About AKS version and support policy

The Kubernetes community releases minor versions roughly every three months. Recently, the Kubernetes community has increased the support window for each version from 9 months to 12 months, starting with version 1.19

Major versions change when incompatible API updates or backwards compatibility may be broken. Minor versions change when functionality updates are made that are backwards compatible to the other minor releases. Patch versions change when backwards-compatible bug fixes are made.

Support Policy in Mooncake

How to up grade AKS

https://docs.azure.cn/en-us/aks/upgrade-cluster az aks upgrade
--resource-group myResourceGroup
--name myAKSCluster
--kubernetes-version KUBERNETES_VERSION

Details

• add a new buffer node (or as many nodes as configured in max surge) to the cluster that runs the specified Kubernetes version.
• cordon and drain one of the old nodes to minimize disruption to running applications (if you're using max surge it will cordon and drain as many nodes at the same time as the number of buffer nodes specified).
• When the old node is fully drained, it will be reimaged to receive the new version and it will become the buffer node for the following node to be upgraded.
• This process repeats until all nodes in the cluster have been upgraded.
• At the end of the process, the last buffer node will be deleted, maintaining the existing agent node count and zone balance.