Create and configure an Azure Kubernetes Services (AKS) cluster to use virtual nodes using the Azure CLI
This article shows you how to use the Azure CLI to create and configure the virtual network resources and AKS cluster, then enable virtual nodes.
Before you begin
Virtual nodes enable network communication between pods that run in Azure Container Instances (ACI) and the AKS cluster. To provide this communication, a virtual network subnet is created and delegated permissions are assigned. Virtual nodes only work with AKS clusters created using advanced networking (Azure CNI). By default, AKS clusters are created with basic networking (kubenet). This article shows you how to create a virtual network and subnets, then deploy an AKS cluster that uses advanced networking.
Before using virtual nodes with AKS, review both the limitations of AKS virtual nodes and the virtual networking limitations of ACI. These limitations affect the location, networking configuration, and other configuration details of both your AKS cluster and the virtual nodes.
If you have not previously used ACI, register the service provider with your subscription. You can check the status of the ACI provider registration using the az provider list command, as shown in the following example:
az provider list --query "[?contains(namespace,'Microsoft.ContainerInstance')]" -o table
The Microsoft.ContainerInstance provider should report as Registered, as shown in the following example output:
Namespace RegistrationState RegistrationPolicy --------------------------- ------------------- -------------------- Microsoft.ContainerInstance Registered RegistrationRequired
If the provider shows as NotRegistered, register the provider using the az provider register as shown in the following example:
az provider register --namespace Microsoft.ContainerInstance
Launch Azure Cloud Shell
The Azure Cloud Shell is a free interactive shell that you can use to run the steps in this article. It has common Azure tools preinstalled and configured to use with your account.
To open the Cloud Shell, select Try it from the upper right corner of a code block. You can also launch Cloud Shell in a separate browser tab by going to https://shell.azure.com/bash. Select Copy to copy the blocks of code, paste it into the Cloud Shell, and press enter to run it.
If you prefer to install and use the CLI locally, this article requires Azure CLI version 2.0.49 or later. Run
az --version to find the version. If you need to install or upgrade, see Install Azure CLI.
Create a resource group
An Azure resource group is a logical group in which Azure resources are deployed and managed. Create a resource group with the az group create command. The following example creates a resource group named myResourceGroup in the westus location.
az group create --name myResourceGroup --location westus
Create a virtual network
Virtual node requires a custom virtual network and associated subnet. It can't be associated with the same virtual network the AKS cluster is deployed to.
Create a virtual network using the az network vnet create command. The following example creates a virtual network name myVnet with an address prefix of 10.0.0.0/8, and a subnet named myAKSSubnet. The address prefix of this subnet defaults to 10.240.0.0/16:
az network vnet create \ --resource-group myResourceGroup \ --name myVnet \ --address-prefixes 10.0.0.0/8 \ --subnet-name myAKSSubnet \ --subnet-prefix 10.240.0.0/16
Now create an additional subnet for virtual nodes using the az network vnet subnet create command. The following example creates a subnet named myVirtualNodeSubnet with the address prefix of 10.241.0.0/16.
az network vnet subnet create \ --resource-group myResourceGroup \ --vnet-name myVnet \ --name myVirtualNodeSubnet \ --address-prefixes 10.241.0.0/16
Create an AKS cluster with managed identity
Instead of using a system-assigned identity, you can also use a user-assigned identity. For more information, see Use managed identities.
You deploy an AKS cluster into the AKS subnet created in a previous step. Get the ID of this subnet using az network vnet subnet show:
az network vnet subnet show --resource-group myResourceGroup --vnet-name myVnet --name myAKSSubnet --query id -o tsv
Use the az aks create command to create an AKS cluster. The following example creates a cluster named myAKSCluster with one node. Replace
<subnetId> with the ID obtained in the previous step.
az aks create \ --resource-group myResourceGroup \ --name myAKSCluster \ --node-count 1 \ --network-plugin azure \ --vnet-subnet-id <subnetId> \
After several minutes, the command completes and returns JSON-formatted information about the cluster.
