Table of Contents

Release Process #

This page describes the release cadence and process for Thanos project.

We use Semantic Versioning.

NOTE: As Semantic Versioning states all 0.y.z releases can contain breaking changes in API (flags, grpc API, any backward compatibility)

Cadence #

We aim for regular and strict one release per 6 weeks. 6 weeks is counter from first release candidate to another. This means that there is no code freeze or anything like that. We plan to stick to the exact 6 weeks, so there is no rush into being within release (except bug fixes).

No feature should block release.

Additionally, we (obviously) aim for main branch being stable.

We are assigning a release shepherd for each minor release.

Release shepherd responsibilities:

  • Perform releases (from first RC to actual release).
  • Announce all releases on all communication channels.
ReleaseTime of first RCShepherd (GitHub handle)
v0.27.02022.06.21@wiardvanrij and @matej-g
v0.25.02022.03.01@bwplotka and @matej-g
v0.21.02021.05.28@metalmatze and @onprem

For maintainers: Cutting individual release #

Process of releasing a minor Thanos version:

  1. Release v<major>.<minor+1>.0-rc.0
  2. If after 3 work days there is no major bug, release v<major>.<minor>.0
  3. If within 3 work days there is major bug, let’s triage it to fix it and then release v<major>.<minor>.0-rc.++ Go to step 2.
  4. Do patch release if needed for any bugs afterwards. Use same release-xxx branch and migrate fixes to main.

How to release a version #

Release is happening on separate release-<major>.<minor> branch.

Prepare the release branch #

Prepare branch release-<major>.<minor> that will start minor release branch and prepare changes to cut release.

Push the created branch to origin (Thanos repository) to be able to make your PR with the changes against this branch later.

$ git push origin release-<major>.<minor>

For release candidate, reuse the same branch and rebase it on every candidate until the actual release happens.

Indicate that a release is in progress #

  1. Create small PR to main (!) to cut CHANGELOG. This helps to maintain new changelog on main. Add entry to CHANGELOG indicating release in progress. This reduces risk for the new PRs to add changelog entries to already released release.

  2. Update VERSION file to version one minor version higher than the released one and dev suffix. This allows CI to build Thanos binary with the version indicating potential next minor release, showing that someone uses non-released binary (which is fine, just better to know this!).

Feel free to mimic following PR:

Prepare the release #

  1. Create a branch based on the release branch. You will use this branch to include any changes that need to happen as a part of ‘cutting’ the release. Follow the steps below and commit and resulting changes to this branch.

  2. Double check and update CHANGELOG file. Note that should only document changes relevant to users of Thanos, including external API changes, bug fixes, performance improvements, and new features. Do not document changes of internal interfaces, code refactorings and clean-ups, changes to the build process, etc. People interested in these are asked to refer to the git history. Format is described in

    • The whole release from release candidate rc.0 to actual release should have exactly the same section. We don’t separate what have changed between release candidates.
  3. Double check backward compatibility:

    1. In case of version after v1+.y.z, double check if none of the changes break API compatibility. This should be done in PR review process, but double check is good to have.
    2. In case of v0.y.z, document all incompatibilities in changelog.
  4. Double check metric changes:

    1. Note any changes in the changelog
    2. If there were any changes then update the relevant alerting rules and/or dashboards since thanos-mixin is part of the repository now
  5. (Applies only to minor, non-rc release) Update website’s hugo.yaml to have correct links for new release ( add 0.y.z: "/:sections/").

  6. (Applies only to minor, non-rc release) Update tutorials:

    1. Update the Thanos version used in the tutorials manifests to use the latest version.
    2. In case of any breaking changes or necessary updates adjust the manifests so the tutorial stays up to date.
    3. Update the scripts/ script if needed.
  7. Set the version in VERSION to reflect the tag you are going to make.

    • If you are going to tag v<major>.<minor>.0-rc.0, this exact tag should be in VERSION. Example: v0.25.2-rc.0/VERSION
  8. Open a PR with any changes resulting from the previous steps against the release branch and ask the maintainers to review it.

Tag and publish the release #

  1. After review and obtaining (an) approval(s), merge the PR and after this tag a version:

    tag=$(cat VERSION)
    git tag -s "v${tag}" -m "v${tag}"
    git push origin "v${tag}"

    Signing a tag with a GPG key is appreciated, but in case you can’t add a GPG key to your GitHub account using the following procedure, you can replace the -s flag by -a flag of the git tag command to only annotate the tag without signing.

    Please make sure that you are tagging the merge commit because otherwise GitHub’s UI will show that there were more commits after your release.

  2. Once a tag is created and pushed, immediately create a GitHub Release using the UI for this tag, as otherwise CircleCI will not be able to upload tarballs for this tag. Go to the releases page of the project, click on the Draft a new release button and select the tag you just pushed. Describe release and post relevant entry from changelog. Click Save draft rather than Publish release at this time. (This will prevent the release being visible before it has got the binaries attached to it.) In case you did not manage to create the draft release before CircleCI run is finished (it will fail on the artifacts upload step in this case), you can re-trigger the run manually from the CircleCI dashboard after you created the draft release.

  3. You are also encouraged to include a list of (first time) contributors to the release. You can do this by clicking on Auto-generate release notes, which will generate this section for you (edit the notes as required to remove unnecessary parts).

  4. Once tarballs are published on release page, you can click Publish and release is complete.

Completing the release #

  1. Announce the release on the #thanos Slack channel. You are also encouraged to announce the new release on any Thanos social media accounts, such as Twitter (the credentials are available via Thanos’ Keybase team which includes all maintainers).

  2. Pull commits from release branch to main branch for non rc releases. Make sure to not modify VERSION, it should be still pointing to version+1-dev (TODO to automate this)

  3. After releasing a major version, please cut a release for kube-thanos as well. Make sure all the flag changes are reflected in the manifests. Otherwise, the process is the same, except we don’t have rc for the kube-thanos. We do this to make sure we have compatible manifests for each major versions.

  4. Merge release-<major>.<minor> branch back to main. This is important for Go modules tooling to make release tags reachable from main branch.

    • Create merge-release-<major>.<minor>-to-main branch from release-<major>.<minor> branch locally
    • Merge upstream main branch into your merge-release-<major>.<minor>-to-main and resolve conflicts
    • Open a PR for merging your merge-release-<major>.<minor>-to-main branch against main
    • Once approved, merge the PR by using “Merge” commit.
      • This can either be done by temporarily enabling “Allow merge commits” option in “Settings > Options”.
      • Alternatively, this can be done locally by merging merge-release-<major>.<minor>-to-main branch into main, and pushing resulting main to upstream repository. This doesn’t break main branch protection, since PR has been approved already, and it also doesn’t require removing the protection.

Pre-releases (release candidates) #

The following changes to the above procedures apply:

  • In line with Semantic Versioning, append something like -rc.0 to the version (with the corresponding changes to the tag name, the release name etc.).
  • Tick the This is a pre-release box when drafting the release in the GitHub UI.
  • Still update, but when you cut the final release later, merge all the changes from the pre-releases into the one final update.

Found a typo, inconsistency or missing information in our docs? Help us to improve Thanos documentation by proposing a fix on GitHub here ❤️