In Azure K8s service, you can scale up the node pool but only we define the min and max nodes. When i check the node pool scale set scale settings, i found it set to manual. So i assume that the Node Pool auto scale does't rely on the belonging scale set, but i wonder, can we just rely on the scale set auto scale with the several metric roles instead of the very limited Node Pool scale settings ?
The AKS autoscaling works slightly different as the VMSS autoscaling.
From the official docs:
The cluster autoscaler watches for pods that can't be scheduled on nodes because of resource constraints. The cluster then automatically increases the number of nodes.
The AKS autoscaler is tightly coupled with the control plane and the kube-scheduler, so it takes resource requests and limits into account that is far the better scaling method as the VMSS autoscaler (for k8s workload) that is anyway not supported for AKS:
The cluster autoscaler is a Kubernetes component. Although the AKS cluster uses a virtual machine scale set for the nodes, don't manually enable or edit settings for scale set autoscale in the Azure portal or using the Azure CLI.