Add some typing and support existing handlers

modellogger/log_config.py

@@ -1,7 +1,7 @@
 import logging
 import sys
 import time
-from logging import INFO
+from typing import Any, Dict, Optional
 
 
 class DefaultFormatter(logging.Formatter):
@@ -15,15 +15,15 @@ class DefaultFormatter(logging.Formatter):
         "RESET": "\x1b[0m",
     }
 
-    def __init__(self, app_name=".", include_colors=True):
+    def __init__(self, app_name: str = ".", include_colors: bool = True):
         super().__init__()
         self.app_name = app_name
         self.include_colors = include_colors
         self.base_format = (
             "%(asctime)s - {app_name} - %(name)s - %(levelname)s - %(message)s"
         )
 
-    def format(self, record):
+    def format(self, record: logging.LogRecord) -> str:
         date_format = "%Y-%m-%dT%H:%M:%SZ"
         log_fmt = self.base_format.format(app_name=self.app_name)
 
@@ -36,12 +36,24 @@ def format(self, record):
         return formatter.format(record)
 
 
-def configure_logging(app_name=".", level=INFO, log_file=None):
+def configure_logging(
+    app_name: str = ".",
+    level: int = logging.INFO,
+    log_file: Optional[str] = None,
+) -> None:
+    """Configures the root logger. Preserves existing handlers (if any).
+
+    NOTE: if you call this function multiple times, you may end up with
+    duplicate log messages, since each call adds new handlers to the root logger.
+
+    Args:
+        app_name: Name of the application to include in log messages.
+        level: Logging level to set.
+        log_file: If provided, log to this file instead of stderr.
+    """
     logger = logging.getLogger()
     logger.setLevel(level)
 
-    logger.handlers.clear()
-
     if log_file:
         file_handler = logging.FileHandler(log_file)
         file_handler.setFormatter(DefaultFormatter(app_name, include_colors=False))
@@ -52,13 +64,15 @@ def configure_logging(app_name=".", level=INFO, log_file=None):
         logger.addHandler(console_handler)
 
 
-def get_logger(name):
+def get_logger(name: str) -> logging.Logger:
     logger = logging.getLogger(name)
     return logger
 
 
-def get_config_dict(app_name=".", log_file=None):
-    config = {
+def get_config_dict(
+    app_name: str = ".", log_file: Optional[str] = None
+) -> Dict[str, Any]:
+    config: Dict[str, Any] = {
         "version": 1,
         "disable_existing_loggers": False,
         "formatters": {

tests/test_log_config.py

@@ -50,7 +50,7 @@ def test_configure_logging():
     root_logger = logging.getLogger()
     assert root_logger.name == "root"
     assert root_logger.level == logging.INFO
-    assert isinstance(root_logger.handlers[0], logging.StreamHandler)
+    assert isinstance(root_logger.handlers[-1], logging.StreamHandler)
 
 
 def test_configure_logging_with_file(tmp_path):
@@ -60,7 +60,7 @@ def test_configure_logging_with_file(tmp_path):
     root_logger = logging.getLogger()
     assert root_logger.name == "root"
     assert root_logger.level == logging.INFO
-    assert isinstance(root_logger.handlers[0], logging.FileHandler)
+    assert isinstance(root_logger.handlers[-1], logging.FileHandler)
 
 
 def test_get_logger_basic():