388 lines
15 KiB
Python
388 lines
15 KiB
Python
"""Logging integration: tracerite loading and colored access log formatting.
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The access log middleware supplies colored fields (``client``, ``status``,
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``method``, ``host``, ``path``, ``extra``, ``timing``) via ``extra=``. When
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colors are disabled the ANSI escape codes are stripped from the assembled
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output so the same formatting code path produces plain text.
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"""
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from __future__ import annotations
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import io
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import logging
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import re
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import sys
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from contextlib import suppress
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from copy import deepcopy
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from typing import TYPE_CHECKING, Literal
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import tracerite
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from starlette.middleware.errors import ServerErrorMiddleware
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from starlette.responses import HTMLResponse, JSONResponse, PlainTextResponse, Response
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from uvicorn.config import Config
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from uvicorn.lifespan.on import LifespanOn
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if TYPE_CHECKING:
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from typing import Any
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from starlette.requests import Request
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from uvicorn._types import LifespanScope
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from uvicorn.lifespan.on import LifespanSendMessage
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from .accesslog import AccessLogMiddleware
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ANSI_ESCAPE_RE = re.compile(r"\x1b\[[0-9;]*m")
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ACCESS_LOG_FMT = "%(client)s %(status)s %(method)s %(host)s%(path)s %(extra)s%(timing)s"
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ACCESS_LOGGER = "fastapi_vue.access"
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def strip_ansi(text: str) -> str:
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"""Remove ANSI escape codes from text."""
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return ANSI_ESCAPE_RE.sub("", text)
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_LEVEL_EMOJI = {
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logging.DEBUG: "🐛",
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logging.INFO: "🔷",
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logging.WARNING: "❗",
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logging.ERROR: "🛑",
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logging.CRITICAL: "🚨",
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}
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def _level_prefix(record: logging.LogRecord) -> str:
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emoji = _LEVEL_EMOJI.get(record.levelno)
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return f"{emoji} " if emoji else f"{record.levelname}: "
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class Formatter(logging.Formatter):
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"""Formatter for both access records and ordinary log messages.
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Records with the middleware's access fields (``client`` etc.) are
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formatted from those; anything else gets an emoji level prefix
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(``LEVEL: `` fallback for unknown levels) in place of uvicorn's
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``levelprefix``.
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Instantiation always loads tracerite, and with ``access=True`` also
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installs the access-log middleware: ``dictConfig`` builds formatters while
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uvicorn applies ``log_config``, which happens before the app is loaded —
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including in reload/worker subprocesses that re-import the config without
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calling ``fastapi_vue.server.run()`` again. Patching the server error
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middleware here likewise propagates it to those subprocesses.
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"""
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def __init__(
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self,
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fmt: str | None = None,
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datefmt: str | None = None,
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style: Literal["%", "{", "$"] = "%",
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use_colors: bool | None = None, # noqa: FBT001 # mirrors logging.Formatter
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*,
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access: bool = False,
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) -> None:
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"""Load tracerite, optionally install the access log, detect color support."""
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tracerite.load()
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tracerite.load_suppressions(
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extra={"starlette.routing": "until", "fastapi.routing": "until"}
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)
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patch_lifespan_logging()
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patch_server_error_middleware()
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if access:
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install_access_log()
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if use_colors in (True, False):
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self.use_colors = use_colors
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else:
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self.use_colors = sys.stdout.isatty()
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super().__init__(fmt=fmt, datefmt=datefmt, style=style)
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def formatMessage(self, record: logging.LogRecord) -> str: # noqa: N802
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"""Format access records via middleware fields, others with an emoji prefix."""
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if "client" not in record.__dict__:
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return _level_prefix(record) + record.getMessage()
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formatted = super().formatMessage(record)
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if not self.use_colors:
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formatted = strip_ansi(formatted)
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return formatted
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class WebSocketChatterFilter(logging.Filter):
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"""Drop stock uvicorn WebSocket handshake/chatter records.
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Stock uvicorn logs WS handshakes (``'%s - "WebSocket %s" ...'``) and the
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websockets library's "connection open/closed" chatter to ``uvicorn.error``,
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ungated by ``access_log``. Our middleware logs WebSockets itself.
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"""
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_PREFIXES = ('%s - "WebSocket ', "connection open", "connection closed", "connection rejected")
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def filter(self, record: logging.LogRecord) -> bool:
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"""Keep records not matching stock WebSocket chatter prefixes."""
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msg = record.msg
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if not isinstance(msg, str):
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return True
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return not msg.startswith(self._PREFIXES)
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class UvicornQuietFilter(logging.Filter):
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"""Silence uvicorn's routine chatter (startup/shutdown lines, etc.).
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Handler-side, not a logger level: uvicorn's ``configure_logging``
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re-applies ``log_level`` to its loggers after ``dictConfig``, which would
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override a level lifted in the config dict.
