What Is a Cluster Autoscaler Controller?
A cluster autoscaler watches for pods that cannot schedule due to insufficient resources and grows the node pool to make room. When nodes sit underutilized and their pods can move elsewhere, it drains and removes them to cut spend. It works in tandem with pod autoscalers, which change replica counts rather than node counts.
Why it matters
Pod-level autoscaling is useless if there are no nodes to place the new pods on, which is the gap the cluster autoscaler fills. Reclaiming idle nodes keeps infrastructure cost aligned with real demand.
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