Upgrading an on-premises Kubernetes cluster can be very cumbersome and time-consuming task. It’s not just a single upgrade command that you can execute and everything happens magically behind the scenes. A single command for upgrading an entire Kubernetes cluster would be awesome 💚 and that’s exactly what’s provided by the AKS team. A single command to upgrade all your masters and nodes.

My fellow MVP Tobias Zimmergren wrote a great post on how to upgrade AKS clusters a couple of weeks ago. But technology and tools are changing quickly these days.

When you follow the instructions described by Tobias, you’ll result in some ugly warnings. This is because the az aks get-versions command is outdated and will be deprecated in the future.

That said, I just want to dump the commands I use to upgrade my Kubernetes cluster on AKS.

Examine your cluster

You can get the current Kubernetes version and all available upgrade in a single command.

az aks get-upgrades 
  --resource-group your-resgroup-name
  --name your-aks-name
  --query "{ current: controlPlaneProfile.kubernetesVersion,upgrades: controlPlaneProfile.upgrades }"

The command is using the JMESPath query language to extract the essential properties from the response. You should now see a JSON object similar to this one:

{
    "current": "1.7.9",
    "upgrades": [
        "1.7.12",
        "1.8.1",
        "1.8.2",
        "1.8.6",
        "1.8.7"
    ]
}

Upgrade your cluster

Starting the upgrade is as simple querying for new upgrades, it’s just the following command

az aks upgrade 
  --resource-group your-resgroup-name
  --name your-aks-name
  --kubernetes-version 1.8.7

After confirming the operation, you can grep another cup of ☕️ and wait for the upgrade process to finish.

Once finished, you can rerun the az aks get-upgrades command and verify the version of your cluster. It will now be 1.8.7. and you’ll see a couple of new upgrades. I’m not 100% sure why a two-stage upgrade is required in order to move from 1.7.9 to 1.9.2 but if you really want to use latest and greatest supported by AKS, repeat the az aks upgrade command and move on to 1.9.2. 🤘