Merge pull request #7519 from rabbitmq/mergify/bp/v3.12.x/pr-7518

Initial 3.12 release notes (backport #7518)

Author: michaelklishin

release-notes/3.11.0.md

@@ -4,7 +4,7 @@ RabbitMQ 3.11 is a new feature release.
 
 ## Highlights
 
-This release includes several new featues and optimizations, graduates (makes mandatory) a number of feature flags,
+This release includes several new features and optimizations, graduates (makes mandatory) a number of feature flags,
 bumps minimum required version to Erlang 25 for ARM64 CPU feature parity.
 
 The areas that have seen the biggest improvements in this release are

release-notes/3.12.0.md

@@ -0,0 +1,207 @@
+## RabbitMQ 3.12.0
+
+RabbitMQ 3.12 is a new feature release.
+
+## Highlights
+
+This release includes several new features and optimizations and graduates (makes mandatory) a number of feature flags.
+
+The user-facing areas that have seen the biggest improvements in this release are
+
+ * Lower MQTT and Web MQTT memory footprint per connection
+ * Classic queue message store memory efficiency and footprint predictability
+ * OAuth 2, OIDC, IDP support
+
+This release also features many internal API improvements in preparation to 4.0
+with [Khepri](https://www.youtube.com/watch?v=huT-zmXvfuM).
+
+See Compatibility Notes below to learn about breaking or potentially breaking changes in this release.
+
+## Obtaining Packages
+
+RabbitMQ releases are distributed via [GitHub](https://github.com/rabbitmq/rabbitmq-server/releases), [Cloudsmith](https://cloudsmith.io/~rabbitmq/repos/),
+and [PackageCloud](https://packagecloud.io/rabbitmq).
+
+
+### Erlang/OTP Compatibility Notes
+
+This release [requires Erlang 25.0](https://www.rabbitmq.com/which-erlang.html) or later.
+This introduces feature parity for x86- and ARM64-based CPUs: Erlang 25 offers the JIT and
+[modern Flame Graph profiling](https://blog.rabbitmq.com/posts/2022/05/flame-graphs/) tooling
+for both of those major CPU architectures.
+
+[Provisioning Latest Erlang Releases](https://www.rabbitmq.com/which-erlang.html#erlang-repositories) explains
+what package repositories and tools can be used to provision latest patch versions of Erlang 25.x.
+
+
+## Upgrading to 3.12
+
+### Documentation guides on upgrades
+
+See the [Upgrading guide](https://www.rabbitmq.com/upgrade.html) for documentation on upgrades and [RabbitMQ change log](https://www.rabbitmq.com/changelog.html)
+for release notes of other releases.
+
+### Required Feature Flags
+
+RabbitMQ 3.12.0 will require all feature flags from the 3.11.x release series to be enabled before upgrading,
+similarly to how [3.11.0 required all feature flags introduced before 3.9.0](https://blog.rabbitmq.com/posts/2022/07/required-feature-flags-in-rabbitmq-3.11/).
+
+If the feature flags are not enabled, RabbitMQ 3.12 and later nodes will refuse to start.
+
+### Mixed version cluster compatibility
+
+RabbitMQ 3.12.0 nodes can run alongside `3.11.x` nodes. `3.12.x`-specific features can only be made available when all nodes in the cluster
+upgrade to 3.12.0 or any other patch release in the new 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 3.12.0, 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).
+
+
+
+## Compatibility Notes
+
+### More Feature Flags Gratuate to Core Features ("Always Enabled")
+
+RabbitMQ 3.12.0 will require **all** feature flags from the 3.11.x release series to be enabled before upgrading.
+
+If the feature flags are not enabled, RabbitMQ 3.12 and later nodes will refuse to start.
+
+### Minimum Supported Erlang Version
+
+Starting with this release, RabbitMQ requires Erlang 25.0 or later versions. Nodes **will fail to start**
+on older Erlang releases.
+
+Erlang 25 as our new baseline means much improved performance on ARM64 architectures, [profiling with flame graphs](https://blog.rabbitmq.com/posts/2022/05/flame-graphs/)
+across all architectures, and the most recent TLS 1.3 implementation available to all RabbitMQ 3.11 users.
+
+
+### Client Library Compatibility
+
+Client libraries that were compatible with RabbitMQ `3.11.x` will be compatible with `3.12.0`.
+
+
+
+### Getting Help
+
+Any questions about this release, upgrades or RabbitMQ in general are welcome on the [RabbitMQ mailing list](https://groups.google.com/forum/#!forum/rabbitmq-users).
+
+
+
