release-notes

Kubernetes Release Notes

djmm@google.com
Last Updated: 2016-04-06

Objective

Define a process and design tooling for collecting, arranging and publishing release notes for Kubernetes releases, automating as much of the process as possible.

The goal is to introduce minor changes to the development workflow in a way that is mostly frictionless and allows for the capture of release notes as PRs are submitted to the repository.

This direct association of release notes to PRs captures the intention of release visibility of the PR at the point an idea is submitted upstream. The release notes can then be more easily collected and published when the release is ready.

Background

The Problem

Release notes are often an afterthought and clarifying and finalizing them is often left until the very last minute at the time the release is made. This is usually long after the feature or bug fix was added and is no longer on the mind of the author. Worse, the collecting and summarizing of the release is often left to those who may know little or nothing about these individual changes!

Writing and editing release notes at the end of the cycle can be a rushed, interrupt-driven and often stressful process resulting in incomplete, inconsistent release notes often with errors and omissions.

The (general) Solution

Like most things in the development/release pipeline, the earlier you do it, the easier it is for everyone and the better the outcome. Gather your release notes earlier in the development cycle, at the time the features and fixes are added.

Then why not just list every change that was submitted, CHANGELOG-style?

On larger projects like Kubernetes, showing every single change (PR) would mean hundreds of entries. The goal is to highlight the major changes for a release.

Options

  1. Use of pre-commit and other local git hooks
    • Experiments here using prepare-commit-msg and commit-msg git hook files were promising but less than optimal due to the fact that they would require input/confirmation with each commit and there may be multiple commits in a push and eventual PR.
  2. Use of github templates
    • Templates provide a great way to pre-fill PR comments, but there are no server-side hooks available to parse and/or easily check the contents of those templates to ensure that checkboxes were checked or forms were filled in.
  3. Use of labels enforced by mungers/bots
    • We already make great use of mungers/bots to manage labels on PRs and it fits very nicely in the existing workflow

Collection Design

The munger/bot option fits most cleanly into the existing workflow.

All release-note-* labeling is managed on the master branch PR only. No release-note-* labels are needed on cherry-pick PRs and no information will be collected from that cherry-pick PR.

The only exception to this rule is when a PR is not a cherry-pick and is targeted directly to the non-master branch. In this case, a release-note-* label is required for that non-master PR.

  1. New labels added to github: release-note-none, maybe others for new release note categories - see Layout section below
  2. A new munger that will:
    • Add a release-note-label-needed label to all new master branch PRs
    • Block merge by the submit queue on all PRs labeled as release-note-label-needed
    • Auto-remove release-note-label-needed when one of the release-note-* labels is added

Publishing Design

Location

With v1.2.0, the release notes were moved from their previous github releases location to CHANGELOG.md. Going forward this seems like a good plan. Other projects do similarly.

The kubernetes.tar.gz download link is also displayed along with the release notes in CHANGELOG.md.

Is there any reason to continue publishing anything to github releases if the complete release story is published in CHANGELOG.md?

Layout

Different types of releases will generally have different requirements in terms of layout. As expected, major releases like v1.2.0 are going to require much more detail than the automated release notes will provide.

The idea is that these mechanisms will provide 100% of the release note content for alpha, beta and most minor releases and bootstrap the content with a release note ‘template’ for the authors of major releases like v1.2.0.

The authors can then collaborate and edit the higher level sections of the release notes in a PR, updating CHANGELOG.md as needed.

v1.2.0 demonstrated the need, at least for major releases like v1.2.0, for several sections in the published release notes. In order to provide a basic layout for release notes in the future, new releases can bootstrap CHANGELOG.md with the following template types:

Alpha/Beta/Patch Releases

These are automatically generated from release-note* labels, but can be modified as needed.

Action Required
* PR titles from the release-note-action-required label

Other notable changes
* PR titles from the release-note label

Major/Minor Releases

Major Themes
* Add to or delete this section

Other notable improvements
* Add to or delete this section

Experimental Features
* Add to or delete this section

Action Required
* PR titles from the release-note-action-required label

Known Issues
* Add to or delete this section

Provider-specific Notes
* Add to or delete this section

Other notable changes
* PR titles from the release-note label

Work estimates

  • The new munger
    • Owner: @eparis
    • Time estimate: Mostly done
  • Updates to the tool that collects, organizes, publishes and sends release notifications.
    • Owner: @david-mcmahon
    • Time estimate: A few days

Caveats / Considerations

  • As part of the planning and development workflow how can we capture release notes for bigger features? #23070
    • For now contributors should simply use the first PR that enables a new feature by default. We’ll revisit if this does not work well.