ignore 0 replica check

[congcongke]

What type of PR is this?

/kind bug

What this PR does / why we need it

Scale to 0 is not worked when rolling update is enabled. Skip the related check should be considered.

Which issue(s) this PR fixes

Fixes #

Special notes for your reviewer

Does this PR introduce a user-facing change?

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: congcongke / name: zhanweidu (868a712)

[k8s-ci-robot]

Hi @congcongke. Thanks for your PR.

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[yankay]

/ok-to-test

[kerthcet]

I think it's not related between the scaling-to-zero and rolling update configuration. What you mean here is once replicas == 0, the maxUnavailable and maxSurgeValue could both be zero, however, it's not.

[congcongke]

https://github.com/kubernetes-sigs/lws/blob/da1267b252e17fe795cbc41249a43eb9d52cbca5/pkg/webhooks/leaderworkerset_webhook.go#L160C37-L160C67

Let's consider the case: replica = 0, maxUnavailable = 25% and maxSurge = 20%.
Then maxUnavailableValue will be 0 and maxSurge will be 0 as the calculated as above. Then admission webhook forbid this operation.

[kerthcet]

Sorry, I forgot the value is calculated from the replicas. Let's add a webhook test to make sure it works with replicas==0.

[Edwinhr716]

/lgtm
This makes sense to me, will leave to @kerthcet for approval. Can you do the EasyCLA authorization @congcongke?

[congcongke]

/lgtm This makes sense to me, will leave to @kerthcet for approval. Can you do the EasyCLA authorization @congcongke?

I tried to authorized the app. It failed always.

By the way, I think you can make a same change and close this one.

[kerthcet]

Hi @congcongke I can help you with this if you want to contribute this PR. Maybe you can follow the doc: https://github.com/kubernetes/community/blob/master/CLA.md

[congcongke]

Hi @congcongke I can help you with this if you want to contribute this PR. Maybe you can follow the doc: https://github.com/kubernetes/community/blob/master/CLA.md

Yeah, thank you so much!

[kerthcet]

Could you add a test? #439 (comment)

[k8s-ci-robot]

New changes are detected. LGTM label has been removed.

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

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[congcongke]

Could you add a test? #439 (comment)

Sorry, forgot it.