Cluster discovery service (CDS)
The cluster discovery service (CDS) is an optional API that Envoy will call to dynamically fetch cluster manager members. Envoy will reconcile the API response and add, modify, or remove known clusters depending on what is required.
Any clusters that are statically defined within the Envoy configuration cannot be modified or removed via the CDS API.
CDS has a statistics tree rooted at cluster_manager.cds.