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feat(localdb): wire 2-node replication for the site database, default OFF

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Task 7 of the LocalDb Phase 1 adoption plan.

AddZbLocalDbReplication registers the engine; MapZbLocalDbSync exposes the
passive endpoint the peer node dials. Both are unconditional but INERT by
default: with no LocalDb:Replication:PeerAddress the initiating
SyncBackgroundService starts and immediately idles, and nothing dials the
endpoint. A site pair replicates only once an operator sets a peer on BOTH
nodes. The endpoint shares the Kestrel h2c listener the site gRPC server already
uses, so there are no listener or port changes.

Deviation from the plan: it put AddZbLocalDbReplication in Program.cs. Doing so
would have left it untested - the composition-root tests build
SiteServiceRegistration's graph, not Program.cs - so a registration that silently
went missing would still show green. It now sits next to AddZbLocalDb in
SiteServiceRegistration, where the DI-graph tests actually cover it.
MapZbLocalDbSync stays in Program.cs because it needs the WebApplication.

Two pins added to SiteLocalDbWiringTests, which configures no peer:
  - the engine resolves and is idle (not connected, no peer, never synced) -
    default-off means inert, not unregistered;
  - OplogBacklog is 0, not null. It is deliberately nullable so a failed poll
    reads as "unknown" instead of a healthy zero; a real 0 proves the provider is
    wired to the oplog, which Task 9's health signal depends on.

Inbound auth on the sync endpoint is Task 8. Until that lands the endpoint is
unauthenticated - which is precisely why replication ships default-OFF and no
config in this repo sets a peer.

Verified: build 0 warnings; Host 296/296, SiteEventLogging 70/70,
SiteRuntime 530/530, Commons 684/684, Communication 312/312.

Claude-Session: https://claude.ai/code/session_01BL2Vu1ESDQ9SCN4gVKkdts
This commit is contained in:
Joseph Doherty
2026-07-19 09:15:26 -04:00
parent 0d8a80aa27
commit a560e9eaf9
3 changed files with 54 additions and 3 deletions
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src/ZB.MOM.WW.ScadaBridge.Host/SiteServiceRegistration.cs
+13 -2
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@@ -15,6 +15,7 @@ using ZB.MOM.WW.ScadaBridge.SiteEventLogging;
using ZB.MOM.WW.ScadaBridge.SiteRuntime;
using ZB.MOM.WW.ScadaBridge.StoreAndForward;
using ZB.MOM.WW.LocalDb;
using ZB.MOM.WW.LocalDb.Replication;
using ZB.MOM.WW.Secrets.DependencyInjection;
using ZB.MOM.WW.Telemetry;
@@ -56,12 +57,22 @@ public static class SiteServiceRegistration
//
// Storage is registered UNCONDITIONALLY and needs no flag: with no peer
// configured, LocalDb is simply a local SQLite file and the replication
// initiator idles. Replication itself is opt-in via LocalDb:Replication:PeerAddress
// and is wired in Program.cs, which owns the gRPC host the sync endpoint needs.
// initiator idles.
//
// Design: scadaproj docs/plans/2026-07-19-scadabridge-localdb-design.md
services.AddZbLocalDb(config, SiteLocalDbSetup.OnReady);
// The replication engine, likewise unconditional but INERT by default: with no
// LocalDb:Replication:PeerAddress the initiating SyncBackgroundService starts and
// immediately idles, and nothing dials the passive endpoint. A site pair
// replicates only once an operator sets a peer on both nodes.
//
// Registered HERE rather than in Program.cs (where the plan first put it) so the
// composition-root tests, which build this graph and not Program.cs, actually
// cover it. The endpoint half — MapZbLocalDbSync — has to stay in Program.cs
// because it needs the WebApplication.
services.AddZbLocalDbReplication(config);
services.AddDataConnectionLayer();
// Local SQLite store by default; a local store replicating against a shared SQL-Server hub
// only when Secrets:Replication:Enabled is true AND a hub connection string is present.