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Support for topology spread constraints with cluster autoscaler
When a deployment is applied using topology spread constraints with a maxSkew of 1 and topology key "topology.kubernetes.io/zone" the cluster autoscaler scales up 1 zone with too many nodes and after the scale-down-unneeded-time has passed they will be removed again. There is a nodepool for each zone (3) and balance-similar-node-groups is set to true.
I would expect nodes to be added to each zone with the similar number of nodes and not unneeded nodes extra being added which are removed again the after scale-down-unneeded-time timeout.
The issue can be reproduced by applying a deployment with resource requests sized about half the size of the nodes, about 30 pods and with topology spread constraints configured:
topologySpreadConstraints: - maxSkew: 1 topologyKey: topology.kubernetes.io/zone whenUnsatisfiable: DoNotSchedule
Cluster setup with autoscaled nodepools per zone and with balance-similar-node-groups set to true..
MS support ticket 2112070050001650 was opened for this issue. Was told there is no special integration between pod topology spreading and CA as in this this behavior is expected. Advised to open issue and request for integration of topology spread constraints.
Kubernetes 1.21.9 1 system nodepool (Standard_D16as_v4) with 3 nodes (no autoscaling) 3 user nodepools (1 per zone, Standard_D16as_v4) and cluster autoscaling (3 - 30)
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Hi my customer has the same issue using PodAntiaffinity and the CA never triggering when pods cannot be scheduled.
To be sure, is it linked to this issue ?
