- Prepare for the Upgrade
- Review Release Notes: Before initiating an upgrade, review the Kubernetes release notes to understand the changes, deprecations, and new features.
- Backup Your Data: Although the upgrade process is designed to be safe, ensure that you have backups of your data and application configurations.
- Check Cluster Health: Ensure that the cluster is in a healthy state. You can do this by running
kubectl get nodes
andkubectl get pods --all-namespaces
to ensure that there are no issues.
- Plan the Upgrade
- Select the Target Version: Decide which Kubernetes version you want to upgrade to. AKS supports upgrading to a newer minor or patch version.
- Review Node Pool Upgrades: If you have multiple node pools, plan the upgrade for each pool, keeping in mind that the upgrade process is performed sequentially, not in parallel.
- Upgrade the Cluster Control Plane
- Initiate Control Plane Upgrade: Start by upgrading the AKS control plane. This can be done through the Azure portal, Azure CLI, or PowerShell.
az aks upgrade --resource-group <ResourceGroupName> --name <ClusterName> --kubernetes-version <KubernetesVersion>
- The control plane upgrade is a managed process, meaning Azure will handle the upgrade and any necessary restarts automatically.
- Upgrade Node Pools
- Upgrade Node Pools Individually: After the control plane is upgraded, proceed to upgrade the node pools. This can also be done via the Azure portal, Azure CLI, or PowerShell.
az aks nodepool upgrade --resource-group <ResourceGroupName> --cluster-name <ClusterName> --name <NodePoolName> --kubernetes-version <KubernetesVersion>
- Rolling Upgrade: AKS performs a rolling upgrade for the nodes, meaning nodes are upgraded one by one. This helps maintain high availability during the upgrade process.
- Monitor the Upgrade Process
- Monitor Node Status: During the upgrade, monitor the node status using
kubectl get nodes
to see when nodes are drained, upgraded, and returned to service. - Monitor Workloads: Ensure that your workloads are rescheduled onto upgraded nodes and that there are no issues with pod restarts or failures.
- Post-Upgrade Validation
- Validate Cluster Functionality: After the upgrade is complete, validate that the cluster is functioning as expected. Check the status of all nodes and pods to ensure that they are healthy.
- Test Applications: Perform tests on your applications to ensure they are running correctly with the new Kubernetes version.
- Update Dependencies: If necessary, update any cluster dependencies, such as Helm charts or third-party tools, to versions compatible with the upgraded Kubernetes version.
- Cleanup and Final Checks
- Clean Up Resources: If any temporary resources or configurations were created during the upgrade process, ensure they are cleaned up.
- Update Documentation: Update your operational documentation to reflect the new Kubernetes version and any changes made during the upgrade process.
- Set Up Alerts: Re-enable any alerts or monitoring that may have been paused during the upgrade process.
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hth
Marcin