feat: harden tidal-server for production (Weeks 1–3)
Week 1 — deployment prerequisites:
- Add TIDAL_API_KEY Bearer auth middleware (constant-time comparison)
- Handle SIGTERM alongside ctrl-c for graceful shutdown
- Remove test-utils feature from production tidal-server binary
- Fix standalone Dockerfile; add cluster Dockerfile and docker-compose
- Extract MultiRegionState into state.rs with per-region TidalDb map
Week 2 — operational middleware and observability:
- Add body limit (2MB), request timeout (30s), concurrency limit (100)
- Add SetRequestIdLayer + PropagateRequestIdLayer (x-request-id header)
- Add TraceLayer with structured spans including request ID
- Activate Prometheus /metrics endpoint via --metrics flag
- Add monitoring.md, recovery.md, prometheus-alerts.yaml, grafana-dashboard.json
Week 3 — query latency histograms and middleware integration tests:
- Add QUERY_LATENCY_BOUNDS (100µs–10s) histogram to tidal library
- Instrument retrieve() and search() with tidaldb_retrieve/search_latency_us
- Fix: search() latency now recorded on error paths (was skipped via ?)
- Lib+bin split in tidal-server enabling integration tests
- Add 8 middleware integration tests (auth, body limit, request ID)
- Add 2 Prometheus alert rules and 2 Grafana latency panels
Post-review fixes:
- Fix SIGTERM handler compilation on non-Unix targets (#[cfg(unix)] guard)
- Exempt /health from TimeoutLayer + ConcurrencyLimitLayer (prevents false liveness failures under load)
- Case-insensitive Bearer scheme matching per RFC 7235 §2.1
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