AKS NAP: ZRS Disk PV Zone Fix with a Mutating Admission Webhook

This article addresses a scheduling problem in Azure Kubernetes Service (AKS) with Node Auto Provisioning (NAP/Karpenter) when using Azure Disk ZRS (Zone-Redundant Storage) Persistent Volumes with volumeBindingMode: Immediate. Pods get stuck in Pending state because Karpenter only evaluates the first NodeSelectorTerm, ignoring other zones. The author provides a temporary workaround using a Kubernetes mutating admission webhook that merges all zone values from separate NodeSelectorTerms into a single term, allowing Karpenter to correctly honor pod zone preferences. The article includes prerequisites (Go, Azure CLI, Terraform, kubectl, cert-manager), step-by-step instructions to provision the AKS NAP cluster, and notes that the fix is temporary until the upstream Karpenter PR is fully rolled out to AKS NAP.