Enable virtual nodes addon
To enable virtual nodes, now use the az aks enable-addons command. The following example uses the subnet named myVirtualNodeSubnet created in a previous step:
az aks enable-addons \ --resource-group myResourceGroup \ --name myAKSCluster \ --addons virtual-node \ --subnet-name myVirtualNodeSubnet
Connect to the cluster
kubectl to connect to your Kubernetes cluster, use the az aks get-credentials command. This step downloads credentials and configures the Kubernetes CLI to use them.
az aks get-credentials --resource-group myResourceGroup --name myAKSCluster
To verify the connection to your cluster, use the kubectl get command to return a list of the cluster nodes.
kubectl get nodes
The following example output shows the single VM node created and then the virtual node for Linux, virtual-node-aci-linux:
NAME STATUS ROLES AGE VERSION virtual-node-aci-linux Ready agent 28m v1.11.2 aks-agentpool-14693408-0 Ready agent 32m v1.11.2
Deploy a sample app
Create a file named
virtual-node.yaml and copy in the following YAML. To schedule the container on the node, a nodeSelector and toleration are defined.
apiVersion: apps/v1 kind: Deployment metadata: name: aci-helloworld spec: replicas: 1 selector: matchLabels: app: aci-helloworld template: metadata: labels: app: aci-helloworld spec: containers: - name: aci-helloworld image: mcr.microsoft.com/azuredocs/aci-helloworld ports: - containerPort: 80 nodeSelector: kubernetes.io/role: agent kubernetes.io/os: linux type: virtual-kubelet tolerations: - key: virtual-kubelet.io/provider operator: Exists - key: azure.com/aci effect: NoSchedule
Run the application with the kubectl apply command.
kubectl apply -f virtual-node.yaml
Use the kubectl get pods command with the
-o wide argument to output a list of pods and the scheduled node. Notice that the
aci-helloworld pod has been scheduled on the
kubectl get pods -o wide
NAME READY STATUS RESTARTS AGE IP NODE aci-helloworld-9b55975f-bnmfl 1/1 Running 0 4m 10.241.0.4 virtual-node-aci-linux
The pod is assigned an internal IP address from the Azure virtual network subnet delegated for use with virtual nodes.
If you use images stored in Azure Container Registry, configure and use a Kubernetes secret. A current limitation of virtual nodes is that you can't use integrated Azure AD service principal authentication. If you don't use a secret, pods scheduled on virtual nodes fail to start and report the error
HTTP response status code 400 error code "InaccessibleImage".
Test the virtual node pod
To test the pod running on the virtual node, browse to the demo application with a web client. As the pod is assigned an internal IP address, you can quickly test this connectivity from another pod on the AKS cluster. Create a test pod and attach a terminal session to it:
kubectl run -it --rm testvk --image=mcr.microsoft.com/dotnet/runtime-deps:6.0
curl in the pod using
apt-get update && apt-get install -y curl
Now access the address of your pod using
curl, such as http://10.241.0.4. Provide your own internal IP address shown in the previous
kubectl get pods command:
curl -L http://10.241.0.4
The demo application is displayed, as shown in the following condensed example output:
<html> <head> <title>Welcome to Azure Container Instances!</title> </head> [...]
Close the terminal session to your test pod with
exit. When your session is ended, the pod is the deleted.
Remove virtual nodes
If you no longer wish to use virtual nodes, you can disable them using the az aks disable-addons command.
If necessary, go to https://shell.azure.com to open Azure Cloud Shell in your browser.
First, delete the
aci-helloworld pod running on the virtual node:
kubectl delete -f virtual-node.yaml
The following example command disables the Linux virtual nodes:
az aks disable-addons --resource-group myResourceGroup --name myAKSCluster --addons virtual-node
Now, remove the virtual network resources and resource group:
# Change the name of your resource group, cluster and network resources as needed RES_GROUP=myResourceGroup AKS_CLUSTER=myAKScluster AKS_VNET=myVnet AKS_SUBNET=myVirtualNodeSubnet # Get AKS node resource group NODE_RES_GROUP=$(az aks show --resource-group $RES_GROUP --name $AKS_CLUSTER --query nodeResourceGroup --output tsv) # Get network profile ID NETWORK_PROFILE_ID=$(az network profile list --resource-group $NODE_RES_GROUP --query ".id" --output tsv) # Delete the network profile az network profile delete --id $NETWORK_PROFILE_ID -y # Grab the service association link ID SAL_ID=$(az network vnet subnet show --resource-group $RES_GROUP --vnet-name $AKS_VNET --name $AKS_SUBNET --query id --output tsv)/providers/Microsoft.ContainerInstance/serviceAssociationLinks/default # Delete the service association link for the subnet az resource delete --ids $SAL_ID --api-version 2021-10-01 # Delete the subnet delegation to Azure Container Instances az network vnet subnet update --resource-group $RES_GROUP --vnet-name $AKS_VNET --name $AKS_SUBNET --remove delegations
In this article, a pod was scheduled on the virtual node and assigned a private, internal IP address. You could instead create a service deployment and route traffic to your pod through a load balancer or ingress controller. For more information, see Create a basic ingress controller in AKS.
Virtual nodes are often one component of a scaling solution in AKS. For more information on scaling solutions, see the following articles:
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