commit c0610ba70baef1ab7f2cfa510d48840cec65c94a
author Chris Bracken <cbracken@google.com> Tue May 28 20:05:08 2024 +0000
committer CQ Bot Account <flutter-scoped@luci-project-accounts.iam.gserviceaccount.com> Tue May 28 20:05:08 2024 +0000
tree f88126cd83755794078bc530fa873348d17203a7
parent 4fd341a3b358bc8d3265708f4b301ce37a45b8c5

Use git ref to determine release branch name

This updates the RepoUtils `release_candidate_branch` function to make
use of the incoming git ref, if specified, when looking up which release
candidate branch corresponds to the commit at HEAD.

The previous implementation returned the first branch starting with
"flutter-" that happens to contain the checked out commit SHA. This is
problematic for two reasons:

  * Multiple branches may contain the checked out SHA. In particular, if
    newer release branches have been created since the release at which
    we're building, it's likely they all contain the commit. Previously,
    in that case, we would arbitrarily return the first matching branch.
    Assuming the branches are returned in lexicographic order (probably
    not a safe assumption), older branches will appear earlier in the
    list, meaning we're more likely to select the wrong branch.

  * We're not actually interested in whether a branch *contains* the
    commit at HEAD; we're interested in knowing if the branch has the
    commit at HEAD as *its* HEAD commit.

This updates the function to check that a git ref starting with
"flutter-" is specified and that its HEAD matches the current HEAD
commit.

Background
==========

After renewing and uploading the iOS/macOS signing certificates (a process required once every 5 years), we triggered a release build to test that the new certs were picked up. This generated:

* Top-level release/release_builder build 618:
  https://ci.chromium.org/ui/p/dart-internal/builders/flutter/Mac%20engine_release_builder/618/overview

* Which triggered a macOS engine_v2/engine_v2 build 12070:
  https://ci.chromium.org/ui/p/dart-internal/builders/flutter/Mac%20Production%20Engine%20Drone/12070/overview

* Which generated this macOS host_debug engine_v2/builder build 12082:
  https://ci.chromium.org/ui/p/dart-internal/builders/flutter/Mac%20Production%20Engine%20Drone/12082/infra

Looking at the setup_build/run_recipe output for the top level build (618) we see the correct release candidate ref passed in: refs/heads/flutter-3.18-candidate.18

We see the same release candidate ref in the setup_build/run_recipe output for the macOS engine_v2/engine_v2 build (12070).

However, looking at the third-level macOS host_debug engine_v2/builder build, we see the wrong candidate branch is selected in the kitchen-checkout and exe sections of the recipe_engine/buildbucket mappings: refs/heads/flutter-0.0-candidate.1234

This is due to the flaw in the previous branch selection logic described above.

Bug: b/333426905
Change-Id: I8c8d6b8a3eb4fc69d78c0d04ecc63cd36a963297
Reviewed-on: https://flutter-review.googlesource.com/c/recipes/+/57720
Reviewed-by: Christopher Fujino <fujino@google.com>
Reviewed-by: Zach Anderson <zra@google.com>
Commit-Queue: Chris Bracken <cbracken@google.com>