The document discusses the limitations and features of Kubernetes' Horizontal Pod Autoscaler (HPA) and introduces the Configurable Horizontal Pod Autoscaler (CHPA), which allows for more flexible scaling configurations per deployment. Key issues with HPA include hardcoded constants and limits on scaling speed, which CHPA seeks to address through customizable parameters. A Kubernetes Enhancement Proposal (KEP) is mentioned as a potential solution for enhancing scaling capabilities.

1. Configurable Horizontal
Pod Autoscaler
Ivan Glushkov, Staff Software Engineer

2. Kubernetes is not a rocket science
- Kubernetes building blocks: Pod, Deployment
- Horizontal Pod Autoscaler
- Simplicity, Idempotence,
Infrastructure-as-code, Development Velocity

3. HPA under the microscope
- Configuration:
- maxReplicas
- minReplicas
- metrics
- stabilizationWindow
- Hardcoded Constants:
- scaleUpLimitFactor = 2
- scaleUpLimitMinimum = 4

4. Use Case: business-critical web traffic

5. Use Case: data events

6. HPA Problems
- Cannot scale slower/faster
- Cannot delay the next scale
- All the configurations are hardcoded/cluster-wide

7. CHPA
- CRD + Controller
- Configuration (per deployment)
- ScaleUpLimitFactor
- ScaleUpLimitMinimum
- UpscaleForbiddenWindowSeconds
- DownscaleForbiddenWindowSeconds.

8. CHPA
- CRD + Controller
- Configuration
- ScaleUpLimitFactor
- ScaleUpLimitMinimum
- UpscaleForbiddenWindowSeconds
- DownscaleForbiddenWindowSeconds
How fast it can scale pods
How long to wait until next scale

9. CHPA: business-critical web traffic

10. CHPA: data events

11. General Solution
- Kubernetes Enhancement Proposal (KEP) “Configurable scale up/down
velocity for HPA”
- Kubernetes PR #74525
- Stay tuned

12. Questions