IOpcUaEndpointState (review-remediation lane C3) recorded whether the SDK started, but only the
health check read it: a fused node whose endpoint failed (port 4840 taken, ...) still advertised
250/240 and stayed driver Primary, so the Primary-gated data plane ran on a node no client could
reach while the reachable peer refused writes as Secondary.
- Move IOpcUaEndpointState/OpcUaEndpointState/OpcUaEndpointStatus from Host to Commons.OpcUa so
the Runtime can consume it.
- ServiceLevelCalculator: new NodeHealthInputs.EndpointListening (default true). false -> 0,
ahead of every other input including the +10 Primary bonus.
- OpcUaPublishActor: takes the endpoint state, feeds EndpointListening (Failed only; NotStarted /
Stopped are boot/shutdown windows) on the DB-backed and DB-less paths, and the legacy role-only
seam returns 0 for a failed endpoint too.
- New OpcUaEndpointStepDownActor (one per driver node): a Primary (ClusterActiveNode.SelfIsActive,
the election's own primitive) with a Failed endpoint gracefully Leaves its mesh - the manual
failover mechanism - so the peer becomes the oldest Up driver member, hosts the singletons and is
Primary. The election itself is not bent. Guarded on a peer having recently reported its own
endpoint listening (EndpointReport on the new opcua-endpoint-state DPS topic), so a pair with
both endpoints failed does not bounce the role and restart nodes forever, and a lone node never
shuts itself down.
- Runtime now references ZB.MOM.WW.Health.Akka (ClusterActiveNode).
- Docs: Redundancy.md tier table + new "Endpoint start failure: Primary step-down" section;
cluster-topology rule; HealthEndpoints / OpcUaEndpointHealthCheck comments (F-C1 landed).
Tests: ServiceLevelCalculatorTests (+5), OpcUaPublishActorEndpointStateTests (7: DB-less,
DB-backed, legacy seam, NotStarted/Stopped do not demote, a later failure demotes on the next
tick), OpcUaEndpointStepDownActorTests (3, real two-node mesh: holds while the peer is not
listening then leaves and the peer becomes Primary; failed Secondary and healthy Primary never
leave). Each was mutation-checked: removing the calculator/legacy guard, the Leave, the
peer-listening guard or the Primary guard fails the corresponding tests.
RedundancyStateActor derived the driver Primary from ClusterState.RoleLeader("driver").
Akka offers two different notions of a "first" member and they are not the same
one: role leader is the lowest-ADDRESSED Up member (host, then port), while
ClusterSingletonManager places singletons on the OLDEST — lowest up-number.
They agree on a freshly-formed cluster, which is why every existing test passed.
They diverge after any restart: the restarted node re-joins as the youngest while
keeping its address, so if it holds the lower address it becomes role leader while
the singletons stay put. The snapshot would then name a Primary that is not
hosting the work, and every Primary-gated surface follows it — inbound device
writes, native-alarm acks, the fleet-wide alerts emit, and the alarm-history
drain would all enable on the wrong node while the node actually running the
singletons stayed gated off.
BuildSnapshot now selects the oldest Up member carrying the driver role, matching
singleton placement. Leaving members are excluded: a node handing its singletons
over must not be named Primary.
NodeRedundancyState.IsRoleLeaderForDriver is renamed IsDriverPrimary, and
NodeHealthInputs.IsDriverRoleLeader likewise. Keeping the old names would have
left the wire contract asserting a derivation the code no longer uses — the same
drift that made this defect invisible.
Proven by a real two-node cluster rather than a mock. RedundancyPrimaryElectionTests
binds the first-joining node to the HIGHER port, so oldest and lowest-address name
different nodes, and includes a fixture assertion that the divergence actually
occurred — without it the real assertion could pass for the wrong reason. Positive
control: restoring the RoleLeader derivation turns exactly the two election tests
red while the fixture check stays green.
Runtime.Tests 440 passed, ControlPlane.Tests 82, Cluster.Tests 36.
Claude-Session: https://claude.ai/code/session_01GASWkNEi68FSCtvr6rLoEW
Code review at HEAD 7286d320. Cluster-001 (SeedFromCurrentState reads from one
snapshot), Cluster-003 (HoconLoader double-dispose), Cluster-004 (stale akka.conf
header), Cluster-005 (ServiceLevelCalculator tests added to Cluster.Tests). Cluster-002
deferred (no production caller).
Joseph Doherty