poky/documentation/ref-manual/release-process.rst - mdmillerii/openbmc - Gitiles

 .. SPDX-License-Identifier: CC-BY-SA-2.0-UK

 *****************************************************
 Yocto Project Releases and the Stable Release Process
 *****************************************************

 The Yocto Project release process is predictable and consists of both
 major and minor (point) releases. This brief chapter provides
 information on how releases are named, their life cycle, and their
 stability.

 Major and Minor Release Cadence
 ===============================

 The Yocto Project delivers major releases (e.g. &DISTRO;) using a six
 month cadence roughly timed each April and October of the year.
 Following are examples of some major YP releases with their codenames
 also shown. See the ":ref:`ref-manual/release-process:major release codenames`"
 section for information on codenames used with major releases.

   - 4.1 ("Langdale")
   - 4.0 ("Kirkstone")
   - 3.4 ("Honister")

 While the cadence is never perfect, this timescale facilitates
 regular releases that have strong QA cycles while not overwhelming users
 with too many new releases. The cadence is predictable and avoids many
 major holidays in various geographies.

 The Yocto project delivers minor (point) releases on an unscheduled
 basis and are usually driven by the accumulation of enough significant
 fixes or enhancements to the associated major release. Following are
 some example past point releases:

   - 4.1.3
   - 4.0.8
   - 3.4.4

 The point release
 indicates a point in the major release branch where a full QA cycle and
 release process validates the content of the new branch.

 .. note::

    Realize that there can be patches merged onto the stable release
    branches as and when they become available.

 Major Release Codenames
 =======================

 Each major release receives a codename that identifies the release in
 the :ref:`overview-manual/development-environment:yocto project source repositories`.
 The concept is that branches of :term:`Metadata` with the same
 codename are likely to be compatible and thus work together.

 .. note::

    Codenames are associated with major releases because a Yocto Project
    release number (e.g. &DISTRO;) could conflict with a given layer or
    company versioning scheme. Codenames are unique, interesting, and
    easily identifiable.

 Releases are given a nominal release version as well but the codename is
 used in repositories for this reason. You can find information on Yocto
 Project releases and codenames at :yocto_wiki:`/Releases`.

 Our :doc:`/migration-guides/index` detail how to migrate from one release of
 the Yocto Project to the next.

 Stable Release Process
 ======================

 Once released, the release enters the stable release process at which
 time a person is assigned as the maintainer for that stable release.
 This maintainer monitors activity for the release by investigating and
 handling nominated patches and backport activity. Only fixes and
 enhancements that have first been applied on the "master" branch (i.e.
 the current, in-development branch) are considered for backporting to a
 stable release.

 .. note::

    The current Yocto Project policy regarding backporting is to consider
    bug fixes and security fixes only. Policy dictates that features are
    not backported to a stable release. This policy means generic recipe
    version upgrades are unlikely to be accepted for backporting. The
    exception to this policy occurs when there is a strong reason such as
    the fix happens to also be the preferred upstream approach.

 .. _ref-long-term-support-releases:

 Long Term Support Releases
 ==========================

 While stable releases are supported for a duration of seven months,
 some specific ones are now supported for a longer period by the Yocto
 Project, and are called Long Term Support (:term:`LTS`) releases.

 When significant issues are found, :term:`LTS` releases allow to publish
 fixes not only for the current stable release, but also to the
 :term:`LTS` releases that are still supported. Older stable releases which
 have reached their End of Life (EOL) won't receive such updates.

 This started with version 3.1 ("Dunfell"), released in April 2020, which
 the project initially committed to supporting for two years, but this duration
 was later extended to four years. Similarly, the following :term:`LTS` release,
 version 4.0 ("Kirkstone"), was released two years later in May 2022 and the
 project committed to supporting it for four years too.

 Therefore, a new :term:`LTS` release is made every two years and is supported
 for four years. This offers more stability to project users and leaves more
 time to upgrade to the following :term:`LTS` release.

 See :yocto_wiki:`/Stable_Release_and_LTS` for details about the management
 of stable and :term:`LTS` releases.

