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[CCM - service controller] Remove schedulability predicate for LB set #111691

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alexanderConstantinescu
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@alexanderConstantinescu alexanderConstantinescu commented Aug 4, 2022

What type of PR is this?

/kind regression

What this PR does / why we need it:

PR #109706 re-added the schedulability predicate to the node sync path, causing nodes to be removed from the LB set if any node goes unschedulable. This doesn't seem to be correct however, specifically: it seems it was removed with #90823 which listed a production outage caused by the fact that we were syncing LBs as a cause by the schedulability constraint changing on a set of nodes. #90823 mentioned:

This caused a production outage when nodes in an autoscaling group were marked unschedulable so the autoscaler would gracefully terminate them - instead the ingress controllers on those nodes were immediately removed from the LB pool and no new ingress requests could be accepted.

Which will most certainly be the case again after #109706 since any node going unschedulable will be removed from the LB set.

The PR that added the schedulability predicate to the "update predicates" was: #90769, but it didn't list any good reasons for doing so...given this new information it seems the reverse holds true, we should not be removing nodes from the LB set because of this attribute, and we should most likely not even care about this attribute when syncing updates to nodes.

This PR thus removes that predicate altogether.

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

I am unsure of if we want this PR, or just revert #109706 at this point. But posting this here for efficiency's sake.

Does this PR introduce a user-facing change?

Remove the recently re-introduced schedulability predicate (by PR: https://github.com/kubernetes/kubernetes/pull/109706) as to not have unschedulable nodes removed from load balancers back-end pools.   

Additional documentation e.g., KEPs (Kubernetes Enhancement Proposals), usage docs, etc.:


/assign @thockin
/sig network
/sig cloud-provider

@k8s-ci-robot k8s-ci-robot added release-note Denotes a PR that will be considered when it comes time to generate release notes. kind/bug Categorizes issue or PR as related to a bug. size/XL Denotes a PR that changes 500-999 lines, ignoring generated files. sig/network Categorizes an issue or PR as relevant to SIG Network. sig/cloud-provider Categorizes an issue or PR as relevant to SIG Cloud Provider. cncf-cla: yes Indicates the PR's author has signed the CNCF CLA. needs-triage Indicates an issue or PR lacks a `triage/foo` label and requires one. labels Aug 4, 2022
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k8s-ci-robot commented Aug 4, 2022

@alexanderConstantinescu: This issue is currently awaiting triage.

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@k8s-ci-robot k8s-ci-robot added needs-priority Indicates a PR lacks a `priority/foo` label and requires one. needs-ok-to-test Indicates a PR that requires an org member to verify it is safe to test. labels Aug 4, 2022
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k8s-ci-robot commented Aug 4, 2022

Hi @alexanderConstantinescu. Thanks for your PR.

I'm waiting for a kubernetes 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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alexanderConstantinescu commented Aug 4, 2022

/remove-kind bug
/kind regression

@k8s-ci-robot k8s-ci-robot added kind/regression Categorizes issue or PR as related to a regression from a prior release. and removed kind/bug Categorizes issue or PR as related to a bug. labels Aug 4, 2022
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aojea commented Aug 4, 2022

/ok-to-test

@k8s-ci-robot k8s-ci-robot added ok-to-test Indicates a non-member PR verified by an org member that is safe to test. and removed needs-ok-to-test Indicates a PR that requires an org member to verify it is safe to test. labels Aug 4, 2022
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aojea commented Aug 4, 2022

/kind bug

@k8s-ci-robot k8s-ci-robot added the kind/bug Categorizes issue or PR as related to a bug. label Aug 4, 2022
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@thockin thockin left a comment

Thanks!

/lgtm
/approve
/ok-to-test

@thockin thockin added this to the v1.25 milestone Aug 4, 2022
@k8s-ci-robot k8s-ci-robot added the lgtm Indicates that a PR is ready to be merged. label Aug 4, 2022
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k8s-ci-robot commented Aug 4, 2022

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: alexanderConstantinescu, thockin

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@k8s-ci-robot k8s-ci-robot added the approved Indicates a PR has been approved by an approver from all required OWNERS files. label Aug 4, 2022
@k8s-ci-robot k8s-ci-robot merged commit d0c92ae into kubernetes:master Aug 4, 2022
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