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rippled/OpenTelemetryPlan/Phase2_taskList.md
2026-03-09 19:24:21 +00:00

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# Phase 2: RPC Tracing Completion Task List
> **Goal**: Complete full RPC tracing coverage with W3C Trace Context propagation, unit tests, and performance validation. Build on the POC foundation to achieve production-quality RPC observability.
>
> **Scope**: W3C header extraction, TraceContext propagation utilities, unit tests for core telemetry, integration tests for RPC tracing, and performance benchmarks.
>
> **Branch**: `pratik/otel-phase2-rpc-tracing` (from `pratik/OpenTelemetry_and_DistributedTracing_planning`)
### Related Plan Documents
| Document | Relevance |
| ------------------------------------------------------------ | ------------------------------------------------------------- |
| [04-code-samples.md](./04-code-samples.md) | TraceContextPropagator (§4.4.2), RPC instrumentation (§4.5.3) |
| [02-design-decisions.md](./02-design-decisions.md) | W3C Trace Context (§2.5), span attributes (§2.4.2) |
| [06-implementation-phases.md](./06-implementation-phases.md) | Phase 2 tasks (§6.3), definition of done (§6.11.2) |
---
## Task 2.1: Implement W3C Trace Context HTTP Header Extraction
**Objective**: Extract `traceparent` and `tracestate` headers from incoming HTTP RPC requests so external callers can propagate their trace context into rippled.
**What to do**:
- Create `include/xrpl/telemetry/TraceContextPropagator.h`:
- `extractFromHeaders(headerGetter)` - extract W3C traceparent/tracestate from HTTP headers
- `injectToHeaders(ctx, headerSetter)` - inject trace context into response headers
- Use OTel's `TextMapPropagator` with `W3CTraceContextPropagator` for standards compliance
- Only compiled when `XRPL_ENABLE_TELEMETRY` is defined
- Create `src/libxrpl/telemetry/TraceContextPropagator.cpp`:
- Implement a simple `TextMapCarrier` adapter for HTTP headers
- Use `opentelemetry::context::propagation::GlobalTextMapPropagator` for extraction/injection
- Register the W3C propagator in `TelemetryImpl::start()`
- Modify `src/xrpld/rpc/detail/ServerHandler.cpp`:
- In the HTTP request handler, extract parent context from headers before creating span
- Pass extracted context to `startSpan()` as parent
- Inject trace context into response headers
**Key new files**:
- `include/xrpl/telemetry/TraceContextPropagator.h`
- `src/libxrpl/telemetry/TraceContextPropagator.cpp`
**Key modified files**:
- `src/xrpld/rpc/detail/ServerHandler.cpp`
- `src/libxrpl/telemetry/Telemetry.cpp` (register W3C propagator)
**Reference**:
- [04-code-samples.md §4.4.2](./04-code-samples.md) — TraceContextPropagator with extractFromHeaders/injectToHeaders
- [02-design-decisions.md §2.5](./02-design-decisions.md) — W3C Trace Context propagation design
---
## Task 2.2: Add XRPL_TRACE_PEER Macro
**Objective**: Add the missing peer-tracing macro for future Phase 3 use and ensure macro completeness.
**What to do**:
- Edit `src/xrpld/telemetry/TracingInstrumentation.h`:
- Add `XRPL_TRACE_PEER(_tel_obj_, _span_name_)` macro that checks `shouldTracePeer()`
- Add `XRPL_TRACE_LEDGER(_tel_obj_, _span_name_)` macro (for future ledger tracing)
- Ensure disabled variants expand to `((void)0)`
**Key modified file**:
- `src/xrpld/telemetry/TracingInstrumentation.h`
---
## Task 2.3: Add shouldTraceLedger() to Telemetry Interface
**Objective**: The `Setup` struct has a `traceLedger` field but there's no corresponding virtual method. Add it for interface completeness.
