Introduce loguru logging with full stdlib and click interception

Author: jgbustos

ml_rest_api/app.py

@@ -3,9 +3,9 @@
 import os
 import warnings
 from logging import Logger, getLogger
-import logging.config
 from flask import Flask
 from flask_wtf import CSRFProtect  # pylint: disable=unused-import  # type: ignore
+from ml_rest_api.logging_setup import setup_logging
 from ml_rest_api.settings import get_value
 from ml_rest_api.ml_trained_model.wrapper import trained_model_wrapper
 from ml_rest_api.api.restx import blueprint
@@ -65,9 +65,7 @@ def main() -> None:
 
 
 APP = Flask(__name__)
-logging.config.fileConfig(
-    os.path.normpath(os.path.join(os.path.dirname(__file__), "../logging.conf"))
-)
+setup_logging()
 log: Logger = getLogger(__name__)
 initialize_app(APP)
 

ml_rest_api/logging_setup.py

@@ -0,0 +1,87 @@
+"""Loguru-based logging setup that intercepts all stdlib logging."""
+
+import inspect
+import logging
+import sys
+from typing import Any
+import click
+from loguru import logger
+
+
+class InterceptHandler(logging.Handler):
+    """Intercepts stdlib logging calls and redirects them to loguru."""
+
+    def emit(self, record: logging.LogRecord) -> None:
+        try:
+            level: str | int = logger.level(record.levelname).name
+        except ValueError:
+            level = record.levelno
+
+        frame, depth = inspect.currentframe(), 0
+        for _ in range(6):
+            if frame is not None:
+                frame = frame.f_back
+                depth += 1
+        while frame and frame.f_code.co_filename == logging.__file__:
+            frame = frame.f_back  # type: ignore[assignment]
+            depth += 1
+
+        for line in record.getMessage().splitlines():
+            logger.opt(depth=depth, exception=record.exc_info).log(level, line)
+
+
+def setup_logging(level: str = "DEBUG") -> None:
+    """Configure loguru and intercept all stdlib logging."""
+    logger.remove()
+    logger.add(
+        sys.stdout,
+        level=level,
+        format=(
+            "<green>{time:YYYY-MM-DD HH:mm:ss}</green> | "
+            "<level>{level: <8}</level> | "
+            "<cyan>{name}</cyan>:<cyan>{line}</cyan> - "
+            "<level>{message}</level>"
+        ),
+        colorize=True,
+    )
+    # Replace root logger handler — all child loggers propagate here by default
+    logging.basicConfig(handlers=[InterceptHandler()], level=0, force=True)
+    # Clear handlers on existing child loggers and ensure they propagate to root
+    for name in logging.root.manager.loggerDict:  # pylint: disable=no-member
+        existing = logging.getLogger(name)
+        existing.handlers.clear()
+        existing.propagate = True
+    # Intercept click.echo (used by Flask/Werkzeug for * startup lines)
+    _original_echo = click.echo
+
+    def _echo_to_loguru(
+        message: Any = None,
+        file: Any = None,
+        nl: bool = True,
+        err: bool = False,
+        color: Any = None,
+    ) -> None:
+        if message is not None and file is None and not err:
+            logger.opt(depth=1).info(str(message))
+        else:
+            _original_echo(message, file=file, nl=nl, err=err, color=color)
+
+    click.echo = _echo_to_loguru  # type: ignore[assignment]
+
+    # Also intercept click.secho (used by Werkzeug for * Running on lines)
+    _original_secho = click.secho
+
+    def _secho_to_loguru(
+        message: Any = None,
+        file: Any = None,
+        nl: bool = True,
+        err: bool = False,
+        color: Any = None,
+        **styles: Any,
+    ) -> None:
+        if message is not None and file is None and not err:
+            logger.opt(depth=1).info(str(message))
+        else:
+            _original_secho(message, file=file, nl=nl, err=err, color=color, **styles)
+
+    click.secho = _secho_to_loguru  # type: ignore[assignment]

requirements.txt

@@ -1,4 +1,5 @@
 setuptools>=82.0.0
+loguru==0.7.3
 Flask==3.1.3
 flask-restx==1.3.2
 Flask-WTF==1.2.2