 .. image:: svg/releases.*
    :width: 100%

 .. note::

    In some circumstances, a layer can be created by the community in order to
    add a specific feature or support a new version of some package for an :term:`LTS`
    release. This is called a :term:`Mixin` layer. These are thin and specific
    purpose layers which can be stacked with an :term:`LTS` release to "mix" a specific
    feature into that build. These are created on an as-needed basis and
    maintained by the people who need them.

    Policies on testing these layers depend on how widespread their usage is and
    determined on a case-by-case basis. You can find some :term:`Mixin` layers in the
    :yocto_git:`meta-lts-mixins </meta-lts-mixins>` repository. While the Yocto
    Project provides hosting for those repositories, it does not provides
    testing on them. Other :term:`Mixin` layers may be released elsewhere by the wider
    community.

 Testing and Quality Assurance
 =============================

 Part of the Yocto Project development and release process is quality
 assurance through the execution of test strategies. Test strategies
 provide the Yocto Project team a way to ensure a release is validated.
 Additionally, because the test strategies are visible to you as a
 developer, you can validate your projects. This section overviews the
 available test infrastructure used in the Yocto Project. For information
 on how to run available tests on your projects, see the
 ":ref:`dev-manual/runtime-testing:performing automated runtime testing`"
 section in the Yocto Project Development Tasks Manual.

 The QA/testing infrastructure is woven into the project to the point
 where core developers take some of it for granted. The infrastructure
 consists of the following pieces:

 -  ``bitbake-selftest``: A standalone command that runs unit tests on
    key pieces of BitBake and its fetchers.

 -  :ref:`ref-classes-sanity`: This automatically
    included class checks the build environment for missing tools (e.g.
    ``gcc``) or common misconfigurations such as
    :term:`MACHINE` set incorrectly.

 -  :ref:`ref-classes-insane`: This class checks the
    generated output from builds for sanity. For example, if building for
    an ARM target, did the build produce ARM binaries. If, for example,
    the build produced PPC binaries then there is a problem.

 -  :ref:`ref-classes-testimage`: This class
    performs runtime testing of images after they are built. The tests
    are usually used with :doc:`QEMU </dev-manual/qemu>`
    to boot the images and check the combined runtime result boot
    operation and functions. However, the test can also use the IP
    address of a machine to test.

 -  :ref:`ptest <dev-manual/packages:testing packages with ptest>`:
    Runs tests against packages produced during the build for a given
    piece of software. The test allows the packages to be run within a
    target image.

 -  ``oe-selftest``: Tests combination BitBake invocations. These tests
    operate outside the OpenEmbedded build system itself. The
    ``oe-selftest`` can run all tests by default or can run selected
    tests or test suites.

 Originally, much of this testing was done manually. However, significant
 effort has been made to automate the tests so that more people can use
 them and the Yocto Project development team can run them faster and more
 efficiently.

 The Yocto Project's main Autobuilder (&YOCTO_AB_URL;) publicly tests each Yocto
 Project release's code in the :oe_git:`openembedded-core </openembedded-core>`,
 :yocto_git:`poky </poky>` and :oe_git:`bitbake </bitbake>` repositories. The
 testing occurs for both the current state of the "master" branch and also for
 submitted patches. Testing for submitted patches usually occurs in the
 in the "master-next" branch in the :yocto_git:`poky </poky>` repository.

 .. note::

    You can find all these branches in the
    :ref:`overview-manual/development-environment:yocto project source repositories`.

 Testing within these public branches ensures in a publicly visible way
 that all of the main supposed architectures and recipes in OE-Core
 successfully build and behave properly.

 Various features such as ``multilib``, sub architectures (e.g. ``x32``,
 ``poky-tiny``, ``musl``, ``no-x11`` and and so forth),
 ``bitbake-selftest``, and ``oe-selftest`` are tested as part of the QA
 process of a release. Complete testing and validation for a release
 takes the Autobuilder workers several hours.

 .. note::

    The Autobuilder workers are non-homogeneous, which means regular
    testing across a variety of Linux distributions occurs. The
    Autobuilder is limited to only testing QEMU-based setups and not real
    hardware.

