms_file_descriptor_limit 1|0
  • rabbitmq_alarms_free_disk_space_watermark 1|0
  • rabbitmq_alarms_memory_used_watermark 1|0

  While some of the alarms have cluster-wide effect, these metrics are node-local.

  GitHub issue: #2653

Dependency Upgrades

No dependency changes in this release.

Source Code Archives

To obtain source code of the entire distribution, please download the archive named rabbitmq-server-3.9.4.tar.xz instead of the source tarball produced by GitHub.

RabbitMQ 3.9.3

RabbitMQ 3.9.3 is a maintenance release in the 3.9.x release series that addresses a regression introduced in 3.9.0.
All users are recommended to upgrade to this release.

This is what changed since v3.9.2.

Please refer to the Upgrading to 3.9 section from v3.9.0 release notes if you are upgrading from a version prior to 3.9.0.

This release requires at least Erlang 23.2, and supports the latest Erlang 24 version, 24.0.5 at the time of release. RabbitMQ and Erlang/OTP Compatibility Matrix has more details on Erlang version requirements for RabbitMQ.

Changes Worth Mentioning

Release notes are kept under rabbitmq-server/release-notes. Contributors are encouraged to update them together with their changes. This helps with release automation and more consistent release schedule.

Core Server

Bug Fixes

• Queues that had messages with per-message TTL in them could fail to recover their indices after a restart.

  GitHub issues: #3284, #3272

• JSON logging could fail with an exception when a logged event included epoch-based timestamp value.

  GitHub issue: #3281

• JSON logging now uses integers (as opposed to floats) to represent epoch-based timestamps

  GitHub issue: #3282

Enhancements

• RabbitMQ application no longer reports the stopping event to systemd. This was counterproductive when the application was stopped but the runtime (Erlang VM) was kept running, e.g. via rabbitmqctl stop_app or by the pause minority partition handling strategy. Now systemd service monitoring will recognise a node as stopped only when the runtime is stopped, which is usually the behaviour operators expect.

  GitHub issues: #3289, #3280

Dependency Upgrades

No dependency changes in this release.

Source Code Archives

To obtain source code of the entire distribution, please download the archive named rabbitmq-server-3.9.3.tar.xz instead of the source tarball produced by GitHub.

RabbitMQ 3.8.21

RabbitMQ 3.8.21

RabbitMQ 3.8.21 is a maintenance release that addresses a regression introduced in 3.8.17.
All users are recommended to upgrade to this release.

Obtaining Packages

RabbitMQ releases are distributed via GitHub, Cloudsmith,
and PackageCloud.

Erlang/OTP Compatibility Notes

This release requires Erlang 23.2 and supports Erlang 24.

Provisioning Latest Erlang Releases explains
what package repositories and tools can be used to provision modern Erlang versions.

Upgrade and Compatibility Notes

See the Upgrading guide for general documentation on upgrades and
RabbitMQ change log for release notes of other releases.

If upgrading from a3.7.x release, see 3.8.0 release notes
upgrade and compatibility notes first.

If upgrading from a 3.6.x or older release series, first upgrade
to 3.7.27 and then to this version.

Getting Help

Any questions about this release, upgrades or RabbitMQ in general are welcome on the RabbitMQ mailing list
and RabbitMQ community Slack.

Changes Worth Mentioning

Release notes are kept under rabbitmq-server/release-notes.
Contributors are encouraged to update them together with their changes. This helps with release automation and more
consistent release schedule.

Core Server

Bug Fixes

• Queues that had messages with per-message TTL in them could fail to recover their indices
  after a restart.

  GitHub issues: #3284, #3272

Dependency Upgrades

No dependency changes in this release.

Source Code Archives

To obtain source code of the entire distribution, please download the archive named rabbitmq-server-3.8.21.tar.xz
instead of the source tarball produced by GitHub.

RabbitMQ 3.9.2

RabbitMQ 3.9.2 is a maintenance release in the 3.9.x release series. This is what changed since v3.9.1.

Please refer to the Upgrading to 3.9 section from v3.9.0 release notes if you are upgrading from a version prior to 3.9.0.

This release requires at least Erlang 23.2, and supports the latest Erlang 24 version, 24.0.5 at the time of release. RabbitMQ and Erlang/OTP Compatibility Matrix has more details on Erlang version requirements for RabbitMQ.

Changes Worth Mentioning

Release notes are kept under rabbitmq-server/release-notes.
Contributors are encouraged to update them together with their changes. This helps with release automation and more
consistent release schedule.

