Clusters in a namespace can be put into a cluster group. A cluster group is essentially a named selector. The only parameter for a cluster group is essentially the selector. When you get to a certain scale cluster groups become a more reasonable way to manage your clusters. Cluster groups serve the purpose of giving aggregated status of the deployments and then also a simpler way to manage targets.
A cluster group is created by creating a
ClusterGroup resource like below
# This is the standard metav1.LabelSelector format to match clusters by labels