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Improve & update release process to reflect recent changes (#3242)
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- Formalise release cadence guidelines
- Overhaul release steps to be easier to follow and more thorough
- Reorder changelog template to something more sensible
- Update release automation docs to reflect recent improvements (notably
  the addition of in-repo mypyc wheel builds)

Co-authored-by: Felix Hildén <felix.hilden@gmail.com>
Co-authored-by: Jelle Zijlstra <jelle.zijlstra@gmail.com>
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237 changes: 152 additions & 85 deletions docs/contributing/release_process.md
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# Release process

_Black_ has had a lot of work automating its release process. This document sets out to
explain what everything does and how to release _Black_ using said automation.

## Cutting a Release

To cut a release, you must be a _Black_ maintainer with `GitHub Release` creation
access. Using this access, the release process is:

1. Cut a new PR editing `CHANGES.md` and the docs to version the latest changes
_Black_ has had a lot of work done into standardizing and automating its release
process. This document sets out to explain how everything works and how to release
_Black_ using said automation.

## Release cadence

**We aim to release whatever is on `main` every 1-2 months.** This ensures merged
improvements and bugfixes are shipped to users reasonably quickly, while not massively
fracturing the user-base with too many versions. This also keeps the workload on
maintainers consistent and predictable.

If there's not much new on `main` to justify a release, it's acceptable to skip a
month's release. Ideally January releases should not be skipped because as per our
[stability policy](labels/stability-policy), the first release in a new calendar year
may make changes to the _stable_ style. While the policy applies to the first release
(instead of only January releases), confining changes to the stable style to January
will keep things predictable (and nicer) for users.

Unless there is a serious regression or bug that requires immediate patching, **there
should not be more than one release per month**. While version numbers are cheap,
releases require a maintainer to both commit to do the actual cutting of a release, but
also to be able to deal with the potential fallout post-release. Releasing more
frequently than monthly nets rapidly diminishing returns.

## Cutting a release

**You must have `write` permissions for the _Black_ repository to cut a release.**

The 10,000 foot view of the release process is that you prepare a release PR and then
publish a [GitHub Release]. This triggers [release automation](#release-workflows) that
builds all release artifacts and publishes them to the various platforms we publish to.

To cut a release:

1. Determine the release's version number
- **_Black_ follows the [CalVer] versioning standard using the `YY.M.N` format**
- So unless there already has been a release during this month, `N` should be `0`
- Example: the first release in January, 2022 → `22.1.0`
1. File a PR editing `CHANGES.md` and the docs to version the latest changes
1. Replace the `## Unreleased` header with the version number
1. Remove any empty sections for the current release
2. Add a new empty template for the next release (template below)
3. Example PR: [#2616](https://github.com/psf/black/pull/2616)
4. Example title: `Update CHANGES.md for XX.X release`
2. Once the release PR is merged ensure all CI passes
1. If not, ensure there is an Issue open for the cause of failing CI (generally we'd
want this fixed before cutting a release)
3. Open `CHANGES.md` and copy the _raw markdown_ of the latest changes to use in the
description of the GitHub Release.
4. Go and [cut a release](https://github.com/psf/black/releases) using the GitHub UI so
that all workflows noted below are triggered.
1. The release version and tag should be the [CalVer](https://calver.org) version
_Black_ used for the current release e.g. `21.6` / `21.5b1`
2. _Black_ uses [setuptools scm](https://pypi.org/project/setuptools-scm/) to pull
the current version for the package builds and release.
5. Once the release is cut, you're basically done. It's a good practice to go and watch
to make sure all the [GitHub Actions](https://github.com/psf/black/actions) pass,
although you should receive an email to your registered GitHub email address should
one fail.
1. You should see all the release workflows and lint/unittests workflows running on
the new tag in the Actions UI

If anything fails, please go read the respective action's log output and configuration
file to reverse engineer your way to a fix/soluton.

