I am planning to upgrade the kubernetes version of AWS EKS from 1.15 to 1.16. I understood that there is no downtime while upgrading the cluster plane of the kubernetes. But I am not sure if there is a downtime while upgrading the worker nodes of the kubernetes.
Is there any downtime while upgrading the kubernetes version?
It depends on how you have deployed your workload on the cluster and how you are planning to upgrade the worker nodes. Note the following items
https://kubernetes.io/docs/tasks/administer-cluster/safely-drain-node/