Python および FastAPI 構造化ロギング

import asyncio
import time
import uuid

# app and the initialized TelemetryAsync client already exist.
@app.middleware("http")
async def record_request(request, call_next):
    started_at = time.perf_counter()
    request_id = uuid.uuid4().hex
    response = await call_next(request)
    route = request.scope.get("route")
    latency_ms = round((time.perf_counter() - started_at) * 1000)

    try:
        await asyncio.wait_for(telemetry.log("fastapi_response_observed", {
            "route_template": getattr(route, "path", "unmatched"),
            "method": request.method,
            "status_code": response.status_code,
            "status": "response_observed",
            "latency_ms": latency_ms,
            "request_id": request_id,
        }), timeout=1.0)
    except Exception:
        # Best effort: connect this to your existing safe diagnostics.
        pass
    return response