Configure Cluster Autoscaler for your Kubernetes Version

This guide will walk you through configuring the Cluster Autoscaler after you have upgraded your control plane from Kubernetes 1.19 to 1.20 or from 1.20 to 1.21.

Note

This guide assumes that you have already deployed the Cluster Autoscaler on your cluster. If this does not hold, please proceed to the corresponding guide for deploying the Cluster Autoscaler on your cluster.

What You’ll Need

Check Your Environment

  1. Get the version of the Kubernetes control plane. Choose one of the following options, based on the upgrade you’ve made:

    Kubernetes 1.20 to 1.21

    Kubernetes 1.19 to 1.20

    root@rok-tools:~# kubectl version -ojson | jq -r '.serverVersion.gitVersion' v1.21.5-eks-bc4871b

    This guide presumes that you have upgraded your control plane to Kubernetes 1.21. The output of the above command must start with v1.21. If it does not, your control plane does not have the expected Kubernetes version. Please upgrade your control plane before proceeding.

    root@rok-tools:~# kubectl version -ojson | jq -r '.serverVersion.gitVersion' v1.20.11-eks-f17b81

    This guide presumes that you have upgraded your control plane to Kubernetes 1.20. The output of the above command must start with v1.20. If it does not, your control plane does not have the expected Kubernetes version. Please upgrade your control plane before proceeding.

Procedure

  1. Go to your GitOps repository, inside your rok-tools management environment:

    root@rok-tools:~# cd ~/ops/deployments

  2. Edit the Cluster Autoscaler overlay that corresponds to your Kubernetes version. Choose one of the following options, based on the upgrade you’ve made:

    Kubernetes 1.20 to 1.21

    Kubernetes 1.19 to 1.20

    1. Edit rok/cluster-autoscaler/overlays/deploy/kustomization.yaml and use k8s-1.21 instead of k8s-1.20 as the base overlay:

      resources: #- ../../base #- ../k8s-1.19 #- ../k8s-1.20 - ../k8s-1.21

    1. Edit rok/cluster-autoscaler/overlays/deploy/kustomization.yaml and use k8s-1.20 instead of k8s-1.19 as the base overlay:

      resources: #- ../../base #- ../k8s-1.19 - ../k8s-1.20 #- ../k8s-1.21

    Air Gapped

    Patch the kustomization to use the mirrored images:

    root@rok-tools:~/ops/deployments# rok-image-patch \ > --kustomizations rok/cluster-autoscaler/overlays/deploy

    Follow the on-screen instructions and provide any necessary input.

  3. Commit your changes. Choose one of the following options, based on the upgrade you’ve made:

    Kubernetes 1.20 to 1.21

    Kubernetes 1.19 to 1.20

    root@rok-tools:~/ops/deployments# git commit -am "Configure Cluster Autoscaler for Kubernetes 1.21"
    root@rok-tools:~/ops/deployments# git commit -am "Configure Cluster Autoscaler for Kubernetes 1.20"

  4. Mark your progress:

    root@rok-tools:~/ops/deployments# export DATE=$(date -u "+%Y-%m-%dT%H.%M.%SZ")
    root@rok-tools:~/ops/deployments# git tag \ > -a deploy/${DATE?}/release-1.5/ops-eks-upgrade-autoscaler \ > -m "Configure Cluster Autoscaler for your Kubernetes Version"

  5. Apply the kustomization:

    root@rok-tools:~/ops/deployments# rok-deploy --apply rok/cluster-autoscaler/overlays/deploy

Verify

  1. Verify that the Cluster Autoscaler is up and running. Verify that field READY is 1/1:

    root@rok-tools:~# kubectl get -n kube-system deploy/cluster-autoscaler NAME READY UP-TO-DATE AVAILABLE AGE cluster-autoscaler 1/1 1 1 1m

  2. Get the image of the Cluster Autoscaler and ensure that the image tag matches the Kubernetes version 1.20, that is, it starts with 1.20:

    root@rok-tools:~# kubectl -n kube-system get deploy cluster-autoscaler \ > -o jsonpath='{.spec.template.spec.containers[].image}{"\n"}' gcr.io/arrikto/cluster-autoscaler-amd64:1.20.2-19-g72e45e047

Summary

You have successfully configured Cluster Autoscaler for Kubernetes 1.21.

What’s Next

Check out the rest of the EKS maintenance operations that you can perform on your cluster.

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