Tutorial: Add an Azure Container Linux (ACL) node pool to your existing Azure Kubernetes Service (AKS) cluster

In AKS, nodes with the same configurations are grouped together into node pools. Each node pool contains the virtual machines (VMs) that run your applications. In the previous tutorial, you created an ACL cluster with a single node pool. To meet the varying compute, storage, or security requirements of your applications, you can add user node pools.

In this tutorial, part two of five, you learn how to:

The commands in this tutorial use the environment variables set in Tutorial 1: Create a cluster with ACL for AKS.

In later tutorials, you learn how to migrate nodes to ACL and enable telemetry to monitor your clusters.

Prerequisites

• In the previous tutorial, you created and deployed an ACL cluster. If you haven't completed these steps and want to follow along, see Tutorial 1: Create a cluster with ACL for AKS.
• Azure Container Linux requires Azure CLI version 2.86.0 or higher. Use the az version command to find the version. To upgrade to the latest version, use the az upgrade command.

Azure Container Linux (ACL) considerations and limitations

Before you begin, review the following considerations and limitations for ACL:

• ACL is generally available starting AKS v1.34.
• ACL requires Trusted Launch with Secure Boot and vTPM. Non-Trusted Launch variants aren't available.
• ACL on Arm64 requires Cobalt-based (v6) SKUs to enable Trusted Launch compatibility.
• NodeImage and None are the only supported operating system (OS) upgrade channels. Unmanaged and SecurityPatch are incompatible with ACL due to the immutable /usr directory.
• Artifact Streaming isn't supported.
• Pod Sandboxing isn't supported.
• Confidential Virtual Machines (CVMs) aren't supported.
• Generation 1 VMs aren't supported.
• FIPS-enabled nodes aren't supported.

Add an ACL node pool

Add an ACL node pool into your existing cluster using the az aks nodepool add command and specify --os-sku AzureContainerLinux. The following example creates a node pool named aclpool that adds three nodes to the cluster:

az aks nodepool add \
    --resource-group $RESOURCE_GROUP \
    --cluster-name $CLUSTER_NAME \
    --name aclpool \
    --node-count 3 \
    --os-sku AzureContainerLinux

Example output:

{
  "agentPoolType": "VirtualMachineScaleSets",
  "count": 3,
  "name": "aclpool",
  "osType": "Linux",
  "osSku": "AzureContainerLinux",
  "provisioningState": "Succeeded",
  "resourceGroup": "myACLResourceGroup",
  "type": "Microsoft.ContainerService/managedClusters/agentPools"
}

Check the node pool status

Check the status of your node pools using the az aks nodepool list command.

az aks nodepool list --resource-group $RESOURCE_GROUP_NAME --cluster-name $CLUSTER_NAME

Example output:

[
  {
    "agentPoolType": "VirtualMachineScaleSets",
    "count": 3,
    "name": "nodepool1",
    "nodeImageVersion": "AKSAzureContainerLinux-202606.01.0",
    "osSku": "AzureContainerLinux",
    "osType": "Linux",
    "provisioningState": "Succeeded",
    "resourceGroup": "myACLResourceGroup",
    "vmSize": "Standard_DS2_v2"
  },
  {
    "agentPoolType": "VirtualMachineScaleSets",
    "count": 3,
    "name": "aclpool",
    "nodeImageVersion": "AKSAzureContainerLinux-202606.01.0",
    "osSku": "AzureContainerLinux",
    "osType": "Linux",
    "provisioningState": "Succeeded",
    "resourceGroup": "myACLResourceGroup",
    "vmSize": "Standard_DS2_v2"
  }
]

Next step

In this tutorial, you added an ACL node pool to your existing cluster. In the next tutorial, you learn how to migrate existing nodes to ACL.