As EKS tracks upstream Kubernetes that means that customers can, and should, regularly upgrade their EKS so as to stay within the project’s upstream support window. This used to be the current version and two version back (n-2) - but it was recently extended to three versions back (n-3).
There is a new major version of Kubernetes every quarter which means that the Kubernetes support window has now gone from three quarters of a year to one full year.
In addition to upgrades to Kuberentes, there are other related upgrades to think about with your cluster as well:
In this Chapter you’ll follow the AWS suggested process to upgrade your cluster from 1.20 to 1.21 including its Managed Node Group to get first-hand experience with this process and where EKS and Managed Node Groups help.