CLI Tools

Bug Fixes

• rabbitmq-upgrade drain and rabbitmq-upgrade revive now log warning and info level instead of alert.

  GitHub issue: #3266

Shovel Plugin

Bug Fixes

• Multiple Shovels could be started in some cases involving node restarts of failures.

  GitHub issue: #3260

Federation Plugin

Bug Fixes

• Multiple Federation links could be started in some cases involving node restarts of failures.

  GitHub issue: #3260

Dependency Upgrades

• Osiris has been updated to 1.1.0

Source Code Archives

To obtain source code of the entire distribution, please download the archive named rabbitmq-server-3.9.2.tar.xz instead of the source tarball produced by GitHub.

RabbitMQ 3.8.20

RabbitMQ 3.8.20 is a maintenance release in the 3.8.x release series. This is what changed since v3.8.19.

Obtaining Packages

RabbitMQ releases are distributed via GitHub, Cloudsmith, and PackageCloud.

Erlang/OTP Compatibility Notes

This release requires Erlang 23.2 and supports Erlang 24.

Provisioning Latest Erlang Releases explains what package repositories and tools can be used to provision modern Erlang versions.

Upgrade and Compatibility Notes

See the Upgrading guide for general documentation on upgrades and RabbitMQ change log for release notes of other releases.

If upgrading from a3.7.x release, see 3.8.0 release notes upgrade and compatibility notes first.

If upgrading from a 3.6.x or older release series, first upgrade to 3.7.27 and then to this version.

Getting Help

Any questions about this release, upgrades or RabbitMQ in general are welcome on the RabbitMQ mailing list and RabbitMQ community Slack.

Changes Worth Mentioning

Release notes are kept under rabbitmq-server/release-notes. Contributors are encouraged to update them together with their changes. This helps with release automation and more
consistent release schedule.

Core Server

Enhancements

• Nodes failed to start when hostname contained non-ASCII (broader Unicode) characters.

  GitHub issue: #3239

CLI Tools

Bug Fixes

• rabbitmq-upgrade drain and rabbitmq-upgrade revive now log warning and info level instead of alert.

  GitHub issue: #3266

Management Plugin

Bug Fixes

• HTTP API now includes WWW-Authenticate header into 401 responses to requests that contain invalid credentials

  GitHub issue: #3181

• Queue name is now validated for length according to the AMQP 0-9-1 spec.

  GitHub issue: #3202

Shovel Plugin

Bug Fixes

• Multiple Shovels could be started in some cases involving node restart failures.

  GitHub issue: #3263

Federation Plugin

Bug Fixes

• Multiple Federation links could be started in some cases involving node restart failures.

  GitHub issue: #3263

RabbitMQ Erlang Client

Bug Fixes

• New releases of the client are again published to Hex.pm.

  GitHub issue: #3247

• connection_timeout was adjusted to avoid a confusing warning.

  GitHub issue: #3232 contributed by @britto

• Corrected a typo in direct connection net tick time adjustment.

  GitHub issue: #3233 contributed by @britto

Dependency Upgrades

No dependency changes in this release.

Source Code Archives

To obtain source code of the entire distribution, please download the archive named rabbitmq-server-3.8.20.tar.xz instead of the source tarball produced by GitHub.

RabbitMQ 3.9.1

RabbitMQ 3.9.1 is a maintenance release in the 3.9.x release series. This is what changed since v3.9.0.

Please refer to the Upgrading to 3.9 section from v3.9.0 release notes if you are upgrading from a version prior to 3.9.0.

This release requires at least Erlang 23.2, and supports the latest Erlang 24 version, 24.0.5 at the time of release. RabbitMQ and Erlang/OTP Compatibility Matrix has more details on Erlang version requirements for RabbitMQ.

Changes Worth Mentioning

Release notes are kept under rabbitmq-server/release-notes.
Contributors are encouraged to update them together with their changes. This helps with release automation and more
consistent release schedule.

Core Server

Bug Fixes

• Clients that used global QoS prefetch (deprecated as of 3.9.0) ran into an exception when acknowledging deliveries.

  GitHub issue: #3230

• Improved resiliency of stream coordinator in certain conditions.

  GitHub issues: #3176, #3170

• Nodes failed to start when hostname contained non-ASCII (broader Unicode) characters.

  GitHub issue: #3239

CLI Tools

Bug Fixes

• rabbitmq-diagnostics stream_status failed with an exception when the --tracking option was used.

