Closes Stream C per docs/v2/implementation/phase-6-1-resilience-and-observability.md.
Core.Observability (new namespace):
- DriverHealthReport — pure-function aggregation over DriverHealthSnapshot list.
Empty fleet = Healthy. Any Faulted = Faulted. Any Unknown/Initializing (no
Faulted) = NotReady. Any Degraded or Reconnecting (no Faulted, no NotReady)
= Degraded. Else Healthy. HttpStatus(verdict) maps to the Stream C.1 state
matrix: Healthy/Degraded → 200, NotReady/Faulted → 503.
- LogContextEnricher — Serilog LogContext wrapper. Push(id, type, capability,
correlationId) returns an IDisposable scope; inner log calls carry
DriverInstanceId / DriverType / CapabilityName / CorrelationId structured
properties automatically. NewCorrelationId = 12-hex-char GUID slice for
cases where no OPC UA RequestHeader.RequestHandle is in flight.
CapabilityInvoker — now threads LogContextEnricher around every ExecuteAsync /
ExecuteWriteAsync call site. OtOpcUaServer passes driver.DriverType through
so logs correlate to the driver type too. Every capability call emits
structured fields per the Stream C.4 compliance check.
Server.Observability:
- HealthEndpointsHost — standalone HttpListener on http://localhost:4841/
(loopback avoids Windows URL-ACL elevation; remote probing via reverse
proxy or explicit netsh urlacl grant). Routes:
/healthz → 200 when (configDbReachable OR usingStaleConfig); 503 otherwise.
Body: status, uptimeSeconds, configDbReachable, usingStaleConfig.
/readyz → DriverHealthReport.Aggregate + HttpStatus mapping.
Body: verdict, drivers[], degradedDrivers[], uptimeSeconds.
anything else → 404.
Disposal cooperative with the HttpListener shutdown.
- OpcUaApplicationHost starts the health host after the OPC UA server comes up
and disposes it on shutdown. New OpcUaServerOptions knobs:
HealthEndpointsEnabled (default true), HealthEndpointsPrefix (default
http://localhost:4841/).
Program.cs:
- Serilog pipeline adds Enrich.FromLogContext + opt-in JSON file sink via
`Serilog:WriteJson = true` appsetting. Uses Serilog.Formatting.Compact's
CompactJsonFormatter (one JSON object per line — SIEMs like Splunk,
Datadog, Graylog ingest without a regex parser).
Server.Tests:
- Existing 3 OpcUaApplicationHost integration tests now set
HealthEndpointsEnabled=false to avoid port :4841 collisions under parallel
execution.
- New HealthEndpointsHostTests (9): /healthz healthy empty fleet; stale-config
returns 200 with flag; unreachable+no-cache returns 503; /readyz empty/
Healthy/Faulted/Degraded/Initializing drivers return correct status and
bodies; unknown path → 404. Uses ephemeral ports via Interlocked counter.
Core.Tests:
- DriverHealthReportTests (8): empty fleet, all-healthy, any-Faulted trumps,
any-NotReady without Faulted, Degraded without Faulted/NotReady, HttpStatus
per-verdict theory.
- LogContextEnricherTests (8): all 4 properties attach; scope disposes cleanly;
NewCorrelationId shape; null/whitespace driverInstanceId throws.
- CapabilityInvokerEnrichmentTests (2): inner logs carry structured
properties; no context leak outside the call site.
Full solution dotnet test: 1016 passing (baseline 906, +110 for Phase 6.1 so
far across Streams A+B+C). Pre-existing Client.CLI Subscribe flake unchanged.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
IDriver.DriverInstanceId is declared as string in Core.Abstractions; keeping
the pipeline key as Guid meant every call site would need .ToString() / Guid.Parse
at the boundary. Switching the Resilience types to string removes that friction
and lets OtOpcUaServer pass driver.DriverInstanceId directly to the builder in
the upcoming server-dispatch wiring PR.
- DriverResiliencePipelineBuilder.GetOrCreate + Invalidate + PipelineKey
- CapabilityInvoker.ctor + _driverInstanceId field
Tests: all 48 Core.Tests still pass. The Invalidate test's keepId / dropId now
use distinct "drv-keep" / "drv-drop" literals (previously both were distinct
Guid.NewGuid() values, which the sed-driven refactor had collapsed to the same
literal — caught pre-commit).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
One invoker per (DriverInstance, IDriver) pair; calls ExecuteAsync(capability,
host, callSite) and the invoker resolves the correct pipeline from the shared
DriverResiliencePipelineBuilder. The options accessor is a Func so Admin-edit
+ pipeline-invalidate takes effect without restarting the invoker or the
driver host.
ExecuteWriteAsync(isIdempotent) is the explicit write-safety surface:
- isIdempotent=false routes through a side pipeline with RetryCount=0 regardless
of what the caller configured. The cache key carries a "::non-idempotent"
suffix so it never collides with the retry-enabled write pipeline.
- isIdempotent=true routes through the normal Write pipeline. If the user has
configured Write retries (opt-in), the idempotent tag gets them; otherwise
default-0 still wins.
The server dispatch layer (next PR) reads WriteIdempotentAttribute on each tag
definition once at driver-init time and feeds the boolean into ExecuteWriteAsync.
Tests (6 new):
- Read retries on transient failure; returns value from call site.
- Write non-idempotent does NOT retry even when policy has 3 retries configured
(the explicit decision-#44 guard at the dispatch surface).
- Write idempotent retries when policy allows.
- Write with default tier-A policy (RetryCount=0) never retries regardless of
idempotency flag.
- Different hosts get independent pipelines.
Core.Tests now 44 passing (was 38). Invoker doc-refs completed (the XML comment
on WriteIdempotentAttribute no longer references a non-existent type).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
