Each server is its own StatefulSet with replicas: 1, its own ConfigMap and an explicit server_name, following the official ClickHouse Kubernetes operator’s choice of a StatefulSet per replica to avoid version-config mismatch mid-rollout. A single StatefulSet forces a choice between one mutable ConfigMap, which reaches old servers on any reload or crash-restart, and revision-named ConfigMaps, which give up hot reload; it also only ever removes its highest ordinal and cannot change its volume template in place. Per-server StatefulSets give per-server config, removal of a chosen server, and volume replacement one server at a time.
Considered options #
A single StatefulSet with updateStrategy: OnDelete (still one ConfigMap and one volume template), partition stepping (fixes the order), and owning pods and PVCs directly (reimplements identity and PVC retention).