Allow reraising the root exception if instrumentation fails (open-telemetry#3545)

* Allow reraising the root exception if instrumentation fails

I would rather completely fail startup in my services if instrumentation fails for whatever reason instead of just logging an exception and continuing.

Use case:

from opentelemetry import autoinstrumentation

autoinstrumentation.initialize(swallow_exceptions=False)

* Fix lint

* Type hinting, re-raise original exception

* One more type hint to indicate None return

---------

Co-authored-by: Riccardo Magliocchetti <[email protected]>

Author: phillipuniverse

CHANGELOG.md

@@ -69,6 +69,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   ([#3517](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/3517))
 - `opentelemetry-instrumentation-httpx` Add support for HTTP metrics
   ([#3513](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/3513))
+- `opentelemetry-instrumentation` Allow re-raising exception when instrumentation fails
+  ([#3545](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/3545))
 
 ### Deprecated
 

opentelemetry-instrumentation/src/opentelemetry/instrumentation/auto_instrumentation/__init__.py

@@ -118,8 +118,12 @@ def run() -> None:
     execl(executable, executable, *args.command_args)
 
 
-def initialize():
-    """Setup auto-instrumentation, called by the sitecustomize module"""
+def initialize(*, swallow_exceptions: bool = True) -> None:
+    """
+    Setup auto-instrumentation, called by the sitecustomize module
+
+    :param swallow_exceptions: Whether or not to propagate instrumentation exceptions to the caller. Exceptions are logged and swallowed by default.
+    """
     # prevents auto-instrumentation of subprocesses if code execs another python process
     if "PYTHONPATH" in environ:
         environ["PYTHONPATH"] = _python_path_without_directory(
@@ -131,5 +135,7 @@ def initialize():
         distro.configure()
         _load_configurators()
         _load_instrumentors(distro)
-    except Exception:  # pylint: disable=broad-except
+    except Exception as exc:  # pylint: disable=broad-except
         _logger.exception("Failed to auto initialize OpenTelemetry")
+        if not swallow_exceptions:
+            raise exc

opentelemetry-instrumentation/tests/auto_instrumentation/test_initialize.py

@@ -59,3 +59,16 @@ def test_handles_exceptions(self, load_distro_mock, logger_mock):
         logger_mock.exception.assert_called_once_with(
             "Failed to auto initialize OpenTelemetry"
         )
+
+    @patch("opentelemetry.instrumentation.auto_instrumentation._logger")
+    @patch("opentelemetry.instrumentation.auto_instrumentation._load_distro")
+    def test_reraises_exceptions(self, load_distro_mock, logger_mock):
+        # pylint:disable=no-self-use
+        load_distro_mock.side_effect = ValueError("inner exception")
+        with self.assertRaises(ValueError) as em:
+            auto_instrumentation.initialize(swallow_exceptions=False)
+            logger_mock.exception.assert_called_once_with(
+                "Failed to auto initialize OpenTelemetry"
+            )
+
+        self.assertEqual("inner exception", str(em.exception))