How does Kubernetes autoscaling work — HPA, VPA, and cluster autoscaler?

Question

"Our app gets 10x traffic during job fair season. We need auto-scaling."

Interview OS Community · Accepted Answer

## Autoscaling Types

**HPA** (Horizontal): Add more pods
```yaml
kind: HorizontalPodAutoscaler
spec:
  minReplicas: 2
  maxReplicas: 20
  metrics: [{ type: Resource, resource: { name: cpu, targetAverageUtilization: 70 } }]
```

**VPA** (Vertical): Increase pod resources (restarts pod)
**Cluster Autoscaler**: Add/remove nodes

| Type | Scales | Best For |
|------|--------|----------|
| HPA | Pod count | Web traffic |
| VPA | Pod resources | Memory-heavy workloads |
| Cluster | Node count | Overall capacity |

Strategy: HPA for web services + Cluster autoscaler to back it. VPA only for stable workloads.

Interview OS

How does Kubernetes autoscaling work — HPA, VPA, and cluster autoscaler?

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Autoscaling Types

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