Distributed HTTP Telemetry

[patrickleet]

Summary

• add bounded HTTP server request counter and duration metrics for Distributed-owned routers
• add shared Axum HTTP telemetry middleware with optional OTEL SERVER spans parented from incoming W3C trace context
• cover command HTTP, metrics-only, and Knative CloudEvents routers plus docs for request-vs-dispatch boundaries and privacy rules

Acceptance Criteria Addressed

• GET /health, GET /metrics, command HTTP success/unknown/pre-dispatch rejection, and Knative CloudEvents ingress record HTTP request metrics with route templates only
• Prometheus exposition includes the new HTTP metric families and is covered by promtool-compatible integration test output
• metric labels are bounded to service/method/route/status_code and existing framework labels; tests assert raw paths, queries, trace IDs, user IDs, aggregate IDs, headers, and payload data are not emitted
• existing dispatch metrics remain intact, including unknown commands bucketed as message="unknown"
• http, http+metrics, http+otel, and http+metrics+otel feature combinations compile
• OTLP integration test covers HTTP span parenting and dispatch span child relationship when collector env is available
• docs updated in metrics, observability, transports, and README

Local Validation

• cargo check --no-default-features --features http
• cargo check --no-default-features --features http,metrics
• cargo check --no-default-features --features http,otel
• cargo check --no-default-features --features http,metrics,otel
• cargo clippy --all-targets --no-default-features --features http,metrics,otel -- -D warnings
• cargo test --no-default-features --features http,metrics,otel
• cargo test --lib --no-default-features --features http,metrics
• cargo test --test microsvc --no-default-features --features http,metrics
• cargo test --test knative_cloudevents --no-default-features --features http,metrics
• cargo test --test metrics_exposition --no-default-features --features http,metrics
• cargo test --test otel_export --no-default-features --features http,otel
• git diff --check

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Review details

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: ae790333-95ac-4a4d-b3bc-42119e164410

📥 Commits

Reviewing files that changed from the base of the PR and between 84a72f1 and 82f5a82.

📒 Files selected for processing (15)

• README.md
• docs/metrics.md
• docs/observability.md
• docs/transports.md
• src/http_telemetry.rs
• src/lib.rs
• src/metrics.rs
• src/microsvc/http.rs
• src/microsvc/knative_ingress.rs
• src/telemetry.rs
• src/trace_context.rs
• tests/knative_cloudevents/main.rs
• tests/metrics_exposition/main.rs
• tests/microsvc/transport_http.rs
• tests/otel_export/main.rs

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch tasks--distributed-http-telemetry-1

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