Istio mesh config, config cluster, remote cluster

 When a cluster contains istio custom resource definitions (CRDs) only, then that cluster is called istio config cluster. Which really just means the cluster at least contains Istio CRDs. A cluster can be just an Istio config cluster. If a cluster contains more than the CRDs, but also Istiod, then it is both config cluster and control plane. If a cluster really only contains Istio roles definitions such as istio-reader-clusterrole-external-istiod (that is the namespace) and clusterrolebinding (maybe the same name), and the mutating webhook configuration, most likely that cluster should be called remote istio cluster which should have been used for workload.