Redirect errors/tracebacks to the right logging stream

workflow/src/legenddataflow/log.py

@@ -1,10 +1,28 @@
 import logging
+import sys
+import traceback
 from logging.config import dictConfig
 from pathlib import Path
 
 from dbetto import Props
 
 
+class StreamToLogger:
+    """File-like stream object that redirects writes to a logger instance."""
+
+    def __init__(self, logger, log_level=logging.ERROR):
+        self.logger = logger
+        self.log_level = log_level
+        self.linebuf = ""
+
+    def write(self, buf):
+        for line in buf.rstrip().splitlines():
+            self.logger.log(self.log_level, line.rstrip())
+
+    def flush(self):
+        pass
+
+
 def build_log(
     config_dict: dict, log_file: str | None = None, fallback: str = "prod"
 ) -> logging.Logger:
@@ -37,4 +55,21 @@ def build_log(
 
         log = logging.getLogger(fallback)
 
+    # Redirect stderr to the logger (using the error level)
+    sys.stderr = StreamToLogger(log, logging.ERROR)
+
+    # Extract the stream from the logger's file handler.
+    log_stream = None
+    for handler in log.handlers:
+        if hasattr(handler, "stream"):
+            log_stream = handler.stream
+            break
+    if log_stream is None:
+        log_stream = sys.stdout
+
+    def excepthook(exc_type, exc_value, exc_traceback):
+        traceback.print_exception(exc_type, exc_value, exc_traceback, file=log_stream)
+
+    sys.excepthook = excepthook
+
     return log