What is HPA (Horizontal Pod Autoscaler)?
Kubernetes controller that automatically scales pod replicas based on observed metrics.
The Horizontal Pod Autoscaler (HPA) automatically scales the number of pod replicas in a Deployment or StatefulSet based on observed CPU utilization, memory, or custom metrics (from Prometheus Adapter or KEDA). It runs as a control loop that periodically checks metrics and adjusts replicas within configured min and max bounds. Cooldown periods (stabilizationWindowSeconds) prevent flapping. Custom metrics enable scaling on business metrics like queue length or HTTP requests per second.
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Related Terms
More Kubernetes Terms
Admission Controller
A Kubernetes plugin that intercepts API requests before objects are persisted.
Auto Scaling
Automatically adjusting the number of compute resources based on demand.
ClusterIP
The default Kubernetes Service type that exposes a service on an internal cluster IP.
ConfigMap
A Kubernetes object for storing non-sensitive configuration data as key-value pairs.
Controller Manager
Kubernetes control plane component running control loops to maintain desired state.
CoreDNS
The default DNS server in Kubernetes clusters for service discovery.
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