Assess version markers used in release-branch job configs

[justaugustus]

Version markers are text files stored in the root of various GCS buckets:

• CI: https://gcsweb.k8s.io/gcs/kubernetes-release-dev/ci
• Release: https://gcsweb.k8s.io/gcs/kubernetes-release/release

They represent the results of different types of Kubernetes build jobs and act as sort of a public API for accessing builds. One can see them leveraged in extraction strategies for e2e tests, release engineering tooling, and user-created scripts.

Unfortunately, the way certain version markers are generated and utilized can at best be confusing, and at worst, disruptive.

There are a variety of problems, some of which are symptoms of the other ones...

Generic version markers are not explicit

We publish a set of additional generic version markers:

• k8s-master
• k8s-beta
• k8s-stable1
• k8s-stable2
• k8s-stable3

Depending on the point in the release cycle, the meaning of these markers can
change.

• k8s-master always points to the version on master.
• k8s-beta may represent:
  • masters build version (pre-branch cut)
  • a to-be-released build version (post-branch cut)
  • a recently released build version (post-release)

Knowing what these markers mean at any one time presumes knowledge of the
build/release process or a correct interpretation of the
Kubernetes versions doc,
which has frequently been out of date and lives in a low-visibility location.

Manually created jobs using generic version markers can be inaccurate

Non-generated jobs using generic version markers do not get the same level of
scrutiny as ones that are generated via
releng/test_config.yaml.

This leads to inaccuracies between the versions presumed to be used in test
and the versions that may be displayed in testgrid.

ci-kubernetes-e2e-gce-beta-stable1-gci-kubectl-skew is a great example:

https://github.com/kubernetes/test-infra/blob/96e08f4be2a86189f59c72055785f817ac346d30/config/jobs/kubernetes/sig-cli/sig-cli-config.yaml#L85-L112

All variants of that prowjob have landed on the sig-release-job-config-errors
dashboard for various misconfiguration issues that are the result of generic
version markers.

---

I'd like to establish a rough plan of record to continue iteratively fixing some of these issues.

Plan of record

• (Update generated tests to use latest-x.y version markers test-infra#15564) Use explicit (latest-x.y) version markers in generated jobs
• (releng: Publish fast builds to a separate subdirectory test-infra#18290, push-build: Support pushing fast builds to a /fast subdirectory release#1389) Publish fast builds to separate subdirectory to prevent collisions
• ([WIP] releng: Add stable4 and remove beta generated jobs test-infra#18169) Add a new stable4 field to the kubernetes version lists in releng/test_config.yaml to remove confusion around jobs with beta in their name
• Refactor any non-generated jobs using generic version markers
• Refactor any config-forked release jobs using generic version markers
• Refactor any jobs using fork-per-release-generic-suffix: "true" annotations
• Disable usage of fork-per-release-generic-suffix: "true" annotations
• (sig-release: Add doc on version markers (migrated from k/test-infra) community#5268, docs: Add tombstone for Kubernetes version markers test-infra#19686) Rewrite the Kubernetes versions doc and put it in a more visible location
• Refactor releng/test_config.yaml to remove references to generic versions (e.g., prefer ci-kubernetes-e2enode-ubuntu1-latest-1-19-gkespec over ci-kubernetes-e2enode-ubuntu1-k8sbeta-gkespec)

---

Previous Issues

linux/amd64 version markers are colliding with cross builds

(Fixed in kubernetes/test-infra#18290.)

"Fast" (linux/amd64-only) builds run every 5 minutes, while cross builds run
every hour.
They also write to the same version markers (latest.txt,
latest-<major>.txt, latest-<major>.<minor>.txt).

The Kubernetes build jobs have a mechanism for checking if a build already
exists and will exit early to save on test cycles.

What this means is if a "fast" build has already happened for a commit, then
the corresponding cross build will exit without building.

This has been happening pretty consistently lately, so cross build consumers
are using much older versions of Kubernetes than intended.

(Note that this condition only happens on master.)

Cross builds are stored in a separate GCS bucket

(Fixed in kubernetes/test-infra#14030.)

This makes long-term usage of cross builds a little more difficult, since
scripts utilizing version markers tend to consider only the version marker
filename, while the GCS bucket name remains unparameterized.

Generated jobs may not represent intention

(Fixed in kubernetes/test-infra#15564.)

As the generic version markers can shift throughout the release cycle, every
time we regenerate jobs, they may not represent what we intend to test.

The best examples of this are pretty much every job using the k8s-beta
version marker, and more specifically, skew and upgrade jobs.

bazel version markers appear to be unused

(Fixed in kubernetes/test-infra#15612.)

ref: kubernetes/test-infra#15106

/assign
/area release-eng
/priority important-longterm
/milestone v1.17

[tpepper]

/cc

[justaugustus]

To respond to @spiffxp's comment on the Branch Management issue:

I would suggest that branch management is the role that should handle "what 'channel' (beta/stable1/stable2/stable3) corresponds to which version?"

Agreed. Now codified in the Branch Management handbook.

• the beta channel should only exist after the release-1.y branch is cut, and be unused after the v1.y.0 release is cut (aka during the period that builds being cut have the word beta in them, and the branch manager is running branchff and handling cherry-picks prior to the .0 release)
• the stableN versions are moved forward after the v1.y.0 release is cut, so that stable1 refers to v1.y.0, the most recent stable release, stable2 refers to v1.y-1.0, the previous stable release, etc.
• release teams have forgotten to do this last part since 1.11 (ref: ref: kubernetes/test-infra#13577 (comment)), so we're in a state where the channels don't mean what they should

other ideas include:

• cut release-1.y super early, but branchff at a significantly reduced cadence
  ref: kubernetes/test-infra#13577 (comment)

I liked this idea and actually mentioned this to @tpepper after bumping into kubernetes/test-infra#15514.

