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Releases

This document describes the Mimir release process as well as release shepherd responsibilities. Release shepherds are chosen on a voluntary basis.

Release schedule

A new Grafana Mimir release is cut approximately every 6 weeks. The following table contains past releases and tentative dates for upcoming releases:

Version Date Release shepherd
2.0.0 2022-03-20 Marco Pracucci
2.1.0 2022-05-16 Johanna Ratliff
2.2.0 2022-06-27 Oleg Zaytsev
2.3.0 2022-08-08 Tyler Reid
2.4.0 2022-09-19 To be announced
2.5.0 2022-10-31 To be announced

Release shepherd responsibilities

The release shepherd is responsible for an entire minor release series, meaning all pre- and patch releases of a minor release. The process formally starts with the initial pre-release, but some preparations should be made a few days in advance.

  • We aim to keep the main branch in a working state at all times. In principle, it should be possible to cut a release from main at any time. In practice, things might not work out as nicely. A few days before the pre-release is scheduled, the shepherd should check the state of main branch. Following their best judgement, the shepherd should try to expedite bug fixes that are still in progress but should make it into the release. On the other hand, the shepherd may hold back merging last-minute invasive and risky changes that are better suited for the next minor release.
  • There may be some actions left to address when cutting this release. The release shepherd is responsible for going through TODOs in the repository and verifying that nothing is that is due this release is forgotten.
  • On the planned release date, the release shepherd cuts the first pre-release (using the suffix -rc.0) and creates a new branch called release-<major>.<minor> starting at the commit tagged for the pre-release. In general, a pre-release is considered a release candidate (that's what rc stands for) and should therefore not contain any known bugs that are planned to be fixed in the final release.
  • With the pre-release, the release shepherd is responsible for coordinating or running the release candidate in any end user production environment for at least 1 week. This is typically done at Grafana Labs.
  • If regressions or critical bugs are detected, they need to get fixed before cutting a new pre-release (called -rc.1, -rc.2, etc.).

See the next section for details on cutting an individual release.

How to cut an individual release

Branch management and versioning strategy

We use Semantic Versioning.

We maintain a separate branch for each minor release, named release-<major>.<minor>, e.g. release-1.1, release-2.0.

The usual flow is to merge new features and changes into the main branch and to merge bug fixes into the latest release branch. Bug fixes are then merged into main from the latest release branch. The main branch should always contain all commits from the latest release branch. As long as main hasn't deviated significantly from the release branch, new commits can also go to main, followed by cherry-picking them back into the release branch. See Cherry-picking changes into release branch.

Maintaining the release branches for older minor releases happens on a best effort basis.

Show that a release is in progress

This helps ongoing PRs to get their changes in the right place, and to consider whether they need cherry-picking into release branch.

  1. Make a PR to update CHANGELOG.md on main
    • Add a new section for the new release so that ## main / unreleased is blank and at the top.
    • The new section should say ## x.y.0-rc.0.
  2. Get this PR reviewed and merged.
  3. Comment on open PRs with a CHANGELOG entry to rebase on main and move the CHANGELOG entry to the top under ## main / unreleased

Prepare your release

For a new major or minor release, create the corresponding release branch based on the main branch. For a patch release, work in the branch of the minor release you want to patch.

To prepare a release branch, first create new release branch (release-X.Y) in the Mimir repository from the main commit of your choice, and then do the following steps on a temporary branch (prepare-release-X.Y) and make a PR to merge said branch into the new release branch (prepare-release-X.Y -> release-X.Y):

  1. Make sure you've a GPG key associated with your GitHub account (git tag will be signed with that GPG key)
    • You can add a GPG key to your GitHub account following this procedure
  2. Update the version number in the VERSION file to say X.Y-rc.0
  3. Update CHANGELOG.md
    • Ensure changelog entries for the new release are in this order:
      • [CHANGE]
      • [FEATURE]
      • [ENHANCEMENT]
      • [BUGFIX]
    • Run ./tools/release/check-changelog.sh LAST-RELEASE-TAG...main and add any missing PR which includes user-facing changes.
    • check-changelog.sh script also reports number of PRs and authors on the top. Note the numbers and include them in the release notes in GitHub.

Once your release preparation PR is approved, merge it to the release-X.Y branch, and continue with publishing.

Write release notes document

Each Grafana Mimir release comes with a release notes that is published on the website. This document is stored in docs/sources/release-notes/, and contains following sections:

  • Features and enhancements
  • Upgrade considerations
  • Bug fixes

Please write a draft release notes PR, and get it approved by Grafana Mimir's Product Manager (or ask PM to send PR with the document). Make sure that release notes document for new version is available from the release branch, and not just main. See PR 1848 for an example PR.

Publish a release candidate

To publish a release candidate:

  1. Do not change the release branch directly; make a PR to the release-X.Y branch with VERSION and any CHANGELOG changes.
    1. Ensure the VERSION file has the -rc.X suffix (X starting from 0).
  2. After merging your PR to the release branch, git tag the new release (see How to tag a release) from the release branch.
  3. Wait until the CI pipeline succeeds (once a tag is created, the release process through GitHub Actions will be triggered for this tag).
  4. Merge the release branch release-x.y into main (see Merging release branch into main)
  5. Create a pre-release on GitHub. See Creating release on GitHub.