  GitHub issue: #3229

• rabbitmq-diagnostics stream_status used an outdated documentation guide link.

  GitHub issue: #3231

RabbitMQ Erlang Client

Bug Fixes

• New releases of the client are again published to Hex.pm.

  GitHub issue: #3247

• connection_timeout was adjusted to avoid a confusing warning.

  GitHub issue: #3232 contributed by @britto

• Corrected a typo in direct connection net tick time adjustment.

  GitHub issue: #3233 contributed by @britto

RabbitMQ 3.9.0

The most important changes are Streams, support for Erlang 24, and improved integration with our RabbitMQ Kubernetes Operator. Other changes worth mentioning are JSON logging, per-protocol and queue type message rates as Prometheus metrics and faster initial cluster formation on Kubernetes.

Find blog posts that expand on the previously mentioned topics: https://blog.rabbitmq.com/tags/v3.9.x/

Highlights

Streams

Streams are a new persistent and replicated data structure ("queue type") in RabbitMQ which models an append-only log with non-destructive consumer semantics.

They can be used as a regular AMQP 0.9.1 queue or through a new binary protocol plugin and associated client(s).

Streams enable messaging patterns that were not possible or practical before, for example, repeatable non-destructive consumption and mass fanouts to a very large number of consumers.

Erlang 24 Support

Erlang 24 provides 20%-50% higher throughput for many workloads tested by the RabbitMQ core team and community members. Supporting the latest runtime version also allowed RabbitMQ to replace a few external dependencies with libraries now provided by the runtime.

Erlang 24 is now used by default in the community RabbitMQ Docker image.

Kubernetes

RabbitMQ Cluster Operator automates provisioning, management, and operations of RabbitMQ clusters running on Kubernetes. It is open source and is developed by the RabbitMQ Core team at VMware, Inc. This Operator is not specific to 3.9 and can be used with latest 3.8.x release series.

Messaging Topology Operator makes it possible to define RabbitMQ resources (virtual hosts, users, permissions, topologies, policies, etc) as Kubernetes objects. This Operator is also open source and can be used with latest 3.8.x release series.

Logging in JSON

Switch from Lager to the new Erlang Logger API for logging introduces an option for structured logging in JSON. This is relevant for the Prometheus-based alerting feature that we have been investing in this year: Notify me when RabbitMQ has a problem.

Obtaining Packages

RabbitMQ releases are distributed via GitHub, Cloudsmith, and PackageCloud.

Erlang/OTP Compatibility Notes

This release requires Erlang 23.2 or later. Erlang 24 is recommended as it offers 20%-50% throughput improvements for many workloads.

Provisioning Latest Erlang Releases explains what package repositories and tools can be used to provision latest patch versions of Erlang 23.3.x and 24.x.

Upgrading to 3.9

See the Upgrading guide for documentation on upgrades and RabbitMQ change log for release notes of other releases.

RabbitMQ 3.9.0 nodes can run alongside 3.8.x nodes. However, 3.8.16+ as well as 3.9.x both require Erlang 23.2 or later (and support 24). 3.9.x-specific features can only be made available when all nodes in the cluster upgrade to 3.9.0 or any other patch release in the series.

While operating in mixed version mode, some aspects of the system may not behave as expected. The list of known behavior changes is covered below. Once all nodes are upgraded to 3.9.0, these irregularities will go away.

Mixed version clusters are a mechanism that allows rolling upgrade and are not meant to be run for extended periods of time (no more than a few hours).

Quorum Queue Declaration

In a mixed version cluster, declaration of new quorum queues will fail if executed on a node in the version minority. For example, in a five node cluster with two nodes running 3.8, the three 3.9 nodes are in the version majority and the remaining are in the version minority.

Existing quorum queues will operate just like before.

Classic Queue Metrics

HTTP API responses will provide a limited number of metrics or metrics for a limited number of queues (for operations such as GET /api/queues/{vhost}) when operating in mixed version mode.

Compatibility Notes

Client Library Compatibility

Client libraries that were compatible with RabbitMQ 3.8.x will be compatible with 3.9.0.

Upgrading to Erlang 24.x

RabbitMQ 3.8.16 and later require Erlang 23.2 and support Erlang 24 (recommended). Users of RabbitMQ versions that do not support Erlang 23.2 should first upgrade to the latest 3.8.x patch release on Erlang 23.2, then upgrade to 3.9.0, and ideally Erlang 24.

Management API

User tags are now exported as a list, not as a comma-separated list anymore. HTTP API client libraries need some updating to support both types. RabbitMQ 3.9 can import definitions in both formats.

