AKS upgrade 1.19.11 to latest one

Question

Hi there!

We got notification from Azure that our cluster is too old and we should update it to latest version. Unfortunately, when we started working on it we found that next 1.20, 1.21 AKS versions are not supported anymore and we are not able to perform upgrade sequentially, so the only option to upgrade from 1.19.11 -> 1.22. Docs say there is no guarantee that everything would be up and running after this upgrade and it may lead to downtime https://learn.microsoft.com/en-us/azure/aks/tutorial-kubernetes-upgrade-cluster?tabs=azure-cli#upgrade-a-cluster

So my question is should we try to perform such an upgrade or it will lead to disaster? Maybe it is better to recreate AKS in such a case.

Thanks!

Answer 1

Hello @devops ,
Yes, it is recommended to re-create your cluster as mentioned above by Andriy.

When performing an upgrade from an unsupported version that skips two or more minor versions, the upgrade is performed without any guarantee of functionality and is excluded from the service-level agreements and limited warranty. If your version is significantly out of date, it's recommended to re-create the cluster.

I would recommend you to set-up auto upgrades for your cluster as it is a set once and forget mechanism that yields tangible time and operational cost benefits. By enabling auto-upgrade, you can ensure your clusters are up to date and don't miss the latest AKS features or patches from AKS and upstream Kubernetes.

Automatically completed upgrades are functionally the same as manual upgrades. The timing of upgrades is determined by the selected channel. When making changes to auto-upgrade, allow 24 hours for the changes to take effect.

There are 4 types of channels available:

You can learn more about it here : https://learn.microsoft.com/en-us/azure/aks/auto-upgrade-cluster

Hope this helps. If you have further queries, feel free to reach back.

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Answer 2

Hello @devops

There reason, why Azure AKS supports only two last version is Kubernetes Version Skew Policy

Worker nodes are not allowed more than two minor version behind the master node.

To avoid disruption of your cluster I would recommend you to create new AKS cluster and migrate all workloads from old cluster to new cluster