Plan a highly available AKS cluster managed with Terraform

You want to create an Azure Kubernetes cluster repeatedly, without clicking through the same setup by hand. Terraform describes infrastructure in configuration files, shows a proposed change and then asks the provider to make it. Azure Kubernetes Service (AKS) supplies managed Kubernetes in Azure.

Use Terraform when you need reviewable, repeatable cluster configuration. A successful run means the requested infrastructure was created; it does not prove the application will survive a failed node or unavailable zone. High availability also needs enough application copies, suitable data storage and a tested recovery procedure.

This guide connects those decisions before you apply a configuration. The original article was not recovered, and Kubedex has not deployed a universal highly available AKS module for this replacement guide.

Define the availability requirement

Specify the tolerated node, zone or regional failure and the recovery objective. Confirm which capabilities and VM sizes are available in the target region. Plan application replicas, topology, disruption budgets and storage placement alongside the cluster's control-plane and node-pool configuration. A resilient control plane cannot compensate for a single application replica with a single failure-prone data dependency.

Make the Terraform state reliable

Choose an access-controlled remote state backend and a process that prevents concurrent changes. Treat state as sensitive because infrastructure values can contain secrets. Pin provider and module versions and review the plan for replacements, not only additions. Keep cluster provisioning separate from application credentials and routine application release ownership.

1. Agree on subscription, resource-group, network, DNS and identity boundaries before creation.
2. Choose system and workload node-pool responsibilities, autoscaling limits and upgrade capacity.
3. Review egress and private-access requirements so nodes and controllers can reach their required services.
4. Create a disposable test environment and review both the plan and the resulting Azure resources before adopting the configuration.

Verify failure and upgrade behavior

Exercise a node drain, a workload rollout, unavailable dependency behavior and recovery from backup. Confirm that resource requests and scheduling constraints allow replicas to move. Rehearse a supported Kubernetes upgrade and check that Terraform detects and resolves expected drift without proposing accidental replacement.

Rollback has several layers

Restoring a prior Terraform file is not a universal undo. Some platform upgrades and data changes require forward recovery or a new environment. Record what can be reverted in place, what must be restored from backup and which operations require a controlled migration.

This page is a design checklist; Kubedex has not provisioned an Azure subscription or validated a universal HA module. The managed-cluster comparison covers the broader ownership decision.