Testing of Github Merge Queue

[non-fungible-nelson]

https://github.blog/changelog/2023-02-08-pull-request-merge-queue-public-beta/

Testing of merge queue for Github to avoid conflicts going forward.

[macfarla]

I tried merge queue in a test repo - works as expected.

• PR A with no conflicts merged without trouble
• PR B with conflict resulting from PR A was removed from the merge queue
• PR C with conflict resulting from PR A was able to be added to the merge queue - it's still sitting there waiting for the conflict to be resolved
• PR D reverting an earlier PR was merged without trouble
  I still have some unmerged PRs sitting there if anyone else wants to play with it

[macfarla]

Squash commits?
I set the settings in the test repo to match besu - ie allow squash merging. The "add to merge queue" button doesn't show any options around squash commits, and the PR I created with multiple commits did not get squashed. (This commit and the two before it are from the same PR https://github.com/daisy-row/vigilant-octo-umbrella/commit/78576553486c62e44eb17837e870d537ab34d5c6) Not sure if there's something else in Besu repo settings that would make this behave differently.

[macfarla]

Looks like you can choose options when setting up merge queue. Have asked Ry for admin access to the test repo. https://docs.github.com/en/repositories/configuring-branches-and-merges-in-your-repository/configuring-pull-request-merges/managing-a-merge-queue#managing-a-merge-queue

[macfarla]

Now we have merge queue + squash commits - see commits from Feb 21
https://github.com/daisy-row/vigilant-octo-umbrella/commits/main

[macfarla]

added DCO as a required check

[macfarla]

I think we would need to make this change ie add merge_group trigger to CI config

https://docs.github.com/en/repositories/configuring-branches-and-merges-in-your-repository/configuring-pull-request-merges/managing-a-merge-queue#triggering-merge-group-checks-with-github-actions

[macfarla]

DCO strikes again - the DCO that we use https://github.com/tim-actions/dco does not support merge_group event trigger (neither does it support merge events which is why we have this open issue #4837) - we can investigate other dco options (write our own? dcoapp doesn't support merge queue yet either dcoapp/app#199). But DCO has to be a required check at that point, there isn't a separate set of checks for the merge queue.

So for now have turned off merge queue. Back to status quo.

[macfarla]

https://wiki.hyperledger.org/display/BESU/GitHub+Merge+Queue

[macfarla]

#5207

[macfarla]

Merge queue update - I think we have a solution!

Added a separate "dco" check that is triggered by the merge_group event but doesn't check anything #5207 (existing dco check runs on pull_request event as before) - and merge queue is happily running it eg this PR #5209 is merging via the merge queue - and here is the dco job - https://github.com/hyperledger/besu/actions/runs/4402919772/jobs/7710635563