+## Changes Worth Mentioning
+
+Release notes are kept under [rabbitmq-server/release-notes](https://github.com/rabbitmq/rabbitmq-server/tree/v3.11.x/release-notes).
+
+### Core Server
+
+#### Bug Fixes
+
+All bug fixes worth mentioning in this release have also shipped
+in the `3.11.x` release series.
+
+#### Enhancements
+
+ * Reduced memory footprint, improved memory use predictability and throughput of classic queues.
+   This particularly benefits classic queues with longer backlogs.
+
+   GitHub issue: [#4522](https://github.com/rabbitmq/rabbitmq-server/pull/4522)
+
+ * Reduced peak memory footprint of quorum queues.
+
+   GitHub issue: [#7175](https://github.com/rabbitmq/rabbitmq-server/pull/7175)
+
+ * Improved stream leader distribution efficiency. Mostly relevant to environments with lots of
+   streams.
+
+   GitHub issue: [#6440](https://github.com/rabbitmq/rabbitmq-server/pull/6440)
+
+ * All [feature flags](https://www.rabbitmq.com/feature-flags.html) introduced before 3.11.0 are now required to be enabled. Make sure
+   all feature flags are enabled before upgrading to 3.12.0.
+
+   GitHub issue: [#7219](https://github.com/rabbitmq/rabbitmq-server/pull/7219)
+
+ * Plugin and core API: all schema data store operations are now available via the `rabbit_db_*` modules.
+   Plugin maintainers should switch to them for an easier transition to a future 4.0 release.
+
+   GitHub issues: [#6430](https://github.com/rabbitmq/rabbitmq-server/pull/6430), [#6821](https://github.com/rabbitmq/rabbitmq-server/pull/6821)
+
+ * Plugin and core API: node data directory now should be accessed using `rabbit:data_dir/0`.
+
+   GitHub issue: [#6462](https://github.com/rabbitmq/rabbitmq-server/pull/6462)
+
+ * Initial Erlang 26 compatibility
+
+   GitHub issues: [#7443](https://github.com/rabbitmq/rabbitmq-server/pull/7443), []()
+
+ * There is now a way to pre-configure user permissions for newly created virtual hosts.
+
+   Contributed by @illotum (AWS).
+
+   GitHub issue: [#7208](https://github.com/rabbitmq/rabbitmq-server/issues/7208).
+
+
+### CLI Tools
+
+#### Features
+
+ * `rabbitmq-streams restart_stream` is a new command that can be used to kick off
+   a new leader election for a stream. This can be used to rebalance stream leaders
+   across cluster nodes.
+
+   GitHub issue: [#6440](https://github.com/rabbitmq/rabbitmq-server/pull/6440)
+
+ * Classic queue metrics are now available via `rabbitmq-diagnostics observer`.
+
+   GitHub issue: [#3314](https://github.com/rabbitmq/rabbitmq-server/pull/3314)
+
+ * `rabbitmqctl set_permissions_globally` is a new command that sets up user permissions in all existing virtual hosts.
+
+   GitHub issue: [#1000](https://github.com/rabbitmq/rabbitmq-server/issues/1000)
+
+ * `rabbitmq-diagnostics cluster_status` now lists how many CPU cores are available to individual nodes, plus a total.
+
+   GitHub issue: [#7135](https://github.com/rabbitmq/rabbitmq-server/pull/7135)
+
+
+### MQTT Plugin
+
+#### Enhancements
+
+ * Significant (up to more than 90% with some workloads) reduction in memory footprint of MQTT connections,
+   and a double digit % reduction in memory footprint of MQTT-over-WebSockets (Web MQTT) connections.
+
+   GitHub issues: [#5895](https://github.com/rabbitmq/rabbitmq-server/pull/5895), [#7091](https://github.com/rabbitmq/rabbitmq-server/pull/7091), [#7234](https://github.com/rabbitmq/rabbitmq-server/pull/7234)
+
+
+### Management Plugin
+
+#### Enhancements
+
+ * Support for Identity Provider-initiated Login (IDP).
+
+   GitHub issues: [#6015](https://github.com/rabbitmq/rabbitmq-server/pull/6015), [#6201](https://github.com/rabbitmq/rabbitmq-server/pull/6201),
+   [#6247](https://github.com/rabbitmq/rabbitmq-server/pull/6247)
+
+
+### Consul Peer Discovery Plugin
+
+#### Bug Fixes
+
+ * Consul peer discovery now correctly determines if the node uses long or short names.
+
+   Contributed by @SimonUnge (AWS).
+
+   GitHub issue: [#4230](https://github.com/rabbitmq/rabbitmq-server/issues/4230)
+
+
+### Dependency Changes
+
+ * `ra` was upgraded [to `2.4.9`](https://github.com/rabbitmq/ra/releases)
+
+
+## Source Code Archives
+
+To obtain source code of the entire distribution, please download the archive named `rabbitmq-server-3.12.0.tar.xz`
+instead of the source tarball produced by GitHub.