Wire the M6 KPI History recorder into the central composition path:
- Program.cs: call services.AddKpiHistory(configuration) on the central-only
branch alongside AddNotificationOutbox/AddAuditLog/AddSiteCallAudit.
- AkkaHostedService.cs: register KpiHistoryRecorderActor as a central,
non-role-scoped ClusterSingletonManager + ClusterSingletonProxy + a
PhaseClusterLeave CoordinatedShutdown graceful-stop drain (singleton name
'kpi-history-recorder'), copied/adapted from the audit-log-purge block.
- appsettings.Central.json (Host + docker + docker-env2 central nodes): add a
ScadaBridge:KpiHistory section (SampleInterval 00:01:00, RetentionDays 90,
PurgeInterval 1.00:00:00, DefaultMaxSeriesPoints 200).
KPI history is observability/best-effort and MUST NOT gate readiness: the
recorder is deliberately NOT added to RequiredSingletonsHealthCheck or any
other readiness gate.
REQ-HOST-4a lists "required cluster singletons running (if applicable)" as a
readiness criterion, but /health/ready only checked database + akka-cluster.
Add a third Ready-tagged check, RequiredSingletonsHealthCheck, registered in the
Central-role AddHealthChecks() chain (so it is naturally role-scoped — site nodes
never run it).
Probe: for each required central singleton, Ask its local ClusterSingletonProxy
an Identify with a short bounded per-singleton timeout (~2s, probes run
concurrently via Task.WhenAll). A non-null ActorIdentity.Subject within the
timeout means the singleton is running and reachable through the proxy; a null
subject or a timeout means unreachable → Unhealthy, naming the unreachable
singleton(s). The check never throws (catch-all → Unhealthy) and resolves
ActorSystem lazily from DI per probe (Unhealthy if Akka not yet up).
Required-always set = the five singleton proxies created unconditionally in
AkkaHostedService.RegisterCentralActors: notification-outbox, audit-log-ingest,
site-call-audit, audit-log-purge, site-audit-reconciliation. There are no
feature/config-gated central singletons today; any future gated singleton is the
"if applicable" case and must NOT be added to the required set.
Leadership-agnostic: the proxy reaches the singleton from either central node, so
a ready standby still reports ready (readiness must not require cluster
leadership — that is the Active tier's job). During a brief singleton handover the
probe may time out and the node flaps to not-ready, which is correct (a node
mid-handover is legitimately not fully ready); no retries, to keep the probe fast.
Tests (TDD): RequiredSingletonsHealthCheckTests exercises the probe against a
TestKit ActorSystem — all proxies present+reachable → Healthy; one missing →
Unhealthy naming it; ActorSystem absent → Unhealthy, no throw. HealthCheckTests
regression-guards the Ready tag + absence of the Active tag on the new check.
Per-probe health-check child scopes were disposing the AddTransient-bridged
ActorSystem (IDisposable), terminating the live cluster node ~4s after boot and
leaving every singleton-proxy Ask to hang the full 30s QueryTimeout — the central
report pages (/notifications, /site-calls, /monitoring/health) loaded in ~30s.
Bridge it as a singleton via a new lazy AkkaHostedService.GetOrCreateActorSystem()
so child-scope disposal never touches it. Verified: 0 post-startup terminates,
healthy active/standby, report pages ~0.05s, Playwright 68 passed / 0 failed.
Renames the 13 SCADALINK_* runtime env vars → SCADABRIDGE_*, the ScadaLink__
.NET config keys → ScadaBridge__, the stale ScadaLink.Host.exe assembly name
→ ZB.MOM.WW.ScadaBridge.Host.exe, the scadalink_app SQL login → scadabridge_app,
and residual identifiers/comments/docs. Migration records (prior rename
tooling/design, DB-rename helper, this scrub script) carved out.
Adds tools/scrub-scadalink-refs.sh.
Joseph Doherty