 Finally, in addition to the Autobuilder's tests, the Yocto Project QA
 team also performs testing on a variety of platforms, which includes
 actual hardware, to ensure expected results.
	.. SPDX-License-Identifier: CC-BY-SA-2.0-UK

	*****************************************************
	Yocto Project Releases and the Stable Release Process
	*****************************************************

	The Yocto Project release process is predictable and consists of both
	major and minor (point) releases. This brief chapter provides
	information on how releases are named, their life cycle, and their
	stability.

	Major and Minor Release Cadence
	===============================

	The Yocto Project delivers major releases (e.g. &DISTRO;) using a six
	month cadence roughly timed each April and October of the year.
	Following are examples of some major YP releases with their codenames
	also shown. See the ":ref:`ref-manual/release-process:major release codenames`"
	section for information on codenames used with major releases.

	- 4.1 ("Langdale")
	- 4.0 ("Kirkstone")
	- 3.4 ("Honister")

	While the cadence is never perfect, this timescale facilitates
	regular releases that have strong QA cycles while not overwhelming users
	with too many new releases. The cadence is predictable and avoids many
	major holidays in various geographies.

	The Yocto project delivers minor (point) releases on an unscheduled
	basis and are usually driven by the accumulation of enough significant
	fixes or enhancements to the associated major release. Following are
	some example past point releases:

	- 4.1.3
	- 4.0.8
	- 3.4.4

	The point release
	indicates a point in the major release branch where a full QA cycle and
	release process validates the content of the new branch.

	.. note::

	Realize that there can be patches merged onto the stable release
	branches as and when they become available.

	Major Release Codenames
	=======================

	Each major release receives a codename that identifies the release in
	the :ref:`overview-manual/development-environment:yocto project source repositories`.
	The concept is that branches of :term:`Metadata` with the same
	codename are likely to be compatible and thus work together.

	.. note::

	Codenames are associated with major releases because a Yocto Project
	release number (e.g. &DISTRO;) could conflict with a given layer or
	company versioning scheme. Codenames are unique, interesting, and
	easily identifiable.

	Releases are given a nominal release version as well but the codename is
	used in repositories for this reason. You can find information on Yocto
	Project releases and codenames at :yocto_wiki:`/Releases`.

	Our :doc:`/migration-guides/index` detail how to migrate from one release of
	the Yocto Project to the next.

	Stable Release Process
	======================

	Once released, the release enters the stable release process at which
	time a person is assigned as the maintainer for that stable release.
	This maintainer monitors activity for the release by investigating and
	handling nominated patches and backport activity. Only fixes and
	enhancements that have first been applied on the "master" branch (i.e.
	the current, in-development branch) are considered for backporting to a
	stable release.

	.. note::

	The current Yocto Project policy regarding backporting is to consider
	bug fixes and security fixes only. Policy dictates that features are
	not backported to a stable release. This policy means generic recipe
	version upgrades are unlikely to be accepted for backporting. The
	exception to this policy occurs when there is a strong reason such as
	the fix happens to also be the preferred upstream approach.

	.. _ref-long-term-support-releases:

	Long Term Support Releases
	==========================

	While stable releases are supported for a duration of seven months,
	some specific ones are now supported for a longer period by the Yocto
	Project, and are called Long Term Support (:term:`LTS`) releases.

	When significant issues are found, :term:`LTS` releases allow to publish
	fixes not only for the current stable release, but also to the
	:term:`LTS` releases that are still supported. Older stable releases which
	have reached their End of Life (EOL) won't receive such updates.

	This started with version 3.1 ("Dunfell"), released in April 2020, which
	the project initially committed to supporting for two years, but this duration
	was later extended to four years. Similarly, the following :term:`LTS` release,
	version 4.0 ("Kirkstone"), was released two years later in May 2022 and the
	project committed to supporting it for four years too.

	Therefore, a new :term:`LTS` release is made every two years and is supported
	for four years. This offers more stability to project users and leaves more
	time to upgrade to the following :term:`LTS` release.

	See :yocto_wiki:`/Stable_Release_and_LTS` for details about the management
	of stable and :term:`LTS` releases.

