Karpenter on AKS: Why is my subnet giving "SubnetIsFull" errors when it has 1000+ available IP addresses?

Question

Hello! I'm trying to run Karpenter to my AKS cluster in order to manage spot instances. I was able to get the service deployed to the cluster, but when I try to opt in a pod to Karpenter management with proper tolerations, I get the following error:

RESPONSE 400: 400 Bad Request
ERROR CODE: SubnetIsFull
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{"error": {"code": "SubnetIsFull", "message": "Subnet /subscriptions/

Answer 1

Hello Annabelle Taylor,

Thanks for your question

If your subnet is shared with other resources, the IPs might not be sufficient for AKS node pools. Karpenter might be trying to launch nodes in a wrong/undersized subnet. Can you verify?

kubectl logs -n karpenter -l app.kubernetes.io/name=karpenter

Also try the troubleshooting steps here: https://learn.microsoft.com/en-us/troubleshoot/azure/azure-kubernetes/create-upgrade-delete/error-code-subnetisfull

You can mark it 'Accept Answer' and 'Upvote' if this helped you

Regards,

Abiola