Scale node pools in Azure Kubernetes Service (AKS)

As your application workload demands change, you might need to scale the number of nodes in a node pool in Azure Kubernetes Service (AKS). In this article, you learn how to manually and automatically scale node pools in AKS.

Prerequisites for AKS node pool scaling

• An existing AKS cluster with at least one node pool. If you need to create one, see Create an AKS cluster with node pools.
• You need the Azure CLI version 2.2.0 or later installed and configured. Run az --version to find the version. If you need to install or upgrade, see Install Azure CLI.

Scale a node pool manually

1. Scale the number of nodes in a node pool using the [az aks nodepool scale][az-aks-nodepool-scale] command. The --node-count flag specifies the desired number of nodes in the node pool. In this example, the node pool is scaled to five nodes.

   az aks nodepool scale \
       --resource-group <resource-group-name> \
       --cluster-name <cluster-name> \
       --name <node-pool-name> \
       --node-count 5 \
       --no-wait
   

2. Check the status of your node pools using the [az aks nodepool list][az-aks-nodepool-list] command.

   az aks nodepool list --resource-group <resource-group-name> --cluster-name <cluster-name>
   

   The following example output shows the node pool is in the Scaling state with a new count of five nodes:

   [
     {
       ...
       "count": 5,
       ...
       "name": "<node-pool-name>",
       "orchestratorVersion": "1.15.7",
       ...
       "provisioningState": "Scaling",
       ...
       "vmSize": "Standard_DS2_v2",
       ...
     },
     {
       ...
       "count": 2,
       ...
       "name": "<node-pool-name-2>",
       "orchestratorVersion": "1.15.7",
       ...
       "provisioningState": "Succeeded",
       ...
       "vmSize": "Standard_DS2_v2",
       ...
     }
   ]
   

   It takes a few minutes for the scale operation to complete. After the scale operation is complete, the node pool's provisioningState changes to Succeeded.

Scale a node pool automatically with the cluster autoscaler

You can use the cluster autoscaler with multiple node pools, and you can enable it on individual node pools and pass unique autoscaling rules to them.

• Enable the cluster autoscaler on an existing node pool using the [az aks nodepool update][az-aks-nodepool-update] command with the --update-cluster-autoscaler flag. The --min-count and --max-count flags specify the minimum and maximum number of nodes in the node pool. In this example, the cluster autoscaler is enabled with a minimum count of one node and a maximum count of five nodes:

  az aks nodepool update \
    --resource-group <resource-group-name> \
    --cluster-name <cluster-name> \
    --name <node-pool-name> \
    --update-cluster-autoscaler \
    --min-count 1 \
    --max-count 5
  

Next steps: Manage node pools in AKS

To learn more about managing node pools in AKS, see Manage node pools in Azure Kubernetes Service (AKS).