JiriUhlir
84 lines
2.8 KiB
Python
84 lines
2.8 KiB
Python
"""Domain exceptions and FastAPI exception handlers.
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All errors are surfaced as JSON (never swallowed). Upstream failures preserve
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the upstream status code and body so callers can diagnose problems.
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"""
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from __future__ import annotations
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from typing import Any
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from fastapi import FastAPI, Request
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from fastapi.responses import JSONResponse
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from .logging_config import get_logger
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logger = get_logger(__name__)
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class MissingCredentialsError(Exception):
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"""A required credential header was not supplied."""
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def __init__(self, message: str) -> None:
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super().__init__(message)
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self.message = message
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class UpstreamError(Exception):
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"""The upstream API (Google / Sklik) returned an error or was unreachable.
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``status`` is the HTTP status to return to the caller. ``upstream_status``
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and ``body`` carry the upstream detail when available.
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"""
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def __init__(
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self,
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message: str,
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*,
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status: int = 502,
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upstream_status: int | None = None,
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body: Any = None,
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) -> None:
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super().__init__(message)
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self.message = message
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self.status = status
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self.upstream_status = upstream_status
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self.body = body
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def _problem(status: int, title: str, **extra: Any) -> JSONResponse:
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payload: dict[str, Any] = {"error": title, "status": status}
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payload.update({k: v for k, v in extra.items() if v is not None})
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return JSONResponse(status_code=status, content=payload)
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def register_exception_handlers(app: FastAPI) -> None:
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@app.exception_handler(MissingCredentialsError)
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async def _missing_credentials(request: Request, exc: MissingCredentialsError):
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# Not an error worth a stack trace, but we still log it so missing-header
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# problems are diagnosable. The credential VALUE is never logged.
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logger.warning("Missing credentials for %s: %s", request.url.path, exc.message)
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return _problem(401, "missing_credentials", detail=exc.message)
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@app.exception_handler(UpstreamError)
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async def _upstream_error(request: Request, exc: UpstreamError):
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logger.error(
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"Upstream error on %s: %s (upstream_status=%s)",
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request.url.path,
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exc.message,
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exc.upstream_status,
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)
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return _problem(
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exc.status,
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"upstream_error",
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detail=exc.message,
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upstream_status=exc.upstream_status,
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upstream_body=exc.body,
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)
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@app.exception_handler(Exception)
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async def _unhandled(request: Request, exc: Exception):
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# Last-resort handler: never leak a stack trace to the client, but always
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# log it server-side so nothing fails silently.
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logger.exception("Unhandled error on %s", request.url.path)
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return _problem(500, "internal_error", detail=str(exc))
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