FastAPIのUvicornログをLoguruで統一する方法

背景

FastAPIプロジェクトにLoguru導入したが、Uvicornのログが標準のまま。
UvicornのログもLoguruのログ形式に寄せたい。

INFO:     Started server process [50656]
INFO:     Waiting for application startup.
INFO:     Application startup complete.
2024-05-10 23:11:23.479 | ERROR    | backend.interface.api.v1.messages:create_user_message:22 - Failed to create user message
INFO:     127.0.0.1:61688 - "POST /v1/messages HTTP/1.1" 500 Internal Server Error

やったこと

1. UvicornログをLoguruの形式に変換

   import logging
   from loguru import logger
   
   
   class InterceptHandler(logging.Handler):
       def emit(self, record):
           # 既存のログレコードの属性を使用してLoguruでログを出力
           logger_opt = logger.opt(depth=6, exception=record.exc_info)
           logger_opt.log(record.levelname, record.getMessage())
   
   
   def setup_logger():
       # uvicornログをInterceptHandlerにリダイレクト
       for _logger in ("uvicorn", "uvicorn.error", "uvicorn.access"):
           logging_logger = logging.getLogger(_logger)
           logging_logger.handlers = [InterceptHandler()]
           logging_logger.propagate = False  # ログが２重出力されるのを防止
   

   
   

2. あとはmainで呼び出すだけ

   from fastapi import FastAPI
   from backend.logging.config import setup_logger
   
   setup_logger()
   app = FastAPI()
   

結果

Loguruのログに切り替わったことを確認

2024-05-10 23:22:41.864 | INFO     | uvicorn.server:_serve:82 - Started server process [50805]
2024-05-10 23:22:41.864 | INFO     | uvicorn.lifespan.on:startup:48 - Waiting for application startup.
2024-05-10 23:22:41.865 | INFO     | uvicorn.lifespan.on:startup:62 - Application startup complete.
2024-05-10 23:24:26.892 | ERROR    | backend.interface.api.v1.messages:create_user_message:22 - Failed to create user message
2024-05-10 23:24:26.892 | INFO     | uvicorn.protocols.http.httptools_impl:send:481 - 127.0.0.1:61785 - "POST /v1/messages HTTP/1.1" 500