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KEP-4781 restarting kubelet does not change pod status #5493

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KEP-4781 restarting kubelet does not change pod status #5493

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@HirazawaUi HirazawaUi commented Aug 23, 2025 •
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  • One-line PR description: This KEP aims to ensure that restarting the kubelet for a short period does not affect the status of pods on the node.
  • Other comments:

@k8s-ci-robot k8s-ci-robot added the do-not-merge/work-in-progress Indicates that a PR should not merge because it is a work in progress. label Aug 23, 2025
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[APPROVALNOTIFIER] This PR is NOT APPROVED

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@k8s-ci-robot k8s-ci-robot added the cncf-cla: yes Indicates the PR's author has signed the CNCF CLA. label Aug 23, 2025
@k8s-ci-robot k8s-ci-robot added the kind/kep Categorizes KEP tracking issues and PRs modifying the KEP directory label Aug 23, 2025
@k8s-ci-robot k8s-ci-robot requested a review from mrunalp August 23, 2025 12:07
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@HirazawaUi HirazawaUi mentioned this pull request Aug 23, 2025
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@HirazawaUi HirazawaUi mentioned this pull request Aug 24, 2025
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@HirazawaUi HirazawaUi force-pushed the kep-4781 branch 2 times, most recently from eca940b to acbdb7e Compare August 25, 2025 15:34
@HirazawaUi HirazawaUi changed the title [WIP] KEP-4781 restarting kubelet does not change pod status KEP-4781 restarting kubelet does not change pod status Aug 25, 2025
@k8s-ci-robot k8s-ci-robot removed the do-not-merge/work-in-progress Indicates that a PR should not merge because it is a work in progress. label Aug 25, 2025
HirazawaUi
HirazawaUi commented Aug 25, 2025
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keps/sig-node/4781-kublet-restart-pod-status/README.md
By preserving the old state without immediate health checks, there is a delay in recognizing containers that have become unhealthy during or after kubelet's downtime. Services relying on Pod readiness for service discovery might continue directing traffic to Pods with containers that are no longer healthy but are still reported as Ready.
We plan to immediately trigger a probe after that to reduce the risk caused by such delays.

## Design Details
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@HirazawaUi HirazawaUi Aug 25, 2025 •
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I did not refer to the implementation approach of the previous KEP. After reviewing the POC PR related to that KEP, I found the implementation process somewhat cumbersome, and it also presented some potential edge case issues.

After tracing the pod status transition process, I adopted a new implementation method to achieve the goal: consistently relying on the detection results of the probeManager. This approach simplifies the implementation and helps us avoid certain edge cases. And in this section, the behavioral differences of kubelet under several scenarios are also analyzed. Could you please take a look?

My POC PR: kubernetes/kubernetes#133676

@SergeyKanzhelev @thockin

@HirazawaUi HirazawaUi mentioned this pull request Aug 26, 2025
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@toVersus toVersus mentioned this pull request Aug 29, 2025
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