system-prompts-and-models-of-ai-tools/dealix/api/middleware.py

"""FastAPI middleware — request ID, structured logging, timing."""

from __future__ import annotations

import time
import uuid
from collections.abc import Awaitable, Callable

import structlog
from starlette.middleware.base import BaseHTTPMiddleware
from starlette.requests import Request
from starlette.responses import Response

from core.logging import get_logger

logger = get_logger(__name__)


class RequestIDMiddleware(BaseHTTPMiddleware):
    """Attach a unique request ID to each request and bind it to logs."""

    async def dispatch(
        self,
        request: Request,
        call_next: Callable[[Request], Awaitable[Response]],
    ) -> Response:
        request_id = request.headers.get("X-Request-ID") or uuid.uuid4().hex[:12]
        structlog.contextvars.clear_contextvars()
        structlog.contextvars.bind_contextvars(
            request_id=request_id,
            method=request.method,
            path=request.url.path,
        )

        start = time.perf_counter()
        try:
            response = await call_next(request)
        except Exception as e:
            logger.exception("request_unhandled_error", error=str(e))
            raise
        duration_ms = (time.perf_counter() - start) * 1000

        response.headers["X-Request-ID"] = request_id
        logger.info(
            "request_completed",
            status_code=response.status_code,
            duration_ms=round(duration_ms, 2),
        )
        return response