Allow bootstrap to use default remote branch

[spiffxp]

I'm on the fence about whether we should do this, since we consider bootstrap to be migrated.

Many bootstrap jobs use --repo=org_name/repo_name=master when what they really mean is "use the remote's default branch"

$ ag \\-\\-repo= | grep =master | wc -l
      98

Unfortunately --repo=org_name/repo_name will default to master rather than detecting the default branch

$ ag \\-\\-repo= | grep -v master | grep -v PULL_REFS | grep -v =release | wc -l
     100

We need to either:

• solve for pod-utils (ref: Allow pod-utils / clonerefs to use default remote branch #20667) and insist jobs migrate to it
• OR drop the =master bit and update bootstrap to detect the default remote branch

/sig testing
/area jobs
/area bootstrap
/sig release
(a lot of the latter case is for k8s.io/release)
/wg naming
since this is in support of kubernetes/org#2222

[BenTheElder]

if the patch is relatively small, the utility of unblocking this migration is higher than gating it on migrating off of bootstrap

[fejta-bot]

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/lifecycle stale

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/lifecycle rotten

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/close

[k8s-ci-robot]

@fejta-bot: Closing this issue.

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/close

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[spiffxp]

/reopen
/remove-lifecycle rotten

An update on where we're at since this issue was first opened.

In the past ~6 months:

• the number of jobs referencing master explicitly has gone down from 98 to 32
• the number of jobs referencing no branch (and thus get master implicitly) has gone down from 102 to 90

At this point I'm ambivalent about whether it would be better to:

• modify bootstrap to support "no branch == default branch"
• explicitly regex =master to everything using bootstrap's --repo=org/repo syntax, to make it extra clear what needs to be regex'ed in lock step

$ git checkout $(git rev-list -n 1 --first-parent --before=2021-01-29 master)
$ rg \\-\\-repo= config/jobs | grep =master | wc -l
      98
$ rg \\-\\-repo= config/jobs | grep -vE 'master|PULL_REFS|=(release|main)' | wc -l
      102

$ git checkout master
$ rg \\-\\-repo= config/jobs | grep =master | wc -l
      32
$ rg \\-\\-repo= config/jobs | grep -vE 'master|PULL_REFS|=(release|main)' | wc -l
      90

[k8s-ci-robot]

@spiffxp: Reopened this issue.

In response to this:

/reopen
/remove-lifecycle rotten

An update on where we're at since this issue was first opened.

In the past ~6 months:

• the number of jobs referencing master explicitly has gone down from 98 to 32
• the number of jobs referencing no branch (and thus get master implicitly) has gone down from 102 to 90

At this point I'm ambivalent about whether it would be better to:

• modify bootstrap to support "no branch == default branch"
• explicitly regex =master to everything using bootstrap's --repo=org/repo syntax, to make it extra clear what needs to be regex'ed in lock step

$ git checkout $(git rev-list -n 1 --first-parent --before=2021-01-29 master)
$ rg \\-\\-repo= config/jobs | grep =master | wc -l
     98
$ rg \\-\\-repo= config/jobs | grep -vE 'master|PULL_REFS|=(release|main)' | wc -l
     102

$ git checkout master
$ rg \\-\\-repo= config/jobs | grep =master | wc -l
     32
$ rg \\-\\-repo= config/jobs | grep -vE 'master|PULL_REFS|=(release|main)' | wc -l
     90

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[spiffxp]

/milestone v1.23

[spiffxp]

/milestone v1.24

[spiffxp]

/priority important-longterm

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/lifecycle stale

[k8s-triage-robot]

The Kubernetes project currently lacks enough active contributors to adequately respond to all issues and PRs.

This bot triages issues and PRs according to the following rules:

• After 90d of inactivity, lifecycle/stale is applied
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/lifecycle rotten

[BenTheElder]

I bias towards energy on bootstrap -> podutils instead, I'm not sure we should reduce friction on bootstrap.py, it's really too bad we're still using this thing.

[BenTheElder]

We're going to focus on eliminating bootstrap instead since it is long deprecated and poorly integrated into prow.