Kubernetes unknown field "behavior"

Question

I'm creating a HorizontalPodAutoscaler in Kubernetes and I need to configure the downscale stabilization window to be smaller than the default. The code used and error are below:

apiVersion: autoscaling/v2beta2
kind: HorizontalPodAutoscaler
metadata:
    name: busy-autoscaler
spec:
    behavior:
        scaleDown:
            stabilizationWindowSeconds: 10
    scaleTargetRef:
        apiVersion: apps/v1
        kind: Deployment
        name: busy-worker
    minReplicas: 1
    maxReplicas: 2
    metrics:
        - type: Resource
          resource:
              name: cpu
              target:
                  type: Utilization
                  averageUtilization: 50

$ kubectl create -f some-autoscale.yaml
error validating "some-autoscale.yaml": error validating data: ValidationError(HorizontalPodAutoscaler.spec): unknown field "behavior" in io.k8s.api.autoscaling.v2beta2.HorizontalPodAutoscalerSpec

My understanding is that the behavior field should be supported from Kubernetes 1.17 as stated in the docs. Running kubectl version gives the following output:

Client Version: version.Info{Major:"1", Minor:"17", GitVersion:"v1.17.1", GitCommit:"d224476cd0730baca2b6e357d144171ed74192d6", GitTreeState:"clean", BuildDate:"2020-01-14T21:04:32Z", GoVersion:"go1.13.5", Compiler:"gc", Platform:"linux/amd64"}
Server Version: version.Info{Major:"1", Minor:"17", GitVersion:"v1.17.0", GitCommit:"70132b0f130acc0bed193d9ba59dd186f0e634cf", GitTreeState:"clean", BuildDate:"2019-12-07T21:12:17Z", GoVersion:"go1.13.4", Compiler:"gc", Platform:"linux/amd64"}

The API reference doesn't have the behavior field for v2beta2 which makes this more confusing.

I'm running Minikube 1.6.2 locally. What am I doing wrong?

Answer 1

So it looks like this was a case of incorrect documentation that was corrected shortly after I asked my question. PR #18157 on kubernetes/website adds the following text to the page on the Horizontal Pod Autoscaler.

Starting from v1.17 the downscale stabilization window can be set on a per-HPA basis by setting the behavior.scaleDown.stabilizationWindowSeconds field in the v2beta2 API. See Support for configurable scaling behavior.

PR #18965 reverts the previous pull request since the behavior object is functionality targeted in 1.18, not 1.17.

For now, the solution is to use the --horizontal-pod-autoscaler-downscale-stabilization flag on the controller manager as mentioned in @ShantyMan's answer above which will set the value for every HPA.

Answer 2

Client Version: v1.20.2 Server Version: v1.18.9-eks-d1db3c

Make sure kubectl api-versions and your cluster supports autoscaling/v2beta2

apiVersion: autoscaling/v2beta2
kind: HorizontalPodAutoscaler
metadata:
  name: {{ template "ks.fullname" . }}-keycloak
spec:
  scaleTargetRef:
    apiVersion: apps/v1
    kind: Deployment
    name: {{ template "ks.fullname" . }}-keycloak
  minReplicas: {{ .Values.keycloak.hpa.minpods }}
  maxReplicas: {{ .Values.keycloak.hpa.maxpods }}
  metrics:
  - type: Resource
    resource:
      name: memory
      target:
        type: Utilization
        averageUtilization: {{ .Values.keycloak.hpa.memory.averageUtilization }}
  - type: Resource
    resource:
      name: cpu
      target:
        type: Utilization
        averageUtilization: {{ .Values.keycloak.hpa.cpu.averageUtilization }}
  behavior:
    scaleDown:
      stabilizationWindowSeconds: {{ .Values.keycloak.hpa.stabilizationWindowSeconds }}
      policies:
        - type: Pods
          value: 1
          periodSeconds: {{ .Values.keycloak.hpa.periodSeconds }}