Getting Help

Any questions about this release, upgrades or RabbitMQ in general are welcome on the RabbitMQ mailing list.

Changes Worth Mentioning

Release notes are kept under rabbitmq-server/release-notes.
Contributors are encouraged to update them together with their changes. This helps with release automation and more
consistent release schedule.

Core Server

Enhancements

• Streams, a new durable replicated data structure that allows for repeatable (non-destructive) consumption. RabbitMQ 3.9 introduces a new binary protocol for working with streams. While streams can be used by AMQP 0-9-1 clients, in most cases it will be used via a RabbitMQ stream binary protocol client. The new protocol exposes all the operations specific to this queue type and is heavily optimized for them, resulting in much higher read and write throughput.

  Java and Go clients

• Structural logging in JSON. Nodes can now log in JSON format.

  GitHub issue: #2861

• Peer discovery no longer uses randomized startup delay to ensure only one node starts as a seed one during initial (parallel) cluster formation. Instead it relies on an internal runtime locking library.

  GitHub issue: #3075

• Binding recovery on node startup is now more efficient. This means in clusters with a lot of queues and/or bindings, nodes start quicker.

  GitHub issue: #3137

• Classic mirrored queue replcas are now started synchronously.

  GitHub issue: #2751

• journald notifications are now performed using a library and not an external tool (socat)

  GitHub issue: #2940

• Startup banner now provides more information some of which can be customised.

  GitHub issues: #2247, #2777

• Per-protocol and queue type message rates are now available as Prometheus metrics, as well as Streams-specific errors. This also addresses a long-standing 3.8.x counters issue for most metrics of this type, as captured in #2783.

  GitHub issues: #3127, #3136, #3157

Internal API and Other Changes

• Standard runtime logger is now used for logging instead of Lager, a 3rd party dependency. In modern Erlang versions, the module offers at least a comparable feature set and efficiency of Lager.

  Users who relied on Lager-specific configuration, e.g. custom extensions or sinks, would have to rebuild them on top of the standard Erlang logger module.

  GitHub issue: #2861

• Different Raft-based features now can have different defaults and settings, with more configurability coming at a later point. For example, client ID tracking in the MQTT plugin can use settings for lower memory footprint and more frequent compaction while stream and quorum queues use settings more optimal for higher throughput on the same node.

  GitHub issue: [#2909](#2...

RabbitMQ 3.9.0-rc.2

RabbitMQ 3.9.0-rc.2

RabbitMQ 3.9.0-rc.2 is a candidate of a minor (feature) release. It contains new features, support for Erlang 24, improved integration with our RabbitMQ Kubernetes Operator, and important internal changes in a number of subsystems.

Highlights

Streams

Streams are a new persistent and replicated data structure ("queue type") in RabbitMQ which models an append-only log with non-destructive consumer semantics.

They can be used as a regular AMQP 0.9.1 queue or through a new binary protocol plugin and associated client(s).

Streams enable messaging patterns that were not possible or practical before, for example, repeatable non-destructive consumption and mass fanouts to a very large number of consumers.

Erlang 24 Support

Erlang 24 provides 20%-50% higher throughput for many workloads tested by the RabbitMQ core team and community members.

Erlang 24 is now used by default in the RabbitMQ community Docker image.

Supporting the latest runtime version also allowed RabbitMQ to replace a few external dependencies with libraries now provided by the runtime.

Kubernetes

RabbitMQ Cluster Operator automates provisioning, management, and operations of RabbitMQ clusters running on Kubernetes. It is open source and is developed by the RabbitMQ Core team at VMware, Inc.

This Operator is not specific to 3.9 and can be used with latest 3.8.x release series.

Messaging Topology Operator makes it possible to define RabbitMQ resources (virtual hosts, users, permissions, topologies, policies, etc) as Kubernetes objects. This Operator is also open source and can be used with latest 3.8.x release series.

Logging in JSON

Switch from Lager to the new Erlang Logger API for logging #2861 introduces an option for structured logging in JSON.

Obtaining Packages

RabbitMQ releases are distributed via GitHub, Cloudsmith, and PackageCloud.

Erlang/OTP Compatibility Notes

This release requires Erlang 23.2 or later. Erlang 24 is recommended as it offers 20%-50% throughput improvements for many workloads.

Provisioning Latest Erlang Releases explains what package repositories and tools can be used to provision latest patch versions of Erlang 23.3.x and 24.x.

