Release process

How to release a new version of pantsbuild.pants and its plugins.

This page covers the nitty-gritty of executing a release, and is probably only interesting for maintainers. If you're interested in when and why Pants is released, please see the Release strategy page.


1. Create a PGP signing key

If you already have one, you can reuse it.

You likely want to use the gpg implementation of pgp. On macOS, you can brew install gpg. Once gpg is installed, generate a new key: https://docs.github.com/en/github/authenticating-to-github/generating-a-new-gpg-key.

Please use a password for your key!

2. Add your PGP key to GitHub.

See https://docs.github.com/en/github/authenticating-to-github/adding-a-new-gpg-key-to-your-github-account.

3. Configure Git to use your PGP key.

See https://docs.github.com/en/github/authenticating-to-github/telling-git-about-your-signing-key.

Note: the last step is required on macOS.

4. Authenticate with the Github API

Ensure that you have a personal access token for your Github account in your .netrc file.

machine api.github.com
    login <username>
    password <token>

Step 1: Prepare the release

The release is automated, outside of these steps:

  1. Removing any completed deprecations
  2. Changelog preparation
  3. CONTRIBUTOR.md updates
  4. Version bumping

The first three steps always happen in the main branch, whereas the version bump happens in the relevant release branch.

For dev and a0 releases, the release branch is main. For all other release candidates and stable releases, the release branch is that respective version's branch, e.g. 2.8.x or 2.9.x.

0a. dev0 - set up the release series

  1. Create a new file in src/python/pants/notes, e.g. create src/python/pants/notes/2.9.x.md.
    1. Copy the title and template over from the prior release, e.g. 2.8.x.md.
  2. Add the new file to pants.toml in the release_notes section.

0b. dev - Check for any deprecations

Your release will fail if there are any deprecated things that should now be removed. Usually, the person who deprecated the feature should have already removed the stale code, but they may have forgotten.

To check for this, search for the version you are releasing. For example, with ripgrep, run rg -C3 2.9.0.dev0.

If there are things that must be removed, you can either:

  1. Ping the person who made the deprecation to ask them to remove it.
  2. Remove it yourself, either in the release prep or as a precursor PR.
  3. Bump the removal date back by one dev release.

0c. Release candidates - cherry-pick relevant changes

Cherry-pick all changes labeled needs-cherrypick with the relevant milestone for the stable branch, e.g. the milestone 2.9.x.

These pull requests must have been merged into main first, so they will already be closed.

To cherry-pick, for example, from 2.9.x:

  1. git fetch https://github.com/pantsbuild/pants 2.9.x
  2. git checkout -b <new-branch-name> FETCH_HEAD
  3. Find the commit SHA by running git log main or looking in GitHub: https://github.com/pantsbuild/pants/commits/main.
  4. git cherry-pick <sha>, using the SHA from the previous step.
  5. Open a pull request to merge into the release branch, e.g. 2.9.x.

Do not push directly to the release branch. All changes should be added through a pull request.

After a commit has been cherry-picked, remove the needs-cherrypick label and remove it from the release milestone.

1. Prepare the changelog

Update the release page in src/python/pants/notes for this release series, e.g. update src/python/pants/notes/2.9.x.md.

Run git fetch --all --tags to be sure you have the latest release tags available locally.

From the main branch, run pants run build-support/bin/changelog.py -- --prior 2.9.0.dev0 --new 2.9.0.dev1 with the relevant versions.

This will generate the sections to copy into the release notes. Delete any empty sections. Do not paste the Internal section into the notes file. Instead, paste into a comment on the prep PR.

You are encouraged to fix typos and tweak change descriptions for clarity to users. Ensure that there is exactly one blank line between descriptions, headers etc.


Reminder: always do this against the main branch

Even if you are preparing notes for a release candidate, always prepare the notes in a branch based on main and, later, target your PR to merge with main.


See any weird PR titles?

Sometimes, committers accidentally use the wrong title when squashing and merging because GitHub pulls the title from the commit title when there is only one commit.

If you see a vague or strange title like "fix bug", open the original PR to see if the PR title is more descriptive. If it is, please use the more descriptive title instead.


Run pants run build-support/bin/contributors.py

Take note of any new contributors since the last release so that you can give a shoutout in the announcement email.

