ClusterClient→gRPC migration Phase 4 (docs/plans/2026-07-22-clusterclient-to-grpc-plan.md).
Phases 2/3 proved both directions on gRPC; this removes the Akka transport underneath.
Deleted:
- AkkaCentralTransport, AkkaSiteTransport (+ their dedicated tests)
- ISiteClientFactory + DefaultSiteClientFactory; CentralCommunicationActor legacy
ctor + SelectTransport (Host now builds GrpcSiteTransport and injects it)
- ClusterClient creation + both ClusterClientReceptionist.RegisterService calls in
AkkaHostedService; the RegisterCentralClient message + receive block
- CommunicationOptions.CentralContactPoints; the CentralTransport/SiteTransport
coexistence flags; the CentralTransportMode/SiteTransportKind enums
gRPC is now the only site↔central transport (site→central CentralControlService via
GrpcCentralTransport; central→site SiteCommandService via GrpcSiteTransport), both
built unconditionally by the Host. NoOpCentralTransport is the fail-loud null-default
so TestKit command-dispatch suites still construct the site actor without a wired
transport; production always injects GrpcCentralTransport.
Config: CentralGrpcEndpoints is now unconditional — CommunicationOptionsValidator
rejects blank entries (role-agnostic), and StartupValidator requires a Site node to
list >=1 endpoint (fail-fast, mirrors GrpcPsk). Rig configs moved
CentralContactPoints -> CentralGrpcEndpoints (docker x6, docker-env2 x2, Host default,
deploy/wonder-app-vd03). Kept Akka.Cluster.Tools (ClusterSingleton still used).
Tests: build 0/0; Communication.Tests 640, Host.Tests 421 green. Removed the
ClusterClient.Send per-site-routing tests (covered by the transport suites), swapped
the ISiteClientFactory-based ctors to a substitute ISiteCommandTransport, converted
the audit-push integration relay to an in-process bridge transport.
Docs: Component-Communication/Host/StoreAndForward, components/Communication,
topology-guide, grpc_streams (SUPERSEDED note), the frame-size known-issue (retired
amendment), and CLAUDE.md transport decisions.
Not included: the dead IntegrationCallRequest path (#32) is a separate user-owned
behavioral decision — SiteEnvelope routing is transport-agnostic so it still compiles.
Central flipped to SiteTransport=Grpc (both nodes, central-wide flag), sites
kept on gRPC from Phase 2 → both directions on gRPC at once. Central logs
'central→site command transport: gRPC (SiteCommandService)'; 0 ClusterClient-to-
site on either central.
Command matrix over SiteCommandService (all 200):
- ExecuteQuery (event-log) + ExecuteParked (parked) — all 3 sites
- ExecuteLifecycle disable/enable #95 on site-a — NEW live coverage vs 1B/P2
(SoakNotify instances survived the recreate as Enabled)
Resilience:
- hard-kill the ACTIVE site-a node mid-query-loop → in-flight call returned
TIMEOUT at exactly the 30s QueryTimeout deadline (bounded, no hang; deadline≠
retry — an in-flight call can't be safely re-sent)
- next + all subsequent queries recovered automatically via site-a-b
(SitePairChannelProvider NodeA→NodeB); site→central S&F never stopped
(notif 619→715, still no dupes)
- 0 PermissionDenied across all 8 nodes
ExecuteOpcUa/ExecuteRoute/TriggerFailover deferred (no OPC-bound instance / no
CLI verb; unit-proven). Rig left both-gRPC; git reverted to Akka default.
All 6 site nodes flipped to CentralTransport=Grpc; whole control plane
(heartbeat/health/notification S&F/audit) rides gRPC CentralControlService,
196 RPCs/90s 0 non-200, 0 PermissionDenied, 0 health-sequence regressions.
Soak driven by a live SoakNotify workload (3 instances, 3 notifs/5s):
- single-node active-kill (central-a): sticky failover central-a:8083→b:8083
logged instantly, central-b active in 29s, buffer drained 72→101, every 5s
bucket = exactly 3 through the gap, 101==101 distinct
- failback: central-a rejoined ready ~5s as standby, central-b kept active
(oldest-Up, no flap), traffic uninterrupted
- full outage (both central down ~59s): count frozen, cold re-form central-b
active ~14s, ~42 buffered drained, every 5s bucket = exactly 3 across the
whole dead window, 216==216 distinct — zero loss, zero dupes
Also previews Phase 5 checks 4 (failover/failback) and 5 (mid-drain kill).
Rig config reverted to Akka default (defaults stay Akka until Phase 4).
Phase 0's gate doc now carries the full suite picture, not just the rig checks.
Playwright: 170 pass / 2 fail / 1 skip of 173. Both failures were run down to
root cause and both are pre-existing on main, unrelated to this branch (which
touches no EF, CentralUI, Transport or ManagementService file):
- TransportImportTests is a REAL production bug: BundleImporter.cs:1298 opens a
user-initiated transaction while the central context has EnableRetryOnFailure,
so SqlServerRetryingExecutionStrategy refuses the split query inside it and
bundle import fails against real MS SQL. The unit/integration suite cannot see
it -- the in-memory EF provider has no retrying strategy and BeginTransaction
is a no-op there.