Upgrading to 3.9

See the Upgrading guide for documentation on upgrades and RabbitMQ change log for release notes of other releases.

RabbitMQ 3.9.0 nodes can run alongside 3.8.x nodes. However, 3.8.16+ as well as 3.9.x both require Erlang 23.2 or later (and support 24). 3.9.x-specific features can only be made available when all nodes in the cluster upgrade to 3.9.0 (or a later 3.9.x release).

While operating in mixed version mode, some aspects of the system may not behave as expected. The list of known behavior changes is covered below. Once all nodes are upgraded to 3.9.0, these irregularities will go away.

Mixed version clusters are a mechanism that allows rolling upgrade and are not meant to be run for longer periods of time.

Quorum Queue Declaration

In a mixed version cluster, declaration of new quorum queues will fail if executed on a node in the version minority. For example, in a five node cluster with two nodes running 3.8, the three 3.9 nodes are in the version majority and the remaining are in the version minority.

Existing quorum queues will operate just like before.

Classic Queue Metrics

HTTP API responses will provide a limited number of metrics or metrics for a limited number of queues (for operations such as GET /api/queues/{vhost}) when operating in mixed version mode.

Compatibility Notes

Client Library Compatibility

Client libraries that were compatible with RabbitMQ 3.8.x will be compatible with 3.9.0.

Upgrading to Erlang 24.x

RabbitMQ 3.8.16 and later require Erlang 23.2 and support Erlang 24. 24 is recommended. Users of versions that do not support Erlang 23.2 should first upgrade to the latest 3.8.x patch release pn Erlang 23.2, then upgrade to 3.9.0 on Erlang 24.

Getting Help

Any questions about this release, upgrades or RabbitMQ in general are welcome on the RabbitMQ mailing list.

Changes Worth Mentioning

Core Server

Enhancements

• Streams, a new durable replicated data structure that allows for repeatable (non-destructive) consumption. RabbitMQ 3.9 introduces a new binary protocol for working with streams. While streams can be used by AMQP 0-9-1 clients, in most cases it will be used via a RabbitMQ stream binary protocol client. The new protocol exposes all the operations specific to this queue type and is heavily optimized for them, resulting in much higher read and write throughput.

  Java and Go clients

• Structural logging in JSON. Nodes can now log in JSON format.

  GitHub issue: #2861

• Peer discovery no longer uses randomized startup delay to ensure only one node starts as a seed one during initial (parallel) cluster formation. Instead it relies on an internal runtime locking library.

  GitHub issue: #3075

• Binding recovery on node startup is now more efficient. This means in clusters with a lot of queues and/or bindings, nodes start quicker.

  GitHub issue: #3137

• Classic mirrored queue replcas are now started synchronously.

  GitHub issue: #2751

• journald notifications are now performed using a library and not an external tool (socat)

  GitHub issue: #2940

• Startup banner now provides more information some of which can be customised.

  GitHub issues: #2247, #2777

• Per-protocol and queue type message rates are now available as Prometheus metrics, as well as Streams-specific errors. This also addresses a long-standing 3.8.x counters issue for most metrics of this type, as captured in #2783.

  GitHub issues: #3127, #3136, #3157

Internal API and Other Changes

• Standard runtime logger is now used for logging instead of Lager, a 3rd party dependency. In modern Erlang versions, the module offers at least a comparable feature set and efficiency of Lager.

  Users who relied on Lager-specific configuration, e.g. custom extensions or sinks, would have to rebuild them on top of the standard Erlang logger module.

  GitHub issue: #2861

• Different Raft-based features now can have different defaults and settings, with more configurability coming at a later point. For example, client ID tracking in the MQTT plugin can use settings for lower memory footprint and more frequent compaction while stream and quorum queues use settings more optimal for higher throughput on the same node.

  GitHub issue: #2909

• Continuous integration of open source RabbitMQ has switched to Bazel, GitHub Actions and BuildBuddy, resulting in much faster and incremental test runs.

  Bazel support for Erlang is a new project open sourced by the RabbitMQ Core team as a result.

• Process group membership now uses pg.

  GitHub issue: #2850

Bug Fixes

• powershell.exe now can run without profile.

  GitHub issue: #2201

• Queue index recovery now can continue after a forced node shutdown during recovery
  (e.g. killed)

  GitHub issue: #3099

• Correct an issue where the num_acceptors.ssl configuration value was applied
  incorrectly

  GitHub issue: #3180

Kubernetes

Enhancements

• [RabbitMQ Cluste...