How to upgrade an AKS cluster created by pltf.

Overview

AKS does not auto-upgrade clusters by default. Upgrade one minor version at a time and validate workloads between steps.

Step 1: Control plane

1. Inspect available versions:

   az aks get-upgrades --name <cluster> --resource-group pltf-<env>
   

2. Upgrade the control plane:

   az aks upgrade --name <cluster> --resource-group pltf-<env> --kubernetes-version <version>
   

Step 2: Node pools

Upgrade each node pool after the control plane:

az aks nodepool upgrade \
  --resource-group pltf-<env> \
  --cluster-name <cluster> \
  --name <node-pool> \
  --kubernetes-version <version>

Step 3: Pin versions in specs

Update your spec so future applies stay consistent:

modules:
  - id: aks
    type: azure_aks
    inputs:
      kubernetes_version: "1.28.3"

pltf terraform plan -f env.yaml -e prod
pltf terraform apply -f env.yaml -e prod

Notes

• Review API deprecations and add-on compatibility before upgrading.
• Upgrade node pools one at a time to reduce impact.

References

• AKS upgrades: https://learn.microsoft.com/azure/aks/upgrade-cluster