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"""
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def filter(self, record: logging.LogRecord) -> bool:
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"""Drop uvicorn records below WARNING."""
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return not (record.name.startswith("uvicorn") and record.levelno < logging.WARNING)
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_installed = False
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def install_access_log() -> None:
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"""Wrap apps loaded by uvicorn with AccessLogMiddleware, once per process.
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The guard is deliberately module-level: reload/worker subprocesses
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re-import this module, resetting it so the patch is re-applied there.
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"""
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global _installed # noqa: PLW0603 # deliberately module-level, see docstring
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if _installed:
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return
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_installed = True
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original_load = Config.load
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def load(self): # noqa: ANN001, ANN202
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original_load(self)
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if not isinstance(self.loaded_app, AccessLogMiddleware):
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self.loaded_app = AccessLogMiddleware(self.loaded_app)
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Config.load = load # type: ignore[method-assign]
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_lifespan_patched = False
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def patch_lifespan_logging() -> None:
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"""Patch uvicorn's LifespanOn to log lifespan failures with exc_info.
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Starlette formats lifespan exceptions into a plain-text ASGI message,
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which uvicorn logs as-is without exc_info, while the exc_info-carrying
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log in ``LifespanOn.main()`` is skipped when a failure message was sent.
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This suppresses the text message and always logs the exception with
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exc_info, so tracerite (or any exc_info-aware handler) renders the
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traceback. Monkeypatches uvicorn internals; written against uvicorn 0.52.
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"""
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global _lifespan_patched # noqa: PLW0603 # once-per-process, resets in subprocesses
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if _lifespan_patched:
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return
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_lifespan_patched = True
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original_send = LifespanOn.send
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async def send(self: LifespanOn, message: LifespanSendMessage) -> None:
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# Drop the pre-formatted traceback text; main() logs the exception itself.
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if message["type"] in ("lifespan.startup.failed", "lifespan.shutdown.failed"):
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message = dict(message) # type: ignore[assignment]
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message.pop("message", None)
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await original_send(self, message)
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async def main(self: LifespanOn) -> None:
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"""Mirror upstream LifespanOn.main, but always log failures with exc_info."""
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try:
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app = self.config.loaded_app
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scope: LifespanScope = {
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"type": "lifespan",
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"asgi": {"version": self.config.asgi_version, "spec_version": "2.0"},
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"state": self.state,
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}
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await app(scope, self.receive, self.send)
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except BaseException:
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self.asgi = None
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self.error_occurred = True
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if self.startup_failed or self.shutdown_failed or self.config.lifespan != "auto":
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phase = "shutdown" if self.shutdown_failed else "startup"
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self.logger.exception("Uncaught exception during application %s", phase)
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else:
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self.logger.info("ASGI 'lifespan' protocol appears unsupported.")
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finally:
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self.startup_event.set()
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self.shutdown_event.set()
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LifespanOn.send = send # type: ignore[method-assign]
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LifespanOn.main = main # type: ignore[method-assign]
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_server_error_patched = False
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DEBUG_INGRESS = """This page is shown for your guidance because the application is \
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running in debug mode and has crashed handling this request."""
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def _generate_html(exc: Exception) -> str:
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return tracerite.html_page(
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exc,
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title="FastAPI debugger",
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heading="500 Server Error",
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ingress=DEBUG_INGRESS,
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)
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def _generate_plain_text(exc: Exception) -> str:
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buffer = io.StringIO()
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tracerite.tty_traceback(exc, file=buffer)
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return buffer.getvalue()
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def _generate_json(exc: Exception) -> dict[str, Any]:
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chain = tracerite.extract_chain(exc)
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return {"detail": "Internal Server Error", "traceback": chain}
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def patch_server_error_middleware() -> None:
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"""Patch Starlette's ServerErrorMiddleware to format debug errors with tracerite.
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Starlette's debug responses use its own static HTML traceback template.
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This replaces ``debug_response`` with tracerite renderers (source
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context, locals, chained exceptions), adds ``accept: application/json``
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handling, and returns a JSON body also for non-debug errors when
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requested. Only apps running with ``debug=True`` produce traceback
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responses. Monkeypatches Starlette internals; written against
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starlette 1.6.
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"""
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global _server_error_patched # noqa: PLW0603 # once-per-process, resets in subprocesses
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if _server_error_patched:
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return
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_server_error_patched = True
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def debug_response(
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self: ServerErrorMiddleware, # noqa: ARG001
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request: Request,
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exc: Exception,
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) -> Response:
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accept = request.headers.get("accept", "")
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if "text/html" in accept:
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return HTMLResponse(_generate_html(exc), status_code=500)
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if "application/json" in accept:
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return JSONResponse(_generate_json(exc), status_code=500)
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return PlainTextResponse(_generate_plain_text(exc), status_code=500)
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def error_response(
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self: ServerErrorMiddleware, # noqa: ARG001
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request: Request,
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exc: Exception, # noqa: ARG001 # signature mirrors Starlette's
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) -> Response:
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if "application/json" in request.headers.get("accept", ""):
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return JSONResponse({"detail": "Internal Server Error"}, status_code=500)
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return PlainTextResponse("Internal Server Error", status_code=500)
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ServerErrorMiddleware.debug_response = debug_response # type: ignore[method-assign]
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ServerErrorMiddleware.error_response = error_response # type: ignore[method-assign]
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def patch_log_config(log_config, *, access_log: bool = True): # noqa: ANN001, ANN201
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"""Patch a uvicorn log_config dict for our logging, best-effort.
