Loguru Integration

Loguru is a modern logging library that simplifies logging configuration and provides better features out of the box.

Why Loguru?

Compared to Python’s standard logging:

• Simpler Configuration: No more handlers, formatters, or complex setup
• Better Syntax: More intuitive API with method chaining
• Rich Features: Built-in rotation, compression, and filtering
• Exception Handling: Better stack traces and error information

Installation

uv add loguru

loguru’s default logger is fantastic out of the box and can be used simply by importing it:

from loguru import logger

InterceptHandler

To configure uvicorn with loguru, we need to inctercept Uvicorns logs with an InterceptHandler:

class InterceptHandler(logging.Handler):
    def emit(self, record: logging.LogRecord) -> None:
        # Get corresponding Loguru level if it exists
        level: str | int
        try:
            level = logger.level(record.levelname).name
        except ValueError:
            level = record.levelno

        # Find caller from where originated the logged message
        frame, depth = logging.currentframe(), 2
        while frame and frame.f_code.co_filename == logging.__file__:
            frame = frame.f_back
            depth += 1

        logger.opt(depth=depth, exception=record.exc_info).log(
            level, record.getMessage()
        )

Then we can use the handler the same way we did before:

for name in logging.root.manager.loggerDict:
    if name in ("uvicorn"):
        uvicorn_logger = logging.getLogger(name)
        uvicorn_logger.handlers.clear()
        uvicorn_logger.setLevel(logging.INFO)
        uvicorn_logger.addHandler(InterceptHandler())

Testing

Run your application and you’ll see the same consistent output, but now powered by Loguru’s more robust logging system.

The InterceptHandler ensures that all standard logging calls (including those from FastAPI and Uvicorn) are routed through Loguru, giving you unified control over your application’s logging behavior.