My thought here is that creating the new release branch jobs immediately after the final patch release would result in turning down CI on the last-supported branch way sooner and giving time to watch the new release branch jobs stability.

This comes at the cost of more branch fast-forwards and more cherry picks.

Do we think that's worth it?

• decide we don't like the stableN nomenclature at all, and adjust job configs and tooling appropriately (we liked this idea in https://groups.google.com/d/msg/kubernetes-sig-release/ABLP6LHIL7s/0RHWTUd9AQAJ but it proved to be trickier to implement than we had hoped (ref: kubernetes/test-infra#12516))

I'm not a fan of this nomenclature, especially because it has consistently caused confusion and inconsistency around what's under test at one period in the release cycle.

Are there any glaring things that we'd need to look out for going down this route?

[spiffxp]

This comes at the cost of more branch fast-forwards and more cherry picks.

I don't think it would cause more cherry-picks? Those don't start happening until after code freeze.

I was envisioning that alpha's would get cut off of the release-1.y branch with this approach, and that master's version wouldn't bump until after code freeze. This is different than today, where master's version bumps as soon as the release branch is cut.

Are there any glaring things that we'd need to look out for going down this route?

We'll "lose" historical data for jobs on our dashboards (testgrid, triage, velodrome, etc), since none of them comprehend job renames or moves. Early in the release cycle is probably the best time to induce such a gap.

Outside of that I suspect it's not glaring things, just lots of tiny renames. @Katharine might be able to better explain what prevented us from moving ahead with the rename in kubernetes/test-infra#12516.

[justaugustus]

I don't think it would cause more cherry-picks? Those don't start happening until after code freeze.

@spiffxp -- Good point. This was mushy brain from triaging other stuff.

We'll "lose" historical data for jobs on our dashboards (testgrid, triage, velodrome, etc), since none of them comprehend job renames or moves. Early in the release cycle is probably the best time to induce such a gap.

I think I'm fine with losing some historical data if it leads to ease of management for the team over time.

@kubernetes/release-engineering -- What are your thoughts on this?

[justaugustus]

Some discussion in Slack here: https://kubernetes.slack.com/archives/C09QZ4DQB/p1576104279099300
...and I'm poking at the version markers and release job generation here: kubernetes/test-infra#15564

[justaugustus]

Here's another instance of wrestling with version markers being a general nightmare: kubernetes/test-infra#15875

That PR should've been at most a few commits.

This cycle I'm going to be looking at renaming the release-branch jobs that reference beta,stable{1,2,3} and removing the generic suffix annotations. That should be an easy-ish way to get started.

From there, we'll need to look at refactoring generate_tests.py and test_config.yaml.

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[justaugustus]

/reopen
My old friend continues in kubernetes/test-infra#28079...

[k8s-ci-robot]

@justaugustus: Reopened this issue.

In response to this:

/reopen
My old friend continues in kubernetes/test-infra#28079...

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[justaugustus]

k8s-beta rears it head again in the 1.26 release.
See this unmerged PR as an example of fixes: kubernetes/test-infra#26028

@xmudrii is on the right track by opening this issue for k8s-stable4 marker support as a stopgap: #2094

I'm happy for someone else to attempt closing this, but it may just as well make sense for me to tackle given the context.

[justaugustus]

This plan in the description may be still the right path forward, but take caution and ask questions as it's been a while since I've updated it.

Plan of record

• (Update generated tests to use latest-x.y version markers test-infra#15564) Use explicit (latest-x.y) version markers in generated jobs
• (releng: Publish fast builds to a separate subdirectory test-infra#18290, push-build: Support pushing fast builds to a /fast subdirectory release#1389) Publish fast builds to separate subdirectory to prevent collisions
• ([WIP] releng: Add stable4 and remove beta generated jobs test-infra#18169) Add a new stable4 field to the kubernetes version lists in [releng/test_config.yaml][test_config.yaml] to remove confusion around jobs with beta in their name
• Refactor any non-generated jobs using generic version markers
• Refactor any config-forked release jobs using generic version markers
• Refactor any jobs using fork-per-release-generic-suffix: "true" annotations
• Disable usage of fork-per-release-generic-suffix: "true" annotations
• (sig-release: Add doc on version markers (migrated from k/test-infra) community#5268, docs: Add tombstone for Kubernetes version markers test-infra#19686) Rewrite the Kubernetes versions doc and put it in a more visible location
• Refactor [releng/test_config.yaml][test_config.yaml] to remove references to generic versions (e.g., prefer ci-kubernetes-e2enode-ubuntu1-latest-1-19-gkespec over ci-kubernetes-e2enode-ubuntu1-k8sbeta-gkespec)

[xmudrii]

@justaugustus -- I'd be happy to help with this! Let me take a look into the current situation and then we can sync about this if needed.

[cici37]

I would be happy to help with this work. Please let me know if help is needed :)

[justaugustus]

Sounds good. Please work together on this, Cici + Marko!
/assign @cici37 @xmudrii
/unassign

[justaugustus]

(Linking the k8s-stable4 issue that @xmudrii opened: #2094)