Use Generation 2 (Gen 2) virtual machines (VMs) on Azure Kubernetes Service (AKS)

2025-10-23

In this article, you learn how to use Generation 2 (Gen 2) virtual machines (VMs) on Azure Kubernetes Service (AKS), including how to check available Gen 2 VM sizes, create AKS node pools with Gen 2 VMs, migrate from Gen 1 to Gen 2 VMs on AKS, and verify the VM generation of your AKS nodes.

Before you begin

Review the Virtual machine (VM) sizes, generations, and features for Azure Kubernetes Service (AKS) article to understand VM generations and features supported on AKS.

Check available Gen 2 VM sizes

Check available Gen 2 VM sizes using the az vm list-skus command.

# Set environment variables
export LOCATION=<your-region>
export VM_SIZE=<vm-size-to-check>

# Check if the VM size is available in the specified location
az vm list-skus --location $LOCATION --size $VM_SIZE --output table

For a breakdown of what VM sizes support Gen 2, see Support for Gen 2 VMs on Azure.

By default, Linux uses the Gen 2 node image unless the VM size doesn't support Gen 2.

Create a Linux node pool with a Gen 2 VM using the default node pool creation process.

By default, Windows Server 2022 uses the Gen 1 node image. If you want to use a Gen 2 node image, create a Windows node pool using the az aks nodepool add command with the --aks-custom-headers UseWindowsGen2VM=true custom header --aks-custom-headers UseWindowsGen2VM=true:

# Set environment variables
export RESOURCE_GROUP=<resource-group-name>
export CLUSTER_NAME=<cluster-name>
export NODE_POOL_NAME=<node-pool-name>
export VM_SIZE=<supported-generation-2-vm-size>

# Create a Windows node pool with a Gen 2 VM
az aks nodepool add --resource-group $RESOURCE_GROUP --cluster-name $CLUSTER_NAME --name $NODE_POOL_NAME --node-vm-size $VM_SIZE --os-type Windows --os-sku Windows2022 --aks-custom-headers UseWindowsGen2VM=true

Windows Server 2025+ uses the Gen 2 node image by default, so you don't need to specify the custom header.

Migrate an existing node pool to Gen 2

Linux node pool
Windows node pool

If you're using a VM size that only supports Gen 1, you can update your node pool to a VM size that supports Gen 2 using the az aks nodepool update command. This update changes your node image from Gen 1 to Gen 2.

# Set environment variables
export RESOURCE_GROUP=<resource-group-name>
export CLUSTER_NAME=<cluster-name>
export NODE_POOL_NAME=<node-pool-name>
export VM_SIZE=<supported-generation-2-vm-size>

# Update a Linux node pool to use a Gen 2 VM
az aks nodepool update --resource-group $RESOURCE_GROUP --cluster-name $CLUSTER_NAME --name $NODE_POOL_NAME --node-vm-size $VM_SIZE --os-type Linux

If you're Windows Server 2022 with the Gen 1 image, you can update your node pool to use Gen 2 by selecting a VM size that supports Gen 2 using the az aks nodepool update command with the --aks-custom-headers UseWindowsGen2VM=true custom header:

# Set environment variables
export RESOURCE_GROUP=<resource-group-name>
export CLUSTER_NAME=<cluster-name>
export NODE_POOL_NAME=<node-pool-name>
export VM_SIZE=<supported-generation-2-vm-size>

# Update a Windows node pool to use a Gen 2 VM
az aks nodepool update --resource-group $RESOURCE_GROUP --cluster-name $CLUSTER_NAME --name $NODE_POOL_NAME --node-vm-size $VM_SIZE --os-type Windows --os-sku Windows2022 --aks-custom-headers UseWindowsGen2VM=true

Check if you're using a Gen 2 node image

Verify a successful node pool creation using the az aks nodepool show command and check that the nodeImageVersion contains gen2 in the output.

# Set environment variables
export RESOURCE_GROUP=<resource-group-name>
export CLUSTER_NAME=<cluster-name>
export NODE_POOL_NAME=<node-pool-name>

# Show node pool details
az aks nodepool show --resource-group $RESOURCE_GROUP --cluster-name $CLUSTER_NAME --name $NODE_POOL_NAME --output table

Next steps

To learn more about Gen 2 VMs, see Support for Generation 2 VMs on Azure
To learn more about supported Gen 2 node images, see Node images

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