feat(global-router): read pool models from registrations, not a file

container/global-discovery-service.yaml

@@ -5,16 +5,23 @@
 # cluster (not through Karmada). Replace IMAGE with the pushed image, for example
 # from the repository root:
 #   sed "s#IMAGE#<registry>/global-discovery-service:<tag>#" container/global-discovery-service.yaml | kubectl apply -f -
-# It needs only read access to EndpointSlices. It lists the pools whose
-# `<DGD name>-pool-relay` Services Karmada imports, and the replicas of the
-# Global Router Service named by the --router-* arguments: set those to the
-# router's namespace, its Service and the port PoolRelays connect to.
+# It needs only read access to EndpointSlices. PoolRelays register their pools
+# with it (POST /pools), and it lists a pool while its registration is live and
+# Karmada imports a Ready endpoint of its `<DGD name>-pool-relay` Service. The
+# pool's frontends are the Ready endpoints of its `<DGD name>-frontend` Service,
+# exported the same way. It also lists the replicas of the Global Router
+# Service named by the --router-* arguments: set those to the router's
+# namespace, its Service and the port PoolRelays connect to.
 #
 # It reads the imported slices with the pod's credentials, so this cluster
-# needs a ServiceImport for each pool's PoolRelay Service and for the router
-# Service. To read the Karmada control plane instead, which holds every
-# exported Service's slices, mount its kubeconfig from a Secret, point
+# needs a ServiceImport for each pool's PoolRelay and frontend Services and for
+# the router Service. To read the Karmada control plane instead, which holds
+# every exported Service's slices, mount its kubeconfig from a Secret, point
 # KUBECONFIG at it, and grant the same read access there.
+#
+# With the default --registration-storage=memory, one instance keeps only the
+# registrations it receives, so run one, and have every PoolRelay register
+# with it.
 apiVersion: v1
 kind: Namespace
 metadata:

lib/global-discovery-service/src/backends.rs

@@ -6,4 +6,5 @@
 
 pub mod kubernetes;
 pub mod memory;
+pub mod registered;
 mod stream;

lib/global-discovery-service/src/backends/kubernetes.rs

@@ -11,10 +11,13 @@
 //!
 //! Each pool's PoolRelay Service, named `<DGD name>-pool-relay` by default,
 //! needs a `ServiceExport`, and so does the router's Service in the hub, so
-//! its replicas appear in every importing cluster. A pool is live while a
-//! PoolRelay endpoint is Ready. Its `relay_identities` are the addresses of
-//! every Ready PoolRelay pod, for routers on a trusted network to admit each
-//! of the pool's active-active replicas.
+//! its replicas appear in every importing cluster. Read alone, a pool is live
+//! while a PoolRelay endpoint is Ready. Its `relay_identities` are the
+//! addresses of every Ready PoolRelay pod, for routers on a trusted network to
+//! admit each of the pool's active-active replicas. The service also needs a
+//! live registration, which says what the pool serves
+//! ([`crate::backends::registered`]), and reads the pool's frontend addresses
+//! from its exported frontend Service, named `<DGD name>-frontend` by default.
 //!
 //! With Karmada, a Service name may have at most 55 characters: DGD names up
 //! to 44 with the default `-pool-relay` suffix. Karmada imports a Service as
@@ -33,10 +36,12 @@
 //! changed.
 //!
 //! ```ignore
+//! let registrations = Arc::new(MemoryPoolStore::new(lease));
+//! let imported = McsPoolDirectory::new(client.clone(), mcs, suffix, frontends)?;
 //! let backend = PoolDiscoveryBackend {
-//!     pools: Arc::new(McsPoolDirectory::new(client.clone(), mcs, suffix)),
+//!     pools: Arc::new(RegisteredPoolDirectory::new(Arc::new(imported), registrations.clone(), lease)),
 //!     routers: Arc::new(McsReplicaDirectory::new(client, &router, mcs)),
-//!     registrar: None,
+//!     registrar: Some(registrations),
 //! };
 //! service::serve(listener, backend, None, shutdown).await?;
 //! ```
@@ -47,5 +52,5 @@ mod hub;
 mod mcs;
 
 pub use endpoints::{ExportedService, McsReplicaDirectory};
-pub use hub::McsPoolDirectory;
+pub use hub::{FrontendService, McsPoolDirectory};
 pub use mcs::{KARMADA_MAX_SERVICE_NAME, McsImplementation};