feat(logging): add log_path parameter to setup_logger for file output

daft/logging.py

@@ -2,6 +2,7 @@
 
 import logging
 import typing
+from pathlib import Path
 
 from daft import refresh_logger
 
@@ -39,6 +40,7 @@ def setup_logger(
     daft_only: bool = False,
     logformat: str = "%(asctime)s - %(name)s - %(levelname)s - %(message)s",
     datefmt: str = "%Y-%m-%d %H:%M:%S.%s".format(),
+    log_path: str | None = None,
 ) -> None:
     """Setup Daft logger with a specific log level, optional prefix filtering, and Rust sync.
 
@@ -48,6 +50,7 @@ def setup_logger(
         daft_only (bool, optional): Whether to only log messages from the Daft module. Defaults to False.
         logformat (str, optional): The log format to use. Defaults to "%(asctime)s - %(name)s - %(levelname)s - %(message)s".
         datefmt (str, optional): The date format to use. Defaults to '%Y-%m-%d %H:%M:%S.%s'.format().
+        log_path (str | None, optional): Path to a log file to append Daft logs to. If None, logs are only emitted to the configured stream handlers. Defaults to None.
 
     Raises:
         ValueError: If the log level is not valid.
@@ -68,6 +71,22 @@ def setup_logger(
 
     for handler in root_logger.handlers:
         handler.filters.clear()
+        # remove daft managed file handler if present
+        if isinstance(handler, _DaftFileHandler):
+            root_logger.removeHandler(handler)
+            handler.close()
+
+    if log_path is not None:
+        path = Path(log_path)
+        if "~" in str(path):
+            path = path.expanduser()
+        path = path.resolve()
+        path.parent.mkdir(parents=True, exist_ok=True)
+
+        file_handler = _DaftFileHandler(path)
+        file_handler.setLevel(numeric_level)
+        file_handler.setFormatter(logging.Formatter(logformat, datefmt=datefmt))
+        root_logger.addHandler(file_handler)
 
     if daft_only:
         for handler in root_logger.handlers:
@@ -79,3 +98,7 @@ def setup_logger(
                 handler.addFilter(lambda r, p=prefix: not r.name.startswith(p))  # type: ignore
 
     refresh_logger()
+
+
+class _DaftFileHandler(logging.FileHandler):
+    pass