Ivan Glushkov, Staff Engineer at Postmates, describes the problem that led us to develop a configurable horizontal pod autoscaler (CHPA) for Kubernetes.

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