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QuickStartGuide.md

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Quick Start Guide

Create a deployment

Let's start a deployment chpa-example, that will imitate your real application:

kubectl run chpa-example --image=k8s.gcr.io/hpa-example --requests=cpu=200m --expose --port=80

Create a CHPA

Then let's create a CHPA manifest that'll specify forbidden windows, min and max replicas, and our deployment name.

cat > chpa.yaml << EOF
apiVersion: autoscalers.postmates.com/v1beta1
kind: CHPA
metadata:
  labels:
    controller-tools.k8s.io: "1.0"
  name: chpa-example
spec:
  downscaleForbiddenWindowSeconds: 15
  upscaleForbiddenWindowSeconds: 15
  scaleTargetRef:
    kind: Deployment
    name: chpa-example
  minReplicas: 1
  maxReplicas: 10
  metrics:
  - type: Resource
    resource:
      name: cpu
      targetAverageUtilization: 50
EOF

Let's apply the manifest:

kubectl apply -f chpa.yaml

NB: the deployment and the chpa for that deployment should be started in the same namespace!

Add some load

Now, let's add some load for our deployment to check how it will scale:

$ kubectl run -i --tty my-load-generator --image=busybox /bin/sh
/ #     # we are in the k8s container, let's create some load
/ # while true; do wget -q -O- chpa-example; done;
OK!OK!OK!OK!OK!OK!OK!...

Check how deployment scales

Run in a separate shell:

❯ kubectl get deploy chpa-example -w
NAME            DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE
chpa-example   1         1         1            1           1h55m
chpa-example   4     1     1     1     1h55m
chpa-example   4     1     1     1     1h55m
chpa-example   4     1     1     1     1h55m
chpa-example   4     4     4     1     1h55m
chpa-example   4     4     4     2     1h56m
chpa-example   4     4     4     3     1h56m
chpa-example   4     4     4     4     1h56m
chpa-example   7     4     4     4     1h57m
chpa-example   7     4     4     4     1h57m
chpa-example   7     4     4     4     1h57m
chpa-example   7     7     7     4     1h57m
chpa-example   7     7     7     5     1h57m
chpa-example   7     7     7     6     1h58m
chpa-example   7     7     7     7     1h58m
chpa-example   1     7     7     7     1h59m
chpa-example   1     7     7     7     1h59m
chpa-example   1     1     1     1     1h59m

As you can see, the deployment scaled up from 1 to 7 instances in 2 minutes. Then it scaled down to 1 replicas again.

That would be impossible with the vanilla HPA, where ScaleUpForbiddenWindow is 3min and ScaleDownForbiddenWindow is 5min.

Delete the CHPA

If you decided to stop using the CHPA, you should carefully remove the CHPA without removing the deployment itself. To do it just add --cascade=false parameter to the kubect delete command:

kubectl delete chpas.autoscalers.postmates.com chpa-example --cascade=false

The thing is that CHPA is registered as an Owner for the deployment. When we delete the owner of the deployment, the deployment is garbage collected.

Clean everything else

We don't want to leave the garbage behind

kubectl delete deploy/my-load-generator deploy/chpa-example