Catégorie : Kubernetes (AKS)

AKS | Scale-down Mode to delete/deallocate nodes in Azure Kubernetes Service (AKS)

Hi!

By default, scale-up operations performed manually or by the cluster autoscaler require the allocation and provisioning of new nodes, and scale-down operations delete nodes. Scale-down Mode allows you to decide whether you would like to delete or deallocate the nodes in your Azure Kubernetes Service (AKS) cluster upon scaling down.

When an Azure VM is in the Stopped (deallocated) state, you will not be charged for the VM compute resources. However, you will still need to pay for any OS and data storage disks attached to the VM. This also means that the container images will be preserved on those nodes.

Limitations:

  • Ephemeral OS disks are not supported
  • Spot node pools are not supported
# Install the aks-preview extension
az extension add --name aks-preview

# Update the extension to make sure you have the latest version installed
az extension update --name aks-preview

az feature register --namespace "Microsoft.ContainerService" --name "AKS-ScaleDownModePreview"
az feature list -o table --query "[?contains(name, 'Microsoft.ContainerService/AKS-ScaleDownModePreview')].{Name:name,State:properties.state}"

# In this example, we create a new node pool with 20 nodes and specify that upon scale-down, nodes are to be deallocated via --scale-down-mode Deallocate
az aks nodepool add --node-count 20 --scale-down-mode Deallocate --node-osdisk-type Managed --max-pods 10 --name nodepool2 --cluster-name myAKSCluster --resource-group myResourceGroup

# By scaling the node pool and changing the node count to 5, we will deallocate 15 nodes
az aks nodepool scale --node-count 5 --name nodepool2 --cluster-name myAKSCluster --resource-group myResourceGroup

# Deleting previously deallocated nodes
az aks nodepool update --scale-down-mode Delete --name nodepool2 --cluster-name myAKSCluster --resource-group myResourceGroup

# The default behavior of AKS without using Scale-down Mode is to delete your nodes when you scale-down your cluster. Using Scale-down Mode, this can be explicitly achieved by setting --scale-down-mode Delete
az aks nodepool add --enable-cluster-autoscaler --min-count 1 --max-count 10 --max-pods 10 --node-osdisk-type Managed --scale-down-mode Delete --name nodepool3 --cluster-name myAKSCluster --resource-group myResourceGroup

Maxime.

AKS | Update the Service Principal Credentials

Hi,

In this article, I will show you how you can update the service principals of your AKS cluster.

Check the expiration of your service principal:

SP_ID=$(az aks show --resource-group myResourceGroup --name myAKSCluster \
--query servicePrincipalProfile.clientId -o tsv)
az ad sp credential list --id "$SP_ID" --query "[].endDate" -o tsv

Update the service principal:

az aks update-credentials \
--resource-group myResourceGroup \
--name myAKSCluster \
--reset-service-principal \
--service-principal $SP_ID \
--client-secret $SP_SECRET

Update the AKS cluster with the new AAD Application credentials:

az aks update-credentials \
--resource-group myResourceGroup \
--name myAKSCluster \
--reset-aad \
--aad-server-app-id \
--aad-server-app-secret \
--aad-client-app-id

Maxime.

AKS | Private Cluster RunCommand

Hi!

Today when you need to access a private cluster, you must do so within the cluster virtual network or a peered network or client machine. This usually requires your machine to be connected via VPN or Express Route to the cluster virtual network or a jumpbox to be created in the cluster virtual network.

AKS run command allows you to remotely invoke commands in an AKS cluster through the AKS API. This feature provides an API that allows you to, for example, execute just-in-time commands from a remote laptop for a private cluster. This can greatly assist with quick just-in-time access to a private cluster when the client machine is not on the cluster private network while still retaining and enforcing the same RBAC controls and private API server.

az feature register --namespace "Microsoft.ContainerService" --name "RunCommandPreview"

az feature list -o table --query "[?contains(name, 'Microsoft.ContainerService/RunCommandPreview')].{Name:name,State:properties.state}"

az provider register --namespace Microsoft.ContainerService

az aks command invoke -g <resourceGroup> -n <clusterName> -c "kubectl get pods -n kube-system"

Maxime.