Change default branch to "main"

[kashifest]

Once the community agrees on the naming, we need to change our default development branch to main, and check that any tools or references to it are changed as well.

CAPI and a couple of provider's repos already did this (CAPA, CAPZ for example)

Partially addresses this.

/kind feature

[kashifest]

Steps

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.

[furkatgofurov7]

/approve

[kashifest]

PRs opened

• Add main branch setting for IPAM project-infra#245
• ⚠️ Add main branch reference #61
• Add main branch reference for IPAM metal3-dev-env#831
• Remove IPAM master branch from prow config project-infra#246

[kashifest]

Once all PR's are merged and we purge the master branch. I'll close this issue.

[Rozzii]

@kashifest I think you can close it now.

[kashifest]

Right. Thanks.