79 lines
2.2 KiB
Python
79 lines
2.2 KiB
Python
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"""HTTP middlewares for the PolyWeather FastAPI application."""
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import hashlib
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import time
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from fastapi import Request
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from fastapi.responses import Response
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from src.utils.metrics import counter_inc, histogram_observe
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async def metrics_middleware(request: Request, call_next):
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started = time.perf_counter()
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try:
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response = await call_next(request)
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except Exception:
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duration_ms = (time.perf_counter() - started) * 1000.0
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counter_inc(
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"polyweather_http_requests_total",
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method=request.method,
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path=request.url.path,
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status="500",
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)
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histogram_observe(
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"polyweather_http_request_duration_ms",
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duration_ms,
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method=request.method,
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path=request.url.path,
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status="500",
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)
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raise
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duration_ms = (time.perf_counter() - started) * 1000.0
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status_code = str(response.status_code)
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counter_inc(
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"polyweather_http_requests_total",
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method=request.method,
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path=request.url.path,
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status=status_code,
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)
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histogram_observe(
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"polyweather_http_request_duration_ms",
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duration_ms,
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method=request.method,
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path=request.url.path,
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status=status_code,
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)
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return response
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async def etag_middleware(request: Request, call_next):
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"""Add ETag to GET /api/* responses; return 304 on If-None-Match hit."""
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response = await call_next(request)
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if request.method != "GET" or response.status_code != 200:
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return response
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path = request.url.path
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if not path.startswith("/api/") or path.endswith("/stream"):
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return response
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body = getattr(response, "body", None) or b""
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if not body:
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return response
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try:
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etag = hashlib.md5(body).hexdigest()
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except Exception:
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return response
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etag_value = f'"{etag}"'
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if_none_match = request.headers.get("If-None-Match", "")
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if if_none_match == etag_value:
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return Response(status_code=304, headers={"ETag": etag_value})
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response.headers["ETag"] = etag_value
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response.headers["Cache-Control"] = "private, max-age=30"
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return response
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