## Changelog template
1. (_optional_) Read through and copy-edit the changelog (eg. by moving entries,
fixing typos, or rephrasing entries)
1. Add a new empty template for the next release above
([template below](#changelog-template))
1. Update references to the latest version in
{doc}`/integrations/source_version_control` and
{doc}`/usage_and_configuration/the_basics`
- Example PR: [GH-3139]
1. Once the release PR is merged, wait until all CI passes
- If CI does not pass, **stop** and investigate the failure(s) as generally we'd want
to fix failing CI before cutting a release
1. [Draft a new GitHub Release][new-release]
1. Click `Choose a tag` and type in the version number, then select the
`Create new tag: YY.M.N on publish` option that appears
1. Verify that the new tag targets the `main` branch
1. You can leave the release title blank, GitHub will default to the tag name
1. Copy and paste the _raw changelog Markdown_ for the current release into the
description box
1. Publish the GitHub Release, triggering [release automation](#release-workflows) that
will handle the rest
1. At this point, you're basically done. It's good practice to go and [watch and verify
that all the release workflows pass][black-actions], although you will receive a
GitHub notification should something fail.
- If something fails, don't panic. Please go read the respective workflow's logs and
configuration file to reverse-engineer your way to a fix/solution.

Congratulations! You've successfully cut a new release of _Black_. Go and stand up and
take a break, you deserve it.

```{important}
Once the release artifacts reach PyPI, you may see new issues being filed indicating
regressions. While regressions are not great, they don't automatically mean a hotfix
release is warranted. Unless the regressions are serious and impact many users, a hotfix
release is probably unnecessary.
In the end, use your best judgement and ask other maintainers for their thoughts.
```

### Changelog template

Use the following template for a clean changelog after the release:

Expand All @@ -45,101 +90,123 @@ Use the following template for a clean changelog after the release:
<!-- Include any especially major or disruptive changes here -->
### Style
### Stable style
<!-- Changes that affect Black's stable style -->
### Preview style
<!-- Changes that affect Black's preview style -->
### _Blackd_
<!-- Changes to blackd -->
### Configuration
<!-- Changes to how Black can be configured -->
### Documentation
### Packaging
<!-- Major changes to documentation and policies. Small docs changes
don't need a changelog entry. -->
<!-- Changes to how Black is packaged, such as dependency requirements -->
### Integrations
### Parser
<!-- For example, Docker, GitHub Actions, pre-commit, editors -->
<!-- Changes to the parser or to version autodetection -->
### Performance
<!-- Changes that improve Black's performance. -->
### Output
<!-- Changes to Black's terminal output and error messages -->
### Packaging
<!-- Changes to how Black is packaged, such as dependency requirements -->
### _Blackd_
### Parser
<!-- Changes to blackd -->
<!-- Changes to the parser or to version autodetection -->
### Integrations
### Performance
<!-- For example, Docker, GitHub Actions, pre-commit, editors -->
<!-- Changes that improve Black's performance. -->
### Documentation
<!-- Major changes to documentation and policies. Small docs changes
don't need a changelog entry. -->
```

## Release workflows

All _Blacks_'s automation workflows use GitHub Actions. All workflows are therefore
configured using `.yml` files in the `.github/workflows` directory of the _Black_
All of _Black_'s release automation uses [GitHub Actions]. All workflows are therefore
configured using YAML files in the `.github/workflows` directory of the _Black_
repository.

They are triggered by the publication of a [GitHub Release].

Below are descriptions of our release workflows.

### Docker
### Publish to PyPI

This is our main workflow. It builds an [sdist] and [wheels] to upload to PyPI where the
vast majority of users will download Black from. It's divided into three job groups:

#### sdist + pure wheel

This workflow uses the QEMU powered `buildx` feature of docker to upload a `arm64` and
`amd64`/`x86_64` build of the official _Black_ docker image™.
This single job builds the sdist and pure Python wheel (i.e., a wheel that only contains
Python code) using [build] and then uploads them to PyPI using [twine]. These artifacts
are general-purpose and can be used on basically any platform supported by Python.

- Currently this workflow uses an API Token associated with @cooperlees account
#### mypyc wheels (…)

### pypi_upload
We use [mypyc] to compile _Black_ into a CPython C extension for significantly improved
performance. Wheels built with mypyc are platform and Python version specific.
[Supported platforms are documented in the FAQ](labels/mypyc-support).

This workflow builds a Python
[sdist](https://docs.python.org/3/distutils/sourcedist.html) and
[wheel](https://pythonwheels.com) using the latest
[setuptools](https://pypi.org/project/setuptools/) and
[wheel](https://pypi.org/project/wheel/) modules.
These matrix jobs use [cibuildwheel] which handles the complicated task of building C
extensions for many environments for us. Since building these wheels is slow, there are
multiple mypyc wheels jobs (hence the term "matrix") that build for a specific platform
(as noted in the job name in parentheses).

It will then use [twine](https://pypi.org/project/twine/) to upload both release formats
to PyPI for general downloading of the _Black_ Python package. This is where
[pip](https://pypi.org/project/pip/) looks by default.
Like the previous job group, the built wheels are uploaded to PyPI using [twine].

- Currently this workflow uses an API token associated with @ambv's PyPI account
#### Update stable branch

### Upload self-contained binaries
So this job doesn't _really_ belong here, but updating the `stable` branch after the
other PyPI jobs pass (they must pass for this job to start) makes the most sense. This
saves us from remembering to update the branch sometime after cutting the release.

This workflow builds self-contained binaries for multiple platforms. This allows people
to download the executable for their platform and run _Black_ without a
[Python Runtime](https://wiki.python.org/moin/PythonImplementations) installed.
- _Currently this workflow uses an API token associated with @ambv's PyPI account_

The created binaries are attached/stored on the associated
[GitHub Release](https://github.com/psf/black/releases) for download over _IPv4 only_
(GitHub still does not have IPv6 access 😢).
### Publish executables

## Moving the `stable` tag
This workflow builds native executables for multiple platforms using [PyInstaller]. This
allows people to download the executable for their platform and run _Black_ without a
[Python runtime](https://wiki.python.org/moin/PythonImplementations) installed.

_Black_ provides a stable tag for people who want to move along as _Black_ developers
deem the newest version reliable. Here the _Black_ developers will move once the release
has been problem free for at least ~24 hours from release. Given the large _Black_
userbase we hear about bad bugs quickly. We do strive to continually improve our CI too.
The created binaries are stored on the associated GitHub Release for download over _IPv4
only_ (GitHub still does not have IPv6 access 😢).

### Tag moving process
### docker

#### stable
This workflow uses the QEMU powered `buildx` feature of Docker to upload an `arm64` and
`amd64`/`x86_64` build of the official _Black_ Docker image™.

From a rebased `main` checkout:
- _Currently this workflow uses an API Token associated with @cooperlees account_

