Fix logging configuration not propagating to child parser processes (#646)

* Initial plan

* Fix logging configuration propagation to child parser processes

- Add _configure_logging() helper function to set up logging in child processes
- Modified cli_parse() to accept log_level and log_file parameters
- Pass current logging configuration from parent to child processes
- Logging warnings/errors from child processes now properly display

Fixes issue where logging handlers in parent process were not inherited by
child processes created via multiprocessing.Process(). Child processes now
configure their own logging with the same settings as the parent.

Tested with sample files and confirmed warnings from DNS exceptions in child
processes are now visible.

Co-authored-by: seanthegeek <44679+seanthegeek@users.noreply.github.com>

* Address code review feedback on logging configuration

- Use exact type check (type(h) is logging.StreamHandler) instead of isinstance
  to avoid confusion with FileHandler subclass
- Catch specific exceptions (IOError, OSError, PermissionError) instead of
  bare Exception when creating FileHandler
- Kept logging.ERROR as default to maintain consistency with existing behavior

Co-authored-by: seanthegeek <44679+seanthegeek@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: seanthegeek <44679+seanthegeek@users.noreply.github.com>

parsedmarc/cli.py

@@ -67,6 +67,51 @@ def _str_to_list(s):
     return list(map(lambda i: i.lstrip(), _list))
 
 
+def _configure_logging(log_level, log_file=None):
+    """
+    Configure logging for the current process.
+    This is needed for child processes to properly log messages.
+    
+    Args:
+        log_level: The logging level (e.g., logging.DEBUG, logging.WARNING)
+        log_file: Optional path to log file
+    """
+    # Get the logger
+    from parsedmarc.log import logger
+    
+    # Set the log level
+    logger.setLevel(log_level)
+    
+    # Add StreamHandler with formatter if not already present
+    # Check if we already have a StreamHandler to avoid duplicates
+    # Use exact type check to distinguish from FileHandler subclass
+    has_stream_handler = any(
+        type(h) is logging.StreamHandler
+        for h in logger.handlers
+    )
+    
+    if not has_stream_handler:
+        formatter = logging.Formatter(
+            fmt="%(levelname)8s:%(filename)s:%(lineno)d:%(message)s",
+            datefmt="%Y-%m-%d:%H:%M:%S",
+        )
+        handler = logging.StreamHandler()
+        handler.setFormatter(formatter)
+        logger.addHandler(handler)
+    
+    # Add FileHandler if log_file is specified
+    if log_file:
+        try:
+            fh = logging.FileHandler(log_file, "a")
+            formatter = logging.Formatter(
+                "%(asctime)s - %(levelname)s - [%(filename)s:%(lineno)d] - %(message)s"
+            )
+            fh.setFormatter(formatter)
+            logger.addHandler(fh)
+        except (IOError, OSError, PermissionError) as error:
+            logger.warning("Unable to write to log file: {}".format(error))
+
+
 def cli_parse(
     file_path,
     sa,
@@ -79,8 +124,29 @@ def cli_parse(
     reverse_dns_map_url,
     normalize_timespan_threshold_hours,
     conn,
+    log_level=logging.ERROR,
+    log_file=None,
 ):
-    """Separated this function for multiprocessing"""
+    """Separated this function for multiprocessing
+    
+    Args:
+        file_path: Path to the report file
+        sa: Strip attachment payloads flag
+        nameservers: List of nameservers
+        dns_timeout: DNS timeout
+        ip_db_path: Path to IP database
+        offline: Offline mode flag
+        always_use_local_files: Always use local files flag
+        reverse_dns_map_path: Path to reverse DNS map
+        reverse_dns_map_url: URL to reverse DNS map
+        normalize_timespan_threshold_hours: Timespan threshold
+        conn: Pipe connection for IPC
+        log_level: Logging level for this process
+        log_file: Optional path to log file
+    """
+    # Configure logging in this child process
+    _configure_logging(log_level, log_file)
+    
     try:
         file_results = parse_report_file(
             file_path,
@@ -1461,6 +1527,10 @@ def _main():
     if n_procs < 1:
         n_procs = 1
 
+    # Capture the current log level to pass to child processes
+    current_log_level = logger.level
+    current_log_file = opts.log_file
+
     for batch_index in range((len(file_paths) + n_procs - 1) // n_procs):
         processes = []
         connections = []
@@ -1486,6 +1556,8 @@ def _main():
                     opts.reverse_dns_map_url,
                     opts.normalize_timespan_threshold_hours,
                     child_conn,
+                    current_log_level,
+                    current_log_file,
                 ),
             )
             processes.append(process)