Azure Hands-On Lab - Patch and upgrade an AKS Cluster

📝Introduction

In this hands-on lab, we will apply patch updates and upgrade the AKS cluster to the latest supported Kubernetes version.

Diagram showing the lab process: applying patch upgrades to the out-of-support version before upgrading to the latest supported version.

Learning objectives

In this module, you'll learn how to:

Understand what Kubernetes versions AKS supports.
Upgrade your existing AKS cluster components to the latest supported Kubernetes version.
Upgrade your AKS clusters in production environments using a Blue/Green deployment.

📝Log in to the Azure Management Console

Using your credentials, make sure you're using the right Region. In my case, I am using the region southcentralus in my Cloud Playground Sandbox.

📌Note: You can also use the VSCode tool or from your local Terminal to connect to Azure CLI

More information on how to set it up is at the link.

📝Prerequisites:

Update to PowerShell 5.1, if needed.
Install .NET Framework 4.7.2 or later.
Visual Code
Web Browser (Chrome, Edge)
Azure CLI installed
Azure subscription
Docker installed

📝Setting an Azure Storage Account to Load Bash or PowerShell

Click the Cloud Shell icon (>_) at the top of the page.

Click PowerShell.

Click Show Advanced Settings. Use the combo box under Cloud Shell region to select the Region. Under Resource Group and Storage account(It's a globally unique name), enter a name for both. In the box under File Share, enter a name. Click ***Create storage (***if you don't have any yet).

📝Create an AKS cluster

In Azure Cloud Shell, create a resource group using the az group create command.
```
 az group create -l <location> -n <ResourceGroupName>
```
Check the current list of Kubernetes versions that AKS supports using the az aks get-versions command.
```
 az aks get-versions -l <location> -o table
```
Find the oldest supported Kubernetes version from the list and store it in a KV variable.
```
 KV=1.27.7
```
Get your resource group name and store it inside a variable named RG.
```
 az group list -o table 
 RG=<ResourceGroupName>
```

Create an AKS cluster using the az aks create command, but before storing the name of the cluster inside a variable named CLUSTERNAME.

 CLUSTERNAME=<AKSClusterName>
 az aks create -n $CLUSTERNAME -g $RG --kubernetes-version $KV --node-vm-size Standard_D2s_v3 --node-count 2 --generate-ssh-keys

📝Upgrade the AKS cluster

Check for available cluster upgrades using the az aks get-upgrades command.

az aks get-upgrades -n $CLUSTERNAME -g $RG -o table

You'll see the versions available for upgrades, which are the next three supported Kubernetes versions from the current AKS cluster version.

Try to immediately upgrade to the latest supported Kubernetes version using the az aks upgrade command and replace [latest-version] with the latest Kubernetes version from the previous step.
```
 az aks upgrade -n $CLUSTERNAME -g $RG -k [latest-version]
```
Confirm the upgrade using the az aks show command.
```
 az aks show -n $CLUSTERNAME -g $RG -o table
```
However, you might get an error message because you can't skip minor versions when upgrading your AKS cluster. This means depends on the running version you're using, for example, version 1.26.x maybe you can't immediately upgrade to version 1.28.x and above. In this case, you can skip patch version upgrades within a minor version and follow the next steps.

📝Apply patches updates

Apply patch updates to the AKS cluster using the az aks upgrade command and replace [next-patch-version] with the next patch version from the previous section.
```
 az aks upgrade -n $CLUSTERNAME -g $RG --no-wait -k [next-patch-version]
```
📌Note: It's possible to apply upgrades only to the control plane in the AKS cluster or only to the nodes in the AKS cluster by including the optional parameters --control-plane-only or --node-image-only when running the upgrade command. If the optional parameters aren't included, both the control plane and nodes in the AKS cluster are upgraded.
Confirm the patch upgrade using the az aks show command.
```
 az aks show -n $CLUSTERNAME -g $RG -o table
```

📝Upgrade to the next minor version

Upgrade the AKS cluster to the next supported Kubernetes minor version using the az aks upgrade command and replace [next-minor-version] with the next minor version from the previous section.
```
 az aks upgrade -n $CLUSTERNAME -g $RG --no-wait -k [next-minor-version]
```

Confirm the upgrade using the az aks show command.

 az aks show -n $CLUSTERNAME -g $RG -o table

Upgrade the cluster to the latest stable Kubernetes version AKS supports using the az aks upgrade command and replace [latest-stable-version] with the latest stable version from the previous section.
```
 az aks upgrade -n $CLUSTERNAME -g $RG --no-wait -k [latest-stable-version]
```

Confirm the upgrade using the az aks show command.

 az aks show -n $CLUSTERNAME -g $RG -o table

📌Note - At the end of each hands-on Lab, always clean up all resources previously created to avoid being charged.

Congratulations — you have completed this hands-on lab covering the basics of applying patch updates and upgrading the AKS cluster to the latest supported Kubernetes version.

Thank you for reading. I hope you understood and learned something helpful from my blog.

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