Change default branch to "main"

[sbueringer]

/kind feature

Describe the solution you'd like
Let's rename our default branch to main. A lot of kubernetes repos already did this (including CAPA and kind for example)

Anything else you would like to add:
I would open the necessary PRs to do this.

[sbueringer]

/assign

[sbueringer]

@jichenjc @hidekazuna

If it's okay for you I would have started implementing this issue after the release. But I'll first have to check what we have to do for that. I expect something like:

• change the default branch of this repo (+ maybe something to do for those with local clones)
• change our config in test-infra from master => main

After I know what to do I would have announced it / asked for feedback via Slack to make sure everybody had a chance to notice, before we do it :)

[jichenjc]

+1 to me , if upstream repo already did so, let's do it

I assume not so much to do as and as you mentioned, need everyone to be aware of this

[sbueringer]

Upstream cluster-api didn't do it yet but CAPA and a lot of other Kubernetes repos, so I just like to get it done :)

[tobiasgiese]

@sbueringer as discussed I will take this task.
/assign

[tobiasgiese]

xref kubernetes-sigs/cluster-api#3280 (comment)

[tobiasgiese]

https://www.kubernetes.dev/resources/rename/

Prerequisites

• Create an issue in your repo to track the branch rename.
  You can paste this checklist in the issue body.

• If you are not a root approver for the repo, assign a root
  approver for approval.

• Once the issue has been approved, send a notice to your SIG's
  mailing list about the potential branch rename.

Changes pre-rename

Make the following changes before renaming the branch the master branch.

Note: There might be additional changes required that have not been
covered in this checklist.

Note: There might be additional information available in the umbrella issue via [kubernetes/org#2222].

Anytime

These changes are non-disruptive and can be made anytime before renaming
the branch.

• If a presubmit or postsubmit prowjob triggers on the master branch
  (branches field of the prowjob), add the main branch to the list
  (see kubernetes/test-infra#20665 for an example).

• If the milestone_applier prow config references the master branch,
  add the main branch to the config (see kubernetes/test-infra#20675 for an example).

• If the branch_protection prow config references the master branch,
  add the main branch to the config.

Just before rename

These changes are disruptive and should be made just before renaming the
branch.

• For periodic prowjobs, or any prowjob that mentions the master branch
  in base_ref, update them to the main branch. Ensure that these changes
  happen in lock-step with the branch rename (jobs triggered in between landing
  these changes and renaming the branch will fail).

  • For bootstrap-based jobs, ensure the branch is explicitly specified,
    e.g. kubernetes/foo=main. kubernetes/test-infra#20667 may eventually
    allow for non-disruptive changes.
  • For pod-utils based jobs, ensure the branch is explicitly specified,
    e.g. base_ref: main. kubernetes/test-infra#20672 may eventually allow
    for non-disruptive changes.

• If a prowjob mentions master in its name, rename the job to not include
  the branch name, e.g. pull-repo-verify-master -> pull-repo-verify.
  status-reconciler should automatically migrate PR status contexts to the
  new job name, and retrigger accordingly, but we have anecdotally found it
  sometimes misses changes.

  • NOTE: our infrastructure doesn't understand the concept of job renames, so
    from the perspective of e.g. https://testgrid.k8s.io the job will appear to
    have lost history and start from scratch.

• If a prowjob calls scripts or code in your repo that explicitly
  reference master, update all references to use main, or auto-detect the
  remote branch

  • e.g. using git to auto-detect

  # for existing clones, update their view of the remote
  git fetch origin
  git remote set-head origin -a
  # for new clones, or those updated as above, this prints "main" post-rename
  echo $(git symbolic-ref refs/remotes/origin/HEAD)

  • e.g. using github's api to auto-detect

  # gh is https://github.com/cli/cli, this will print "main" post-rename
  gh api /repos/kubernetes-sigs/slack-infra | jq -r .default_branch

• If the repo has netlify configured for it, ask a member of the GitHub
  Management Team to rename the master branch to main in the netlify site config.
  It can't be controlled through the netlify config in the repo.

Approval

• Once all non-disruptive tasks have been completed and disruptive tasks
  have been identified, assign the GitHub Management team (@kubernetes/owners)
  for approval.

Rename the default branch

• Rename the default branch from master to main using the GitHub UI
  by following the official instructions.

Changes post-rename

After the default branch has been renamed to main, make the following
changes.

Note: There might be additional changes required that have not been
covered in this checklist.

Prowjobs

• If a prowjob still references the master branch in the branches field,
  remove the master branch (see kubernetes/test-infra#20669 for an example).

Prow config

• If the milestone_applier prow config references the master branch,
  remove it from the config.

• If the branch_protection prow config references the master branch,
  remove it from the config.

Other

• If any docs reference the master branch, update to main
  (URLs will be automatically redirected).

• Ensure that CI and PR tests work fine.

  • If there are any outstanding PRs you can /approve to merge, do so to verify
    that presubmits and postsubmits work as expected

• Trial the local development experience with a pre-rename clone.

  • ensure Github instructions to rename your local branch work
  • consider updating your fork's default remote branch name such that if you
    have git autocompletion enabled, typing ma<tab> will autocomplete to main

• Send a notice about the branch rename to your SIG's mailing list.
  Include the link to the GitHub instructions to rename your local branch.

[tobiasgiese]

Rename was successful.
Will keep this issue open until the Netlify default branch has changed as well (already notified the Kubernetes admins).

[jichenjc]

thanks :)

[tobiasgiese]

Rename was successful. Will keep this issue open until the Netlify default branch has changed as well (already notified the Kubernetes admins).

done via #1032

/close

[k8s-ci-robot]

@tobiasgiese: Closing this issue.

In response to this:

Rename was successful. Will keep this issue open until the Netlify default branch has changed as well (already notified the Kubernetes admins).

done via #1032

/close

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