tracking: switch default branch to main

[BenTheElder]

see: https://k8s.dev/rename, kubernetes/org#2222

Checklist below added from kubernetes/community@198374d

Prerequisites

• Ensure that your repo has low PR volume (<20 open PRs) and
  less number of periodic jobs. The branch rename will re-trigger
  prow on all open PRs, which will cause a huge spike in the CI load.

  • We have zero periodic jobs directly consuming this repo
  • We have < 10 PRs open now (17:14 PST 2021-03-15)

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

  • This is the issue

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

  • I am a root approver

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

  • Notice here: https://groups.google.com/g/kubernetes-sig-testing/c/Gi0A_TJsP7A

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.

Anytime

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

• If a prowjob triggers on the master branch (branches field
  of the prowjob), add the main branch to the list
  (see [prep kubernetes/org jobs for default branch rename kubernetes/test-infra#20665] for an example).

  • N/A: we only use one branch and don't specify it wherever possible

• If the [milestone_applier] prow config references the master branch,
  add the main branch to the config (see [Prep kubernetes/k8s.io for default branch rename kubernetes/test-infra#20675] for an example).

  • N/A: we don't use milestone applier

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

  • N/A: we only use the automatic branch protection based on prowjobs

Just before rename

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

• If a prowjob mentions the master branch in base_ref,
  update it to the main branch. For a periodic job, ensure that
  the branch is renamed between periodic job runs.

  • N/A we have no jobs that mention branches of this repo.

• If a prowjob mentions master in its name, rename the job to
  to not include the branch name. [status-reconciler] should automatically
  migrate the PR status contexts to the new job name but this has not been tested yet.
  The job with the new name will also appear as a different job in Testgrid.

  • N/A we have no jobs that mention branches of this repo.

• If a prowjob calls scripts or code in your repo that explicitly
  reference master, update all references to use main.

  • N/A we don't do this.

• 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.

  • We will need to do this.
  • This is done.

Approval

• Once all non-disruptive tasks have been completed and disruptive tasks
  have been identified, assign the GitHub Management team ([@kubernetes/owners])
  for approval.
  • tracking: switch default branch to main #2120 (comment) (see below)

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 [Update kubernetes/org job configs post default-branch-rename kubernetes/test-infra#20669] for an example).
  • N/A we have no jobs that mention branches of this repo.

Prow config

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

  • N/A we don't use milestone_applier here

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

  • N/A we don't have any repo specific branch_protection config (just the automated standard configuration)

Other

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

  • This is done.

• Ensure that CI and PR tests work fine.

  • Look fine so far.

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

  • Nothing in our development experience is branch specific, I just needed to switch from master to main as expected.

• 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].

/assign

[BenTheElder]

went through the current checklist, discussing some feedback in slack here: https://kubernetes.slack.com/archives/C1TU9EB9S/p1615487742145000

[BenTheElder]

will follow up further next week (I am unavailable friday, and it seems best to not try to switch this on a friday anyhow)

[BenTheElder]

Went through the checklist.

We need to send the mailinglist notice, and we'll need help from GitHub management to update Netlify. The rest should be fine.

Will aim to do this Tomorrow.

[BenTheElder]

• Sent notice to the mailinglist
• Updated checklist
• Reached out to @kubernetes/owners in #github-management slack https://kubernetes.slack.com/archives/C01672LSZL0/p1615931201001700

[mrbobbytables]

/approve 👍

[spiffxp]

/assign @kubernetes/owners

[spiffxp]

Ah right. Different org

[BenTheElder]

/assign @kubernetes/owners

This is one of the things I have in kubernetes/community#5636, that's not possible.

[BenTheElder]

Cleaned up references in #2137. After merge we can see https://kind.sigs.k8s.io/ is at b30f419 so the netlify settings worked as well.

[BenTheElder]

Left some more feedback kubernetes/community#5636 (comment)

And updated the mailinglist. This is done. Thanks all.