	.. image:: svg/releases.*
	:width: 100%

	.. note::

	In some circumstances, a layer can be created by the community in order to
	add a specific feature or support a new version of some package for an :term:`LTS`
	release. This is called a :term:`Mixin` layer. These are thin and specific
	purpose layers which can be stacked with an :term:`LTS` release to "mix" a specific
	feature into that build. These are created on an as-needed basis and
	maintained by the people who need them.

	Policies on testing these layers depend on how widespread their usage is and
	determined on a case-by-case basis. You can find some :term:`Mixin` layers in the
	:yocto_git:`meta-lts-mixins </meta-lts-mixins>` repository. While the Yocto
	Project provides hosting for those repositories, it does not provides
	testing on them. Other :term:`Mixin` layers may be released elsewhere by the wider
	community.

	Testing and Quality Assurance
	=============================

	Part of the Yocto Project development and release process is quality
	assurance through the execution of test strategies. Test strategies
	provide the Yocto Project team a way to ensure a release is validated.
	Additionally, because the test strategies are visible to you as a
	developer, you can validate your projects. This section overviews the
	available test infrastructure used in the Yocto Project. For information
	on how to run available tests on your projects, see the
	":ref:`dev-manual/runtime-testing:performing automated runtime testing`"
	section in the Yocto Project Development Tasks Manual.

	The QA/testing infrastructure is woven into the project to the point
	where core developers take some of it for granted. The infrastructure
	consists of the following pieces:

	- ``bitbake-selftest``: A standalone command that runs unit tests on
	key pieces of BitBake and its fetchers.

	- :ref:`ref-classes-sanity`: This automatically
	included class checks the build environment for missing tools (e.g.
	``gcc``) or common misconfigurations such as
	:term:`MACHINE` set incorrectly.

	- :ref:`ref-classes-insane`: This class checks the
	generated output from builds for sanity. For example, if building for
	an ARM target, did the build produce ARM binaries. If, for example,
	the build produced PPC binaries then there is a problem.

	- :ref:`ref-classes-testimage`: This class
	performs runtime testing of images after they are built. The tests
	are usually used with :doc:`QEMU </dev-manual/qemu>`
	to boot the images and check the combined runtime result boot
	operation and functions. However, the test can also use the IP
	address of a machine to test.

	- :ref:`ptest <dev-manual/packages:testing packages with ptest>`:
	Runs tests against packages produced during the build for a given
	piece of software. The test allows the packages to be run within a
	target image.

	- ``oe-selftest``: Tests combination BitBake invocations. These tests
	operate outside the OpenEmbedded build system itself. The
	``oe-selftest`` can run all tests by default or can run selected
	tests or test suites.

	Originally, much of this testing was done manually. However, significant
	effort has been made to automate the tests so that more people can use
	them and the Yocto Project development team can run them faster and more
	efficiently.

	The Yocto Project's main Autobuilder (&YOCTO_AB_URL;) publicly tests each Yocto
	Project release's code in the :oe_git:`openembedded-core </openembedded-core>`,
	:yocto_git:`poky </poky>` and :oe_git:`bitbake </bitbake>` repositories. The
	testing occurs for both the current state of the "master" branch and also for
	submitted patches. Testing for submitted patches usually occurs in the
	in the "master-next" branch in the :yocto_git:`poky </poky>` repository.

	.. note::

	You can find all these branches in the
	:ref:`overview-manual/development-environment:yocto project source repositories`.

	Testing within these public branches ensures in a publicly visible way
	that all of the main supposed architectures and recipes in OE-Core
	successfully build and behave properly.

	Various features such as ``multilib``, sub architectures (e.g. ``x32``,
	``poky-tiny``, ``musl``, ``no-x11`` and and so forth),
	``bitbake-selftest``, and ``oe-selftest`` are tested as part of the QA
	process of a release. Complete testing and validation for a release
	takes the Autobuilder workers several hours.

	.. note::

	The Autobuilder workers are non-homogeneous, which means regular
	testing across a variety of Linux distributions occurs. The
	Autobuilder is limited to only testing QEMU-based setups and not real
	hardware.

	Finally, in addition to the Autobuilder's tests, the Yocto Project QA
	team also performs testing on a variety of platforms, which includes
	actual hardware, to ensure expected results.