Kubernetes Horizontal Pod Autoscaler
The Horizontal Pod Autoscaler (HPA) is a Kubernetes resource that automatically scales the number of pods in a deployment, replica set, or stateful set based on observed CPU utilization or custom metrics. It works by periodically checking metrics from the Kubernetes Metrics API or a custom metrics API, then adjusting the replica count to maintain a target metric value. This enables applications to handle varying loads efficiently by scaling out when demand increases and scaling in when demand decreases.
Developers should use HPA when running applications on Kubernetes that experience variable traffic or workload patterns, such as web services, APIs, or batch processing jobs, to ensure optimal resource utilization and cost-efficiency. It is particularly useful in cloud environments where scaling can reduce operational costs by avoiding over-provisioning, and it helps maintain performance and availability during traffic spikes without manual intervention.