gce: register all zonal MIGs of a multi-zone instance group with cluster-autoscaler - #18543
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kubernetes-prow[bot] merged 3 commits intoJul 7, 2026
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The nodes instance group in this scenario spans two zones, so kOps creates two zonal InstanceGroupManagers, but only the first zone's MIG is registered with cluster-autoscaler. The expected output captures this current behavior.
…ter-autoscaler For a GCE instance group spanning multiple zones, kOps creates one zonal InstanceGroupManager per zone, but only registered the first zone's MIG with cluster-autoscaler, carrying the full min/max of the instance group. The MIGs in the remaining zones were invisible to the autoscaler and were never scaled, so scale-ups could get stuck in a single zone (for example when that zone has no spot capacity). Register each zonal MIG as its own cluster-autoscaler node group, splitting the instance group's min/max sizes across zones with the same algorithm used for the MIG target sizes. Single-zone instance groups render exactly as before.
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…-upstream-release-1.36 Automated cherry pick of #18543: gce: register all zonal MIGs of a multi-zone instance group with cluster-autoscaler
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For a GCE instance group spanning multiple zones, kOps creates one zonal InstanceGroupManager per zone, but only registered the first zone's MIG with cluster-autoscaler, carrying the full min/max of the instance group. The MIGs in the remaining zones were invisible to the autoscaler and were never scaled, so scale-ups could get stuck in a single zone (for example when that zone has no spot capacity).
Register each zonal MIG as its own cluster-autoscaler node group, splitting the instance group's min/max sizes across zones with the same algorithm used for the MIG target sizes. Single-zone instance groups render exactly as before.
/cc @rifelpet @ameukam
CC @0xhaven