VolumeBinding's Score plugin in enabled by default in v1beta3 and v1 config

[Huang-Wei]

What happened?

Followed up with @alculquicondor, VolumeBinding Score plugin is enabled only when the feature gate VolumeCapacityPriority is enabled:

kubernetes/pkg/scheduler/apis/config/v1beta2/default_plugins.go

Lines 115 to 119 in 43a2bb4

	func applyFeatureGates(config *v1beta2.Plugins) {
	if utilfeature.DefaultFeatureGate.Enabled(features.VolumeCapacityPriority) {
	config.Score.Enabled = append(config.Score.Enabled, v1beta2.Plugin{Name: names.VolumeBinding, Weight: pointer.Int32(1)})
	}
	}

However, with v1beta3 and v1, VolumeBinding Score plugin is no longer feature gated (although its underlying logic is).

What did you expect to happen?

We'd pursue disabling a plugin if the feature gate is disabled. Another thread: #113275 (comment)

How can we reproduce it (as minimally and precisely as possible)?

Run kube-scheduler using a v1beta3 or v1 config, without enabling VolumeCapacityPriority feature gate.

Anything else we need to know?

No response

Kubernetes version

$ kubectl version
# paste output here

Cloud provider

N/A

OS version

# On Linux:
$ cat /etc/os-release
# paste output here
$ uname -a
# paste output here

# On Windows:
C:\> wmic os get Caption, Version, BuildNumber, OSArchitecture
# paste output here

Install tools

Container runtime (CRI) and version (if applicable)

Related plugins (CNI, CSI, ...) and versions (if applicable)

[Huang-Wei]

/sig scheduling

[k8s-ci-robot]

@Huang-Wei: This issue is currently awaiting triage.

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[alculquicondor]

Can we actually do this retroactively?

[pohly]

/cc

[Huang-Wei]

Can we actually do this retroactively?

I think we should as it's a bug in terms of configuration's correctness, although not a bug in the POV of plugin behavior.

cc @ahg-g @liggitt @cofyc

[ahg-g]

hmm, the issue is that the fix will break existing configurations that explicitly set the score plugin in the config while the feature is disabled, although I don't expect anyone to do that, it is safer to just keep it as is and just try to graduate the feature asap.

[Huang-Wei]

that explicitly set the score plugin in the config while the feature is disabled

Although it's pretty rare, but yes, this case will be impacted. And this is the cost of not making things right in the beginning :(

So if we're good on keeping this mistake as-is, I'm gonna close #113706. However, it's uncertain how soon we can graduate VolumeCapacityPriority, it's worth adding comments explaining this is an incorrect pattern so others won't accidentally "copy" the wrong pattern (like @pohly almost used the wrong pattern). WDYT?

[alculquicondor]

+1 on a comment

[Huang-Wei]

/help

TODO: document that it's incorrect to enable VolumeCapacityPriority plugin without regard of its feature gate.

[k8s-ci-robot]

@Huang-Wei:
This request has been marked as needing help from a contributor.

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In response to this:

/help

TODO: document that it's incorrect to enable VolumeCapacityPriority plugin without regard of its feature gate.

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