AKS is nodepool is not creating nodes in availability zone 1

Question

I have enabled zones 1, 2 and 3 and we are using availability zones in AKS.

But the cluster is not provisioning nodes in zone 1.

What could be the problem?

Answer 1

Hi Jean-Pierre Fouche,

Welcome to the Microsoft Q&A Platform! Thank you for asking your question here.

I could provide you with the below troubleshooting steps:

• Please verify that you used the --zones parameter correctly when creating the cluster. If you omitted Zone 1 or specified it incorrectly, nodes will not be allocated there. Double-check your deployment templates or scripts to confirm that zone 1 is specified correctly. The command should look like this:

    az group create --name $RESOURCE_GROUP --location $LOCATION
    az aks create \ --resource-group $RESOURCE_GROUP \ --name $CLUSTER_NAME \ --generate-ssh-keys \ --vm-set-type VirtualMachineScaleSets \ --load-balancer-sku standard \ --node-count 3 \ --zones 1 2 3
  

• As anrodrigues-MSFT mentioned, please ensure that the VM size (SKU) you selected for your AKS nodes is available in all specified availability zones. If the VM size you selected for your AKS nodes is not available in Zone 1, Azure will not provision nodes there. You can check the availability of SKUs in specific zones through the Azure portal or CLI commands.

az vm list-sizes --location eastus2 --output table

• If you are using multiple node pools, make sure that each node pool is correctly configured to use the desired zones. Sometimes, node pools might not be evenly distributed across zones due to misconfiguration.
• Verify node distribution across zones:

az aks get-credentials --resource-group $RESOURCE_GROUP --name $CLUSTER_NAME
kubectl describe nodes | grep -e "Name:" -e "topology.kubernetes.io/zone"

This will help you see which zones your nodes are currently assigned to.
https://learn.microsoft.com/en-us/azure/aks/availability-zones#verify-node-distribution-across-zones

Additional resources: https://learn.microsoft.com/en-us/azure/aks/availability-zones-overview

If you have any further queries, do let us know.

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Answer 2

Hi All,
Thank you for your replies.

Our cluster has been working OK until today. So this is not an issue about parameters during cluster creation @Mounika Reddy Anumandla

Here are the zones available on our nodes:

kubectl get no -ojson | jq -r '.items[] | "\(.metadata.name) \(.metadata.labels["topology.kubernetes.io/zone"])"' | column -t

aks-monitoring-22598778-vmss000000 0

aks-monitoring-22598778-vmss000001 0

aks-monitoring-22598778-vmss000007 0

Further, please see the command below:

az vm list-skus --location "west us" --size "Standard_E2as_v5" --resource-type virtualMachines | jq -r '.[].locationInfo[].zones'

[] # <===== NO ZONES AVAILABLE FOR THIS SKU

I would be grateful if you could provide an answer?

Many Thanks

Answer 3

Hi @anrodrigues-MSFT @Mounika Reddy Anumandla

FYI we are operating in region us west

Our VM Sku for the node pool is Standard_E2as_v5