What is VPA and how does it differ from HPA?

VPA (Vertical Pod Autoscaler) and HPA (Horizontal Pod Autoscaler) are mechanisms for automatic scaling in Kubernetes, but they operate differently:

• HPA (Horizontal Pod Autoscaler) scales the number of pod replicas based on load (CPU, memory, or custom metrics). For example, it increases the number of pods as load grows.

• VPA (Vertical Pod Autoscaler) adjusts the resources (CPU, memory) of existing pods, increasing or decreasing their allocation, but does not change the number of pods.

Example:

• HPA: from 2 to 5 pods as load increases.
• VPA: a pod's CPU allocation increases from 500m to 1 CPU.

Typically, HPA is used for scaling by the number of instances, while VPA is used for resource optimization within a pod.