- SmsNotificationE2ETests is a stale fixture: SID 'ACtest123' (2026-06-19) vs the
^AC[0-9a-fA-F]{32}$ guard added 2026-07-10 (40088a21). Failing since then, which
has also silenced everything after the toast assertion -- including the
secret-non-leak check on the Auth Token.
Also records that the earlier 44-failure run is void: a concurrent deploy.sh was
recreating the cluster underneath it.
Neither is fixed here; both are out of scope for a PSK-auth branch.
The gate's first run failed on a defect the green suite could not see: two public
constructors on ControlPlaneAuthInterceptor made Grpc.AspNetCore's activation
throw per call, so correct key, wrong key and no key all produced identical
errors. Recorded in full because the symptom (Unknown / "Exception was thrown by
handler") points at the handler, not at auth, and because phases 1A/1B both add
services to this same interceptor — they must extend DefaultGatedPrefixes rather
than add a second public constructor.
Also records what the gate does NOT cover: live streaming under load, key
rotation on a running pair, and docker-env2 (keyed but neither redeployed nor
gated).
Phase 0 of the ClusterClient→gRPC migration
(docs/plans/2026-07-22-clusterclient-to-grpc-plan.md). Standalone hardening: it
closes a gap that exists today and is a precondition for moving command/control
onto gRPC in later phases.
T0.1 — delete the ManagementActor ClusterClientReceptionist registration.
It was built for an out-of-cluster CLI that was never written: the shipped CLI
speaks HTTP Basic to /management, which asks the actor in-process through
ManagementActorHolder. Nothing in the repo ever sent to /user/management. The
actor still runs there; only the cross-boundary advertisement is gone. Six
documents claimed the CLI used ClusterClient — including the CLI's own README
"Architecture Notes" — and are corrected here rather than left to rot.
T0.2 — record, do not port, the dead integration-routing path.
IntegrationCallRequest is unwired at BOTH ends: RouteIntegrationCallAsync has
zero callers anywhere, and RegisterLocalHandler(Integration, …) appears only in
a test, so production always answers "Integration handler not available". It is
excluded from the gRPC contract (28 of 29 commands migrate) rather than
enshrined on an additive-only wire format, and deleting it during a
transport migration would mix a behavioural change into a change whose whole
value is that behaviour is identical. See
docs/known-issues/2026-07-22-integration-call-routing-is-dead-code.md.
T0.3 — preshared-key authentication on SiteStreamService.
The service shipped with no auth at all: plaintext h2c, no interceptor, so
anything that could reach a site node's :8083 could open a live data stream or
read audit rows back via PullAuditEvents/PullSiteCalls. ControlPlaneAuthInterceptor
now gates /sitestream.SiteStreamService/ — modeled on LocalDbSyncAuthInterceptor
(constant-time compare, fail-closed, PermissionDenied) but gating a SET of
service prefixes so phases 1A/1B add services rather than interceptors. LocalDb
sync keeps its own separate key: it authenticates the pair partner, not central,
and collapsing the two would make a site's central-facing key also admit writes
into its database.
Keys are per site (SB-GRPC-PSK-<siteId>), never fleet-wide, so a compromised
site yields only its own. Central attaches them through ControlPlaneCredentials,
which binds CallCredentials to the channel — covering unary and streaming
uniformly, and letting the key resolve asynchronously, which a client
interceptor could not do without blocking. All three central→site channel
creation sites go through it (SiteStreamGrpcClient and both audit pull invokers);
the pull invokers' channel caches are re-keyed by (site, endpoint) because
credentials are per-site and bound to the channel.
Two decisions beyond the plan:
* StartupValidator now requires GrpcPsk on Site nodes. The plan specified only
the runtime gate, but fail-closed with no boot check produces a node that
joins, answers heartbeats and reports healthy while refusing every stream,
audit pull and telemetry ingest — silent and total. Same reasoning as the
existing inbound API-key pepper rule.
* Added Communication:SitePsks as a central-side key map. The plan assumed
central would read the store, seeded via a dev KEK; the docker rig
deliberately boots with no master key, so store-only resolution would leave
it unable to dial its own sites. The store stays primary — it is the only
source that can serve a site added at runtime — with the map covering
key-less hosts and one-off pins. Neither source falling back to
"unauthenticated" is the invariant.
T0.4 — dev keys on both rigs and tests.
34 tests. The seven that matter most exercise a real in-process gRPC stack over
TestServer: the unit tests on either side of the wire would both stay green if
the halves disagreed, and gRPC refuses call credentials on a plaintext channel
by default — the UnsafeUseInsecureChannelCallCredentials opt-in is only provable
by making a real call. They confirm correct key passes on unary AND streaming,
wrong key and no-credentials both get PermissionDenied, and an unresolvable key
fails the call with nothing reaching the service.
OPERATIONAL: a site node upgraded to this build without a key will not boot.
That includes the gitignored deploy/wonder-app-vd03/ overlay.
Joseph Doherty