Add Flatcar Container Linux sysext templates

[sayanchowdhury]

What type of PR is this?
/kind feature

What this PR does / why we need it:

This PR adds a new cluster template for Flatcar based on systemd-sysexts. The advantages of the implementation is that the clusters can directly consume the vanilla Flatcar SIG images, instead of the Flatcar-K8S images built through image-builder.

The PR is currently in draft stage, as I'm looking into adding the tests for the PR but opening it for early comments.

cc @pothos

Special notes for your reviewer:

• cherry-pick candidate

TODOs:

• squashed commits
• includes documentation
• adds unit tests

Release note:

Add new flavor `flatcar-sysext` for Flatcar Container Linux cluster deployments.

[k8s-ci-robot]

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[k8s-ci-robot]

Hi @sayanchowdhury. Thanks for your PR.

I'm waiting for a kubernetes-sigs member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

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[mboersma]

/ok-to-test

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 52.79%. Comparing base (976f893) to head (3861b10).
Report is 44 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4575      +/-   ##
==========================================
+ Coverage   52.66%   52.79%   +0.13%     
==========================================
  Files         273      270       -3     
  Lines       29189    29043     -146     
==========================================
- Hits        15371    15332      -39     
+ Misses      13029    12920     -109     
- Partials      789      791       +2     

☔ View full report in Codecov by Sentry.
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[sayanchowdhury]

/test pull-cluster-api-provider-azure-e2e-optional

[k8s-triage-robot]

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/lifecycle stale

[t-lo]

we have another test scenario in our optional job, if we get flakes for this flatcar test, please file an issue and reach out to @t-lo and @sayanchowdhury and @tormath1 for triage and debugging.

Thank you for the contribution!

@jackfrancis While I do see OWNERS information in the repository would it maybe make sense to start a separate CODEOWNERS document to make it clear who to reach out to regarding individual sub-systems (Ignition / Flatcar support in the case at hand)? I believe this would be helpful for users and even for new contributors.

[mboersma]

/lgtm
/retest
/assign @jackfrancis

[k8s-ci-robot]

LGTM label has been added.

Git tree hash: 0fe9ec5d3f4367f6efb4d3af14679c44e6ee6888

[jackfrancis]

apiversion upgrade test seems to be complaining about 1.27.16, is there some CI version or image promotion housekeeping we need to do to get that test passing?

cc @mboersma

[mboersma]

I didn't realize we needed v1.27.16 images for that test. I'll go populate those in the community gallery and I'll /retest.

[mboersma]

/retest

[mboersma]

/retest
v1.28.10 is in use too, populated now.

[jackfrancis]

/approve

apiversion-upgrade is a non-optional test so if it passes we're g2g

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: jackfrancis

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• OWNERS [jackfrancis]

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[mboersma]

It looks like the switch to community gallery images somehow broke the CAPI upgrade test:

{Machines should remain the same after the upgrade
Expected
    <bool>: false
to be true failed [FAILED] Machines should remain the same after the upgrade
Expected
    <bool>: false
to be true
In [It] at: /home/prow/go/pkg/mod/sigs.k8s.io/cluster-api/[email protected]/e2e/clusterctl_upgrade.go:650 @ 10/31/24 21:32:34.429
}

I'm having trouble seeing what's changed from reading the logs.

Sorry @sayanchowdhury, this doesn't have anything to do with your PR, we'll get it worked out ASAP.

[jackfrancis]

@willie-yao worked on this test recently, he might be able to help

[willie-yao]

Looking into it now. I remember seeing a similar error when implementing the test.

[willie-yao]

@mboersma The only difference I see between the failed Machine and a passed test is that the Machines seem to be failing on Ubuntu 24.04. The Machines are 22.04 post-upgrade in a passed test.

[willie-yao]

The test is also upgrading from 22.04 to 24.04 now in the failed test. It looks like the old Machine comes up, then gets replaced by one with Ubuntu 24.04. Do you know why this may be happening? @mboersma @jackfrancis

[nojnhuh]

The new community gallery images are based on Ubuntu 24.04 while the old Marketplace images are based on 22.04.

I'm reasonably confident the failure isn't related to this PR, so I opened a new issue: #5229

[willie-yao]

This PR looks good, should we just admin-merge it? @nojnhuh

[nojnhuh]

This PR looks good, should we just admin-merge it? @nojnhuh

SGTM

/override pull-cluster-api-provider-azure-apiversion-upgrade

[k8s-ci-robot]

@nojnhuh: Overrode contexts on behalf of nojnhuh: pull-cluster-api-provider-azure-apiversion-upgrade

In response to this:

This PR looks good, should we just admin-merge it? @nojnhuh

SGTM

/override pull-cluster-api-provider-azure-apiversion-upgrade

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[k8s-ci-robot]

@sayanchowdhury: The following tests failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
pull-cluster-api-provider-azure-e2e-aks	3861b10	link	unknown	/test pull-cluster-api-provider-azure-e2e-aks
pull-cluster-api-provider-azure-apiversion-upgrade	3861b10	link	unknown	/test pull-cluster-api-provider-azure-apiversion-upgrade

Full PR test history. Your PR dashboard. Please help us cut down on flakes by linking to an open issue when you hit one in your PR.

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