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Users presumably base their config on uvicorn's default dict, but any
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shape is tolerated: pieces that do not fit the config's structure are
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silently skipped. Non-dict configs (e.g. an ini file path) pass through
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untouched.
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Always adds an unreferenced NullHandler whose Formatter instantiation
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loads tracerite in every process uvicorn applies the config in, filters
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on the default handler dropping stock uvicorn's WebSocket chatter and
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routine INFO lines, an emoji-level-prefix Formatter in place of
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uvicorn's stock ``default`` formatter (a user-supplied one wins), a root
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logger entry so ``logging.info()`` et al. print through the default
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handler, and a no-prefix ``kanta`` logger entry (likewise). The
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``watchfiles.main`` logger is lifted to WARNING so its INFO "N changes
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detected" line is dropped while the WARNING "Reloading..." line (logged
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to ``uvicorn.error``) still shows; a user-supplied level wins.
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With ``access_log``, additionally rewires the ``access`` formatter to
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our Formatter and attaches its handler to our ``fastapi_vue.access``
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logger. We must not
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attach handlers to ``uvicorn.access``: uvicorn gates its own
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protocol-level access logging on ``uvicorn.access.hasHandlers()``.
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"""
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if not isinstance(log_config, dict):
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return log_config
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config = deepcopy(log_config)
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with suppress(Exception):
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config["formatters"]["fastapi_vue"] = {"()": "fastapi_vue.logging.Formatter"}
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config["handlers"]["fastapi_vue"] = {
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"class": "logging.NullHandler",
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"formatter": "fastapi_vue",
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}
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with suppress(Exception):
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filters = config.setdefault("filters", {})
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filters["ws_chatter"] = {"()": "fastapi_vue.logging.WebSocketChatterFilter"}
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filters["uvicorn_quiet"] = {"()": "fastapi_vue.logging.UvicornQuietFilter"}
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handler_filters = config["handlers"]["default"].setdefault("filters", [])
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for name in ("ws_chatter", "uvicorn_quiet"):
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if name not in handler_filters:
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handler_filters.append(name)
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# Emoji level prefixes for ordinary logs, replacing uvicorn's stock
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# default formatter; a user-supplied default formatter is left alone.
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with suppress(Exception):
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default = config["formatters"]["default"]
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if default.get("()") in (None, "uvicorn.logging.DefaultFormatter"):
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config["formatters"]["default"] = {
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"()": "fastapi_vue.logging.Formatter",
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"fmt": "%(message)s",
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"use_colors": None,
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}
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# uvicorn's default config leaves the root logger handlerless, eating
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# logging.info() et al.; route root through uvicorn's default handler.
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with suppress(Exception):
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root = config.setdefault("root", {})
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root.setdefault("level", "INFO")
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root_handlers = root.setdefault("handlers", [])
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if "default" not in root_handlers:
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root_handlers.append("default")
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# watchfiles logs "N changes detected" to its own logger at INFO; only the
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# WARNING "Reloading..." line (uvicorn.error) should show.
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with suppress(Exception):
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config.setdefault("loggers", {}).setdefault("watchfiles.main", {}).setdefault("level", "WARNING")
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# kanta-style output (diffs, colored headers) prints without prefixes,
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# like our access log. A user-supplied "kanta" logger entry wins.
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with suppress(Exception):
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config["formatters"].setdefault("plain", {"fmt": "%(message)s"})
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config["handlers"].setdefault(
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"plain",
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{
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"class": "logging.StreamHandler",
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"formatter": "plain",
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"stream": "ext://sys.stderr",
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},
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)
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config.setdefault("loggers", {}).setdefault(
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"kanta",
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{"handlers": ["plain"], "level": "INFO", "propagate": False},
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)
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if access_log:
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with suppress(Exception):
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config["formatters"]["access"] = {
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"()": "fastapi_vue.logging.Formatter",
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"fmt": ACCESS_LOG_FMT,
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"use_colors": None,
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"access": True,
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}
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with suppress(Exception):
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if "access" in config["handlers"]:
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config.setdefault("loggers", {})[ACCESS_LOGGER] = {
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"handlers": ["access"],
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"level": "INFO",
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"propagate": False,
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}
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return config
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