If upstream is a k8s service, you can binding the upstream to the k8s service.
So when the pod Ip of the k8s service updated, edge will update the node Ip of the upstream automatically
When you create upstream, select Use Kubernetes Service.
And then select k8s cluster, namespace, service and port. Click Save button.
Save success, admin will auto discovery k8s service pod, and add it to upstream.
add pod number to 3, fresh ui, you will find the node of the upstream is updated.