In this Chapter, we will show patterns for scaling your worker nodes and applications deployments automatically. Automatic scaling in K8s comes in two forms:
Horizontal Pod Autoscaler (HPA) scales the pods in a deployment or replica set. It is implemented as a K8s API resource and a controller. The controller manager queries the resource utilization against the metrics specified in each HorizontalPodAutoscaler definition. It obtains the metrics from either the resource metrics API (for per-pod resource metrics), or the custom metrics API (for all other metrics).
Cluster Autoscaler (CA) a component that automatically adjusts the size of a Kubernetes Cluster so that all pods have a place to run and there are no unneeded nodes.