**What to do**:
- Edit `include/xrpl/telemetry/Telemetry.h`:
- Add `virtual bool shouldTraceLedger() const = 0;`
- Update all implementations:
- `src/libxrpl/telemetry/Telemetry.cpp` (TelemetryImpl, NullTelemetryOtel)
- `src/libxrpl/telemetry/NullTelemetry.cpp` (NullTelemetry)
**Key modified files**:
- `include/xrpl/telemetry/Telemetry.h`
- `src/libxrpl/telemetry/Telemetry.cpp`
- `src/libxrpl/telemetry/NullTelemetry.cpp`
---
## Task 2.4: Unit Tests for Core Telemetry Infrastructure
**Objective**: Add unit tests for the core telemetry abstractions to validate correctness and catch regressions.
**What to do**:
- Create `src/test/telemetry/Telemetry_test.cpp`:
- Test NullTelemetry: verify all methods return expected no-op values
- Test Setup defaults: verify all Setup fields have correct defaults
- Test setup_Telemetry config parser: verify parsing of [telemetry] section
- Test enabled/disabled factory paths
- Test shouldTrace\* methods respect config flags
- Create `src/test/telemetry/SpanGuard_test.cpp`:
- Test SpanGuard RAII lifecycle (span ends on destruction)
- Test move constructor works correctly
- Test setAttribute, setOk, setStatus, addEvent, recordException
- Test context() returns valid context
- Add test files to CMake build
**Key new files**:
- `src/test/telemetry/Telemetry_test.cpp`
- `src/test/telemetry/SpanGuard_test.cpp`
**Reference**:
- [06-implementation-phases.md §6.11.1](./06-implementation-phases.md) — Phase 1 exit criteria (unit tests passing)
---
## Task 2.5: Enhance RPC Span Attributes
**Objective**: Add additional attributes to RPC spans per the semantic conventions defined in the plan.
**What to do**:
- Edit `src/xrpld/rpc/detail/ServerHandler.cpp`:
- Add `http.method` attribute for HTTP requests
- Add `http.status_code` attribute for responses
- Add `net.peer.ip` attribute for client IP (if available)
- Edit `src/xrpld/rpc/detail/RPCHandler.cpp`:
- Add `xrpl.rpc.duration_ms` attribute on completion
- Add error message attribute on failure: `xrpl.rpc.error_message`
**Key modified files**:
- `src/xrpld/rpc/detail/ServerHandler.cpp`
- `src/xrpld/rpc/detail/RPCHandler.cpp`
**Reference**:
- [02-design-decisions.md §2.4.2](./02-design-decisions.md) — RPC attribute schema
---
## Task 2.6: Build Verification and Performance Baseline
**Objective**: Verify the build succeeds with and without telemetry, and establish a performance baseline.
**What to do**:
1. Build with `telemetry=ON` and verify no compilation errors
2. Build with `telemetry=OFF` and verify no regressions
3. Run existing unit tests to verify no breakage
4. Document any build issues in lessons.md
**Verification Checklist**:
- [ ] `conan install . --build=missing -o telemetry=True` succeeds
- [ ] `cmake --preset default -Dtelemetry=ON` configures correctly
- [ ] Build succeeds with telemetry ON
- [ ] Build succeeds with telemetry OFF
- [ ] Existing tests pass with telemetry ON
- [ ] Existing tests pass with telemetry OFF
---
## Summary
| Task | Description | New Files | Modified Files | Depends On |
| ---- | ------------------------------------------- | --------- | -------------- | ---------- |
| 2.1 | W3C Trace Context header extraction | 2 | 2 | POC |
| 2.2 | Add XRPL_TRACE_PEER/LEDGER macros | 0 | 1 | POC |
| 2.3 | Add shouldTraceLedger() interface method | 0 | 3 | POC |
| 2.4 | Unit tests for core telemetry | 2 | 1 | POC |
| 2.5 | Enhanced RPC span attributes | 0 | 2 | POC |
| 2.6 | Build verification and performance baseline | 0 | 0 | 2.1-2.5 |
**Parallel work**: Tasks 2.1, 2.2, 2.3 can run in parallel. Task 2.4 depends on 2.3. Task 2.5 can run in parallel with 2.4. Task 2.6 depends on all others.