Add high-availability cluster support to the embedded NATS server
(issue 0003a, first phase of decentralization).
pkg/embeddednats:
- ServerConfig gains ServerName (unique per node, required by JetStream
RAFT) and an optional *ClusterConfig (cluster name, route host/port,
peer route URLs, shared-secret Username/Password, and a mutual-TLS
*tls.Config). applyClusterOpts maps it onto server.Options.Cluster +
Routes. Nil Cluster keeps the legacy standalone server.
pkg/busauth:
- RouteTLSConfig builds the route layer's mutual-TLS config: the node
presents its CA-signed certificate AND verifies the peer's certificate
against the bus CA (RequireAndVerifyClientCert), reusing the issue-0001
CA. Routes authenticate NODES, never the client nkey authenticator.
cmd/membershipd:
- Cluster flags (--cluster-name/--server-name/--cluster-port/--routes/
--cluster-user/--cluster-pass/--route-tls-cert/-key/-ca) wire a node
into the cluster. validateClusterConfig refuses a public cluster
without a route secret and complete mutual route TLS, and rejects
partial route-TLS flags (all-or-nothing). splitRoutes parses the CSV.
Tests (DoD: golden + 2 edge + error path):
- TestClusterForwardsAcrossNodes: 2-node cluster forwards a client
subject from one node to a subscriber on the other.
- TestClusterThreeNodesForward: 3-node (HA shape) cross-node forwarding.
- TestClusterMutualTLSForwards: forwarding over mutual-TLS routes.
- TestClusterRejectsBadRouteAuth: wrong cluster password -> no route.
- TestClusterRejectsUnsignedNode: cert not signed by the bus CA -> no route.
- TestClusterConfigPolicy / TestSplitRoutes: boot-guard + CSV parsing.
Master stays green: standalone (no --cluster-name) is unchanged.
agent