fix(scrapy): make logging configuration idempotent (#954)

`initialize_logging` re-wrapped `scrapy.utils.log.configure_logging` on
every call, stacking wrappers when it ran more than once. The
monkey-patch is now installed at most once and reads the current handler
and level from a module-level state dict, so repeated initialization
stays correct without nesting wrappers.

Part of splitting the larger Scrapy integration fix
(`fix/scrapy-integration`) into reviewable pieces.

Author: vdusek

src/apify/scrapy/_logging_config.py

@@ -13,6 +13,11 @@
 _SUPPLEMENTAL_LOGGERS = ['filelock', 'hpack', 'httpcore', 'protego', 'twisted']
 _ALL_LOGGERS = _PRIMARY_LOGGERS + _SUPPLEMENTAL_LOGGERS
 
+# Mutable state shared with the Scrapy monkey-patch below. `initialize_logging` refreshes
+# `level`/`handler` on each call; the patch (installed once) reads them so it always applies the
+# latest configuration rather than values captured the first time it ran.
+_state: dict[str, Any] = {'level': 'INFO', 'handler': None, 'patched': False}
+
 
 def _configure_logger(name: str | None, logging_level: str, handler: logging.Handler) -> None:
     """Clear and reconfigure the logger."""
@@ -23,26 +28,39 @@ def _configure_logger(name: str | None, logging_level: str, handler: logging.Han
     logger.propagate = False
 
 
+def _configure_all_loggers() -> None:
+    """Apply the Apify handler and level to the root logger and all defined loggers."""
+    handler = _state['handler']
+    if handler is None:
+        return
+    for logger_name in [None, *_ALL_LOGGERS]:
+        _configure_logger(logger_name, _state['level'], handler)
+
+
 def initialize_logging() -> None:
     """Configure logging for Apify Actors and adjust Scrapy's logging settings."""
     # Retrieve Scrapy project settings and determine the logging level.
     settings = get_project_settings()
-    logging_level = settings.get('LOG_LEVEL', 'INFO')  # Default to INFO.
+    _state['level'] = settings.get('LOG_LEVEL', 'INFO')  # Default to INFO.
 
     # Create a custom handler with the Apify log formatter.
     handler = logging.StreamHandler()
     handler.setFormatter(ActorLogFormatter(include_logger_name=True))
+    _state['handler'] = handler
 
     # Configure the root logger and all other defined loggers.
-    for logger_name in [None, *_ALL_LOGGERS]:
-        _configure_logger(logger_name, logging_level, handler)
+    _configure_all_loggers()
+
+    # Monkey-patch Scrapy's logging to re-apply our settings whenever it reconfigures logging.
+    # Install the wrapper at most once, otherwise repeated calls would nest wrappers.
+    if _state['patched']:
+        return
 
-    # Monkey-patch Scrapy's logging configuration to re-apply our settings.
     original_configure_logging = scrapy_logging.configure_logging
 
     def new_configure_logging(*args: Any, **kwargs: Any) -> None:
         original_configure_logging(*args, **kwargs)
-        for logger_name in [None, *_ALL_LOGGERS]:
-            _configure_logger(logger_name, logging_level, handler)
+        _configure_all_loggers()
 
     scrapy_logging.configure_logging = new_configure_logging  # ty: ignore[invalid-assignment]
+    _state['patched'] = True