coredns: Honor node taints in hostname topologySpreadConstraint - #18535
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The hostname topologySpreadConstraint uses whenUnsatisfiable: DoNotSchedule, but CoreDNS autoscales via the cluster-proportional-autoscaler. On clusters with a single schedulable worker (e.g. one control-plane + one worker), the tainted control-plane node was counted as an empty topology domain, so the second CoreDNS replica could never satisfy maxSkew and stayed Pending. Setting nodeTaintsPolicy: Honor excludes nodes with untolerated taints (control-plane, cordoned/draining) from the skew calculation, keeping the hard spread across workers while allowing the replicas to co-locate when there is only one eligible node.
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…-upstream-release-1.36 Automated cherry pick of #18535: coredns: Honor node taints in hostname topologySpreadConstraint
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The hostname topologySpreadConstraint uses whenUnsatisfiable: DoNotSchedule, but CoreDNS autoscales via the cluster-proportional-autoscaler. On clusters with a single schedulable worker (e.g. one control-plane + one worker), the tainted control-plane node was counted as an empty topology domain, so the second CoreDNS replica could never satisfy maxSkew and stayed Pending.
Setting nodeTaintsPolicy: Honor excludes nodes with untolerated taints (control-plane, cordoned/draining) from the skew calculation, keeping the hard spread across workers while allowing the replicas to co-locate when there is only one eligible node.
Fixes #18453
/cc @rifelpet @ameukam