fix: log traceback in logger.exception() of Haystack loggers

haystack/logging.py

@@ -116,7 +116,7 @@ def exception(
         msg: str,
         *,
         _: Any = None,
-        exc_info: Any = None,
+        exc_info: Any = True,
         stack_info: Any = False,
         stacklevel: int = 1,
         **kwargs: Any,
@@ -152,12 +152,23 @@ def setLevel(self, level: int) -> None:
         """Set the logging level."""
 
 
-def patch_log_method_to_kwargs_only(func: typing.Callable) -> typing.Callable:
-    """A decorator to make sure that a function is only called with keyword arguments."""
+def patch_log_method_to_kwargs_only(func: typing.Callable, *, default_exc_info: Any = None) -> typing.Callable:
+    """
+    A decorator to make sure that a function is only called with keyword arguments.
+
+    :param func: The log method to wrap.
+    :param default_exc_info: The `exc_info` to pass when the caller omits it. Use `True` for `exception`.
+    """
 
     @functools.wraps(func)
     def _log_only_with_kwargs(
-        msg: str, *, _: Any = None, exc_info: Any = None, stack_info: Any = False, stacklevel: int = 1, **kwargs: Any
+        msg: str,
+        *,
+        _: Any = None,
+        exc_info: Any = default_exc_info,
+        stack_info: Any = False,
+        stacklevel: int = 1,
+        **kwargs: Any,
     ) -> typing.Callable:  # we need the `_` to avoid a syntax error
         existing_extra = kwargs.pop("extra", {})
         return func(
@@ -273,7 +284,7 @@ def getLogger(name: str) -> PatchedLogger:
     logger.warning = patch_log_method_to_kwargs_only(logger.warning)  # type: ignore
     logger.error = patch_log_method_to_kwargs_only(logger.error)  # type: ignore
     logger.critical = patch_log_method_to_kwargs_only(logger.critical)  # type: ignore
-    logger.exception = patch_log_method_to_kwargs_only(logger.exception)  # type: ignore
+    logger.exception = patch_log_method_to_kwargs_only(logger.exception, default_exc_info=True)  # type: ignore
     logger.fatal = patch_log_method_to_kwargs_only(logger.fatal)  # type: ignore
     logger.log = patch_log_with_level_method_to_kwargs_only(logger.log)  # type: ignore
 

releasenotes/notes/fix-logger-exception-traceback-3a4aaf6016812011.yaml

@@ -0,0 +1,6 @@
+---
+fixes:
+  - |
+    ``logger.exception()`` on loggers from ``haystack.logging.getLogger`` now logs the active traceback, as the
+    standard library does. Previously it logged only the message, without the stack trace, in both JSON and console
+    output. Passing ``exc_info`` explicitly still works.

test/test_logging.py

@@ -557,6 +557,28 @@ def test_various_levels(self, capfd: CaptureFixture, method: str, expected_level
             "module": "haystack.test_logging",
         }
 
+    def test_exception_logs_traceback(self, caplog: LogCaptureFixture) -> None:
+        logger = haystack_logging.getLogger("haystack.test_logging")
+
+        try:
+            1 / 0
+        except ZeroDivisionError:
+            logger.exception("An error happened")
+
+        record = caplog.records[0]
+        assert record.exc_info is not None
+        assert record.exc_info[0] is ZeroDivisionError
+
+    def test_exception_respects_explicit_exc_info(self, caplog: LogCaptureFixture) -> None:
+        logger = haystack_logging.getLogger("haystack.test_logging")
+
+        try:
+            1 / 0
+        except ZeroDivisionError:
+            logger.exception("An error happened", exc_info=False)
+
+        assert not caplog.records[0].exc_info
+
     def test_log(self, capfd: CaptureFixture) -> None:
         haystack_logging.configure_logging(use_json=True)
 
@@ -641,7 +663,7 @@ def test_haystack_logger_with_positional_args(self, method: str, expected_level:
         logger = haystack_logging.getLogger("haystack.test_logging")
         logger.setLevel(logging.DEBUG)
 
-        with pytest.raises(TypeError):
+        with pytest.raises(TypeError, match=rf"Logger\.{method}\(\) takes 1 positional argument"):
             getattr(logger, method)("Hello, structured logging %s!", "logging")
 
     @pytest.mark.parametrize(