If this is a stable release, then you can use git diff to find all new contributors since the previous stable release, to give them all a shoutout in the stable release email. E.g.,

git diff release_2.8.0..release_2.9.0 CONTRIBUTORS.md

3. dev and a0 - bump the VERSION

Change src/python/pants/VERSION to the new release, e.g. 2.12.0.dev0. If you encounter an a0 version on main, then the next release will be for a new release series (i.e. you'll bump from 2.12.0a0 to 2.13.0.dev0).

4. Post the prep to GitHub

Open a pull request on GitHub to merge into main. Post the PR to the #development in Slack.

Merge once approved and green.


Watch out for any recently landed PRs

From the time you put up your release prep until you hit "merge", be careful that no one merges any commits into main.

If they doโ€”and you're doing a dev or a0 releaseโ€”you should merge main into your PR and update the changelog with their changes. It's okay if the changes were internal only, but any public changes must be added to the changelog.

Once you click "merge", it is safe for people to merge changes again.

5a. a0 - create a new Git branch

For example, if you're releasing 2.9.0a0, create the branch 2.9.x by running the below. Make sure you are on your release commit before doing this.

$ git checkout -b 2.9.x
$ git push upstream 2.9.x

5b. release candidates - cherry-pick and bump the VERSION

  1. Checkout from main into the release branch, e.g. 2.9.x.
  2. Cherry-pick the release prep using git cherry-pick <sha>.
  3. Bump the VERSION in src/python/pants/VERSION, e.g. to 2.9.0rc1. Push this as a new commit directly to the release branch - you do not need to open a pull request.

Step 2: Update this docs site

Note that this step can currently only be performed by a subset of maintainers due to a paid maximum number of seats. If you do not have a readme.com account, contact someone in the #maintainers-confidential channel in Slack to help out.

dev0 - set up the new version

Go to the documentation dashboard. In the top left dropdown, where it says the current version, click "Manage versions". Click "Add new version" and use a "v" with the minor release number, e.g. "v2.9". Fork from the prior release. Mark this new version as public by clicking on "Is public?"

Sync the docs/ content

See the docs/NOTES.md for instructions setting up the the necessary Node tooling your first time.
You'll need to 1st login as outlined there via some variant of npx rdme login --2fa --project pants ....
On the relevant release branch, run npx rdme docs docs/markdown --version v<pants major>.<pants minor>; e.g: npx rdme docs docs/markdown --version v2.8.

Regenerate the references

Still on the relevant release branch, run pants run build-support/bin/generate_docs.py -- --sync --api-key <key> with your key from https://dash.readme.com/project/pants/v2.8/api-key.

stable releases - Update the default docsite

The first stable release of a branch should update the "default" version of the docsite. For example: when releasing the stable 2.9.0, the docsite would be changed to pointing from v2.8 to pointing to v2.9 by default.

Also, update the Changelog's "highlights" column with a link to the blog summarizing the release. See the section "Announce the release" below for more info on the blog.


Don't have edit access?

Ping someone in the #maintainers-confidential channel in Slack to be added. Alternatively, you can "Suggest edits" in the top right corner.

Step 3: Tag the release to build wheels

Once you have merged the VERSION bump โ€” which will be on main for dev and a0 releases and the release branch for release candidates โ€” you should tag the release commit to trigger wheel building and PyPI publishing.

First, ensure that you are on your release branch at your version bump commit.


Tip: if new commits have landed after your release commit

You can reset to your release commit by running git reset --hard <sha>.

Then, run:

./build-support/bin/release.sh tag-release

This will tag the release with your PGP key, and push the tag to origin, which will kick off a Release job to build the wheels and publish them to PyPI.

Step 4: Release a Pants PEX

After the Release job for your tag has completed, you should additionally build and publish the "universal" PEX to Github.

PANTS_PEX_RELEASE=STABLE ./build-support/bin/release.sh build-universal-pex

Then go to https://github.com/pantsbuild/pants/tags, find your release's tag, click Edit tag, and upload the PEX located at dist/pex.pants.<version>.pex.

Step 5: Test the release

Run this script as a basic smoke test:

./build-support/bin/release.sh test-release

You should also check PyPI to ensure everything looks good. Click "Release history" to find the version you released, then click it and confirm the changelog is correct on the "Project description" page and that the macOS and manylinux wheels show up in the "Download files" page.