Creating release on GitHub

  1. Go to https://github.com/grafana/mimir/releases/new to start a new release on GitHub (or click "Draft a new release" at https://github.com/grafana/mimir/releases page.)
  2. Select your new tag, use Mimir <VERSION> as Release Title. Check that "Previous tag" next to "Generate release notes" button shows previous Mimir release. Click "Generate release notes" button. This will pre-fill the changelog for the release. You can delete all of it, but keep "New Contributors" section and "Full Changelog" link for later.
  3. Release description consists of:
    • "This release contains XX contributions from YY authors. Thank you!" at the beginning. You can find the numbers by running ./tools/release/check-changelog.sh LAST-RELEASE-TAG...NEW-RELEASE-TAG. As an example, running the script with mimir-2.0.0...mimir-2.1.0 argument reports Found 417 PRs from 47 authors..
    • After contributor stats, please include content of the release notes document created previously.
    • After release notes, please copy-paste content of CHANGELOG.md file since the previous release.
    • After CHANGELOG, please include "New Contributors" section and "Full Changelog" link at the end. Both were created previously by "Generate release notes" button in GitHub UI.
  4. Build binaries with make BUILD_IN_CONTAINER=true dist and attach them to the release (building in container ensures standardized toolchain).

Publish a stable release

Note: Technical documentation is automatically published on release tags or release branches with a corresponding release tag. The workflow that publishes documentation is defined in publish-technical-documentation-release.yml.

To publish a stable release:

  1. Do not change the release branch directly; make a PR to the release-X.Y branch with VERSION and any CHANGELOG changes.
    1. Ensure the VERSION file has no -rc.X suffix
    2. Update the Mimir version in the following locations:
      • operations/mimir/images.libsonnet (_images.mimir and _images.query_tee fields)
      • operations/mimir-rules-action/Dockerfile (grafana/mimirtool image tag)
  2. Update dashboard screenshots
    1. Run make mixin-screenshots
    2. Review all updated screenshots and ensure no sensitive data is disclosed
    3. Open a PR
  3. After merging your PR to the release branch, git tag the new release (see How to tag a release) from the release branch.
  4. Wait until the CI pipeline succeeds (once a tag is created, the release process through GitHub Actions will be triggered for this tag)
  5. Create a release on GitHub. This is basically a copy of release notes from pre-release version, with up-to-date CHANGELOG (if there were any changes in release candidates).
  6. Merge the release branch release-x.y into main (see Merging release branch into main)
  7. Open a PR to add the new version to the backward compatibility integration test (integration/backward_compatibility_test.go)
  8. Publish dashboards (done by a Grafana Labs member)
    1. Login to https://grafana.com with your Grafana Labs account
    2. Open https://grafana.com/orgs/grafana/dashboards
    3. For each dashboard at operations/mimir-mixin-compiled/dashboards:
      1. Open the respective dashboard page
      2. Click "Revisions" tab
      3. Click "Upload new revision" and upload the updated .json

How to tag a release

Every release is tagged with mimir-<major>.<minor>.<patch>, e.g. mimir-2.0.0. Note the mimir- prefix, which we use to specifically avoid the Go compiler recognizing them as version tags. We don't want compatibility with Go's module versioning scheme, since it would require us to keep each major version's code in its own directory beneath the repository root, f.ex. v2/. We also don't provide any API backwards compatibility guarantees within a single major version.

You can do the tagging on the commandline:

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

Cherry-picking changes into release branch

To cherry-pick a change (commit) from main into release branch, please do the following:

$ git checkout release-X.Y                   # Start with the release branch
$ git checkout -b cherry-pick-pr-ZZZ         # Create new branch for cherry-picking
$ git cherry-pick -x <commit ID>             # Cherry pick the change using -x option to add original commit ID to the message
$ git push origin cherry-pick-pr-ZZZ         # Push branch to GitHub.

After pushing branch to GitHub, you can create the PR by opening https://github.com/grafana/mimir/pull/new/cherry-pick-pr-ZZZ link. Make sure to set release-X.Y as the base branch, into which PR should be merged. After PR with cherry-picked commit is reviewed, do a standard "Squash & Merge" commit that we use in Mimir. Keep the commit message suggested by GitHub, which is a combination of original commit message, original PR number, new PR number and cherry-picked commit hash. GitHub will properly attribute you and also original commit author as contributors to this change, and will also link to original commit in the UI.

Merging release branch into main

To merge a release branch release-X.Y into main, please do the following:

  • Create merge-release-X.Y-to-main branch from the upstream main branch locally
  • Merge the release-X.Y branch into your merge-release-X.Y-to-main branch and resolve conflicts
    • Keep the main's VERSION file contents
  • Make a PR for merging your merge-release-X.Y-to-main branch into main
  • Once approved, merge the PR with a Merge commit through one of the following strategies:
    • Temporarily enable "Allow merge commits" option in "Settings > Options"
    • Locally merge the merge-release-X.Y-to-main branch into main, and push the changes to main back to GitHub. This doesn't break main branch protection, since the PR has been approved already, and it also doesn't require removing the protection.