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K8s Upgrades

Performing upgrades of Amazon AKS Clusters is supported in the Controller


In Place Upgrades Notification

The administrator is shown a notification when an upgrade is available for a cluster. Clicking on the notification will provide the administrator with additional information on what is available.

  • A red banner indicates that the cluster is multiple versions behind the latest version
  • A blue banner indicates that the cluster is one version behind the latest version

Upgrade Notification


Scope of Upgrade

Two components need to be upgraded during an AKS Cluster upgrade

  1. AKS Control Plane
  2. Attached Node Groups (both Managed and Self Managed)

The Control plane always needs to be upgraded first before the node groups

Important

AKS Cluster upgrades performed by the controller are always performed in a manner where the cluster and resident workloads never encounter any downtime


Upgrade Everything

This is the default option. When selected, it upgrades everything to the new version of k8s i.e.

  • AKS Control Plane
  • All Node Pools (Both Managed and Self Managed)

Upgrade Default

Tip

Upgrading the entire AKS cluster can take ~15 minutes.

During the upgrade, an indication is provided to administrators on the main cluster list page. An illustrative example is shown below.

Cluster Upgrade Indication

Preflight Checks

A number of preflight checks are first performed before the upgrade is attempted

Upgrade AKS Control Plane

The AKS control plane is upgraded next. This can be a time-consuming step

Preflight Checks

Upgrade Node Pools

Node Pools are then upgraded to the selected version of k8s. Shown below is an example of an AKS Cluster's Upgrading Node pools progress

Upgraded Node pool

Post Upgrade Validations

Once upgrade is complete, a round of post-upgrade tests are performed to ensure that there are no loose ends and everything is as expected

Nodepool Provision complete

Once the Nodepool provision is complete, the status is shown in the Node Pools screen as Nodepool Provision Complete

Node Pool Upgrade Success


Control Plane Only Upgrade

Users can select Control Plane Only for upgrade. The attached node groups are left untouched. The administrators are allowed to upgrade the node groups individually one by one when required

Upgrade Control Plane Only


Node Pool Upgrade

This option is displayed to the administrator only if the controller detects that the node group is behind the AKS Control Plane from a Kubernetes version perspective.

  • Click the cluster name and select Node Pools tab
  • Click on upgrade notification for available node groups

Node Pool Upgrade

  • Select Upgrade to latest Image and click Upgrade Node Pool

Node Pool Image upgrade


Upgrade History

The Controller maintains the upgrade history associated with every upgrade action whether it was successful or not. Administrators can view the entire history through the following steps

  • Click the Cluster name and select Upgrade Jobs

This will display the entire history of upgrades for that specific cluster

Upgrade History

Upgrade Details

To view the detailed information of an upgrade, click the eye icon of that specific row. An illustrative example is shown below

Upgrade History Detail