Step 6: Announce the change

Announce the release to:

  1. the pants-devel list
  2. the #announce channel in Slack

Sample emails for pants-devel

You can get a contributor list by running the following, where <tag> is the tag for the prior release (eg: release_2.9.0.dev0):

pants run ./build-support/bin/contributors.py -- -s <tag>


Update the links in these templates!

When copy pasting these templates, please always check that all versions match the relevant release. When adding a link, use "Test this link" to ensure that it loads properly.

Dev release

If the release series' .dev0 has already been released, reply to that email thread for the rest of the dev releases.

Subject: [dev release] pantsbuild.pants 2.9.0.dev0

The first weekly dev release for the 2.9 series is now available on PyPI! Please visit the release page to see the changelog.

Thank you to this week's contributors:

Eustolia Palledino
Ahmad Wensel
Rae Efird
Niki Fitch

And a special shout-out to first-time contributor Niki Fitch, with the PR Upgrade Rust to 1.63 (#9441). Thank you for your contribution!

(For more information on how Pants is released, please see the release strategy page.)

Alpha release

Reply to the email thread for the series' dev releases.

Subject: [alpha release] pantsbuild.pants 2.9.0a0

The first alpha release for 2.9.0 is now available on PyPI! Please visit the release page to see the changelog.

Although alpha releases have not received any vetting beyond what a dev release receives, they are the first release for their stable branch, and are worth trying out to help report bugs before we start release candidates.

Thank you to everyone who contributed patches in this cycle!

Niki Fitch
Mario Rozell

(For more information on how Pants is released, please see the release strategy page.)

Release candidate

Create a new email thread for rc0. For other rcs, reply to the email thread for the rest of the patch's release candidates. That is, bundle 2.9.0 release candidates together, and 2.8.1 candidates together, etc.

Subject: [release candidate] pantsbuild.pants 2.9.0rc1

The second release candidate for 2.9.0 is now available on PyPI! Please visit the release page to see the changelog.

Thank you to everyone who tested the previous release, and thank you to the folks who contributed patches!

Niki Fitch
Mario Rozell

(For more information on how Pants is released, please see the release strategy page.)

Stable release

For the first stable release in the series, first, write a blog post to summarize the series using https://pants.ghost.io/ghost/#/site. Please coordinate by posting to #development in Slack. If writing is not your thing, you can ask in #maintainers or #development if another Pants contributor would be willing to write the blog.

Subject: [stable release] pantsbuild.pants 2.9.0

The first stable release of the 2.9 series is now available on PyPI!

See our blog post summarizing the release series, or the more detailed changelog on the release page.

Thanks to all of the contributors to the 2.9 series!

Eustolia Palledino
Ahmad Wensel
Rae Efird
Niki Fitch
Mario Rozell

(For more information on how Pants is released, please see the release strategy page.)

When Things Go Wrong

From time to time, a release will fail. It's a complex process. The first thing to do after you've
exhausted your knowledge and debugging skills or patience is to contact others. You might reach out
to the development or maintainers channels on Pantbuild Slack in the absence of other ideas about
whom to ask for help.

Some issues are well known or well understood, and they are documented here.

https://binaries.pantsbuild.com outage / missing wheels

The https://binaries.pantsbuild.com site is an S3 bucket that houses Pantsbuild wheels generated in
CI and used as part of the release process. If there are missing wheels or the wheels can't be
fetched due to connectivity issues or an S3 outage, you'll learn about this through the release
script erroring out. The script is idempotent; so you can just run it again, potentially waiting
longer for wheels to be built in CI or outages to clear.

When the release script finishes, it creates and pushes a release tag. This will trigger a release
GitHub workflow
could ~silently error later if there were to be an S3 outage. This job currently is responsible for
pushing a file mapping the release tag to the commit it tags out to
https://binaries.pantsbuild.com/tags/pantsbuild.pants/<tag>. If the tag is missing, it should be
fixed by running the following in an environment where you have both AWS_ACCESS_KEY_ID and
AWS_SECRET_ACCESS_KEY of an account that has permissions to push to the Pantsbuild S3 bucket:

pants run build-support/bin/backfill_s3_release_tag_mappings.py -- \
   --aws-cli-symlink-path $HOME/bin

If this sounds mysterious or new to you, you probably don't have such an account and should ask for
help from other maintainers. You may want to adjust the --aws-cli-symlink-path to your liking as
well, consult --help for more information.