Azure AKS Cluster Upgrade for a National Certification Board

The organization's Azure Kubernetes Service cluster was running on a deprecated Kubernetes version and urgently required an upgrade to maintain vendor support and security compliance. However, two critical blockers prevented the upgrade: the existing subnet's CIDR range had insufficient IP addresses to provision new nodes during the rolling upgrade process, and Azure lacked sufficient regional capacity for the VM SKU assigned to their node pools. Without resolution, the cluster would fall out of compliance and lose access to critical security patches.

We executed a multi-phase remediation strategy. First, we performed a thorough analysis of the existing subnet utilization and AKS networking requirements, calculating the exact IP headroom needed for a safe rolling upgrade. We then expanded the virtual network by provisioning a new, larger subnet with adequate CIDR allocation and migrated the AKS cluster's node pools to the expanded address space. Simultaneously, we identified the VM SKU capacity constraint by working through Azure's available compute options in the region, selecting an equivalent-performance SKU with full availability. We migrated workloads to the new node pool configuration, validated all services, and completed the Kubernetes version upgrade — all with zero application downtime.

“Our AKS upgrade had been stalled for months due to infrastructure constraints that our internal team couldn't resolve. Barista Labs diagnosed both issues quickly, laid out a clear remediation plan, and executed the entire migration and upgrade with zero downtime. We're now fully compliant and positioned for future growth.”