CODEWITHSUNDEEP
kuberneteshpakubernetes-hpa
Nitesh Nayak
Nitesh Nayak

Reputation: 21

How can I control scale down of pods based on AZ zones in kubernetes HPA (Horizontal Pod Autoscaler)?

I am trying to load balance EKS cluster pods according to Availability Zones. I have configured "topologySpreadConstraints" in deployment for pod scale-up which works fine

spec:
  topologySpreadConstraints:
  - maxSkew: 1
    topologyKey: topology.kubernetes.io/zone
    whenUnsatisfiable: ScheduleAnyway

But during scale-down, it removes pods randomly and eventually keeps the cluster unbalanced across AZs.

Example: I have a service "test" running with 6 pods in 3 AZs (AZ-a, AZ-b, AZ-c) According to the above configuration when I scale up to 9 following happens as expected:

Initial -> AZ-a=2, AZ-b=2, AZ-c=2 After scale up -> AZ-a=3, AZ-b=3, AZ-c=3

But when it scales down to 6 pods due to HPA configuration it goes into an unbalanced state After scale down -> AZ-a=3, AZ-b=2, AZ-c=1

HPA configuration is as below

spec:
  maxReplicas: 12
  minReplicas: 6
  scaleTargetRef:
    apiVersion: apps/v1
    kind: Deployment
    name: test
  targetCPUUtilizationPercentage: 50

How can we mention either in HPA or deployment to scale down according to AZ again so that the scaled-down version is balanced as well?

Upvotes: 2

Views: 455

Answers (0)

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