```{note}
This also runs on each push to `main`.
```

1. `git tag -f stable VERSION_TAG`
1. e.g. `git tag -f stable 21.5b1`
1. `git push --tags -f`
[black-actions]: https://github.com/psf/black/actions
[build]: https://pypa-build.readthedocs.io/
[calver]: https://calver.org
[cibuildwheel]: https://cibuildwheel.readthedocs.io/
[gh-3139]: https://github.com/psf/black/pull/3139
[github actions]: https://github.com/features/actions
[github release]: https://github.com/psf/black/releases
[new-release]: https://github.com/psf/black/releases/new
[mypyc]: https://mypyc.readthedocs.io/
[mypyc-platform-support]:
/faq.html#what-is-compiled-yes-no-all-about-in-the-version-output
[pyinstaller]: https://www.pyinstaller.org/
[sdist]:
https://packaging.python.org/en/latest/glossary/#term-Source-Distribution-or-sdist
[twine]: https://github.com/features/actions
[wheels]: https://packaging.python.org/en/latest/glossary/#term-Wheel
2 changes: 2 additions & 0 deletions docs/faq.md
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Expand Up @@ -114,6 +114,8 @@ errors is not a goal. It can format all code accepted by CPython (if you find an
where that doesn't hold, please report a bug!), but it may also format some code that
CPython doesn't accept.

(labels/mypyc-support)=

## What is `compiled: yes/no` all about in the version output?

While _Black_ is indeed a pure Python project, we use [mypyc] to compile _Black_ into a
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2 changes: 2 additions & 0 deletions docs/the_black_code_style/index.md
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Expand Up @@ -19,6 +19,8 @@ style aspects and details might change according to the stability policy present
below. Ongoing style considerations are tracked on GitHub with the
[design](https://github.com/psf/black/labels/T%3A%20design) issue label.

(labels/stability-policy)=

## Stability Policy

The following policy applies for the _Black_ code style, in non pre-release versions of
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