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[WIP] Add podAntiAffinity to node-healthceck-controller-manager Deployment to improve HA #377

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[WIP] Add podAntiAffinity to node-healthceck-controller-manager Deployment to improve HA #377

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kattz-kawa
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Why we need this PR

In the current deployment configuration, multiple replicas of the node-healthcheck-controller-manager can be scheduled on the same node. This creates a single point of failure. This setup does not fully utilize the benefits of having multiple replicas. With better placement, we can use the replicas more effectively.

Changes made

Changes made

  • Added a new patch file podantiaffinity_patch.yaml under config/patches/affinity/
    • Updated "config/patches/affinity/kustomization.yaml" to include the new patch
    • The patch is scoped to the node-healthcheck-controller-manager Deployment only by specifying name: controller-manager in the patch target
  • Defines podAntiAffinity rules to prevent scheduling both replicas on the same node
    • Matches pods with:
      • app.kubernetes.io/component: controller-manager
      • app.kubernetes.io/name: node-healthcheck-operator
      • Uses topologyKey: kubernetes.io/hostname

Which issue(s) this PR fixes

Test plan

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openshift-ci bot commented Jul 31, 2025

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: kattz-kawa
Once this PR has been reviewed and has the lgtm label, please assign slintes for approval. For more information see the Code Review Process.

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openshift-ci bot commented Jul 31, 2025

Hi @kattz-kawa. Thanks for your PR.

I'm waiting for a medik8s 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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slintes commented Aug 5, 2025

we have 3 PRs now with the same topic, let's finish discussion on one of the others first, before going on with this one...

medik8s/fence-agents-remediation#178
medik8s/self-node-remediation#180

@kattz-kawa kattz-kawa mentioned this pull request Aug 14, 2025
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@kattz-kawa
Add podAntiAffinity to node-healthceck-controller-manager deployment …
083f3bf 
…to improve HA

Use preferred podAntiAffinity for node-healthcheck-controller-manager to improve HA by avoiding co-scheduling of replicas on the same node.

Signed-off-by: Katsuya Kawakami <[email protected]>
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@slintes
I've updated this PRs to use preferredDuringScheduling as discussed. (medik8s/fence-agents-remediation#178)

Please let me know if you have any further feedback or if anything needs adjustment.

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