opentelemetry-instrumentation: add unwrapping from dotted paths strings (#2919)

Author: xrmx

Diff for: CHANGELOG.md

@@ -21,6 +21,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   ([#2082](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/2082))
 - `opentelemetry-instrumentation-redis` Add additional attributes for methods create_index and search, rename those spans
   ([#2635](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/2635))
+- `opentelemetry-instrumentation` Add support for string based dotted module paths in unwrap
+  ([#2919](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/2919))
 
 ### Fixed
 

Diff for: opentelemetry-instrumentation/src/opentelemetry/instrumentation/utils.py

@@ -14,8 +14,9 @@
 
 import urllib.parse
 from contextlib import contextmanager
+from importlib import import_module
 from re import escape, sub
-from typing import Dict, Iterable, Sequence
+from typing import Dict, Iterable, Sequence, Union
 
 from wrapt import ObjectProxy
 
@@ -80,13 +81,30 @@ def http_status_to_status_code(
     return StatusCode.ERROR
 
 
-def unwrap(obj, attr: str):
+def unwrap(obj: Union[object, str], attr: str):
     """Given a function that was wrapped by wrapt.wrap_function_wrapper, unwrap it
 
+    The object containing the function to unwrap may be passed as dotted module path string.
+
     Args:
-        obj: Object that holds a reference to the wrapped function
+        obj: Object that holds a reference to the wrapped function or dotted import path as string
         attr (str): Name of the wrapped function
     """
+    if isinstance(obj, str):
+        try:
+            module_path, class_name = obj.rsplit(".", 1)
+        except ValueError as exc:
+            raise ImportError(
+                f"Cannot parse '{obj}' as dotted import path"
+            ) from exc
+        module = import_module(module_path)
+        try:
+            obj = getattr(module, class_name)
+        except AttributeError as exc:
+            raise ImportError(
+                f"Cannot import '{class_name}' from '{module}'"
+            ) from exc
+
     func = getattr(obj, attr, None)
     if func and isinstance(func, ObjectProxy) and hasattr(func, "__wrapped__"):
         setattr(obj, attr, func.__wrapped__)

Diff for: opentelemetry-instrumentation/tests/test_utils.py

@@ -15,6 +15,8 @@
 import unittest
 from http import HTTPStatus
 
+from wrapt import ObjectProxy, wrap_function_wrapper
+
 from opentelemetry.context import (
     _SUPPRESS_HTTP_INSTRUMENTATION_KEY,
     _SUPPRESS_INSTRUMENTATION_KEY,
@@ -29,10 +31,19 @@
     is_instrumentation_enabled,
     suppress_http_instrumentation,
     suppress_instrumentation,
+    unwrap,
 )
 from opentelemetry.trace import StatusCode
 
 
+class WrappedClass:
+    def method(self):
+        pass
+
+    def wrapper_method(self):
+        pass
+
+
 class TestUtils(unittest.TestCase):
     # See https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/trace/semantic_conventions/http.md#status
     def test_http_status_to_status_code(self):
@@ -240,3 +251,75 @@ def test_suppress_http_instrumentation_key(self):
             self.assertTrue(get_value(_SUPPRESS_HTTP_INSTRUMENTATION_KEY))
 
         self.assertIsNone(get_value(_SUPPRESS_HTTP_INSTRUMENTATION_KEY))
+
+
+class UnwrapTestCase(unittest.TestCase):
+    @staticmethod
+    def _wrap_method():
+        return wrap_function_wrapper(
+            WrappedClass, "method", WrappedClass.wrapper_method
+        )
+
+    def test_can_unwrap_object_attribute(self):
+        self._wrap_method()
+        instance = WrappedClass()
+        self.assertTrue(isinstance(instance.method, ObjectProxy))
+
+        unwrap(WrappedClass, "method")
+        self.assertFalse(isinstance(instance.method, ObjectProxy))
+
+    def test_can_unwrap_object_attribute_as_string(self):
+        self._wrap_method()
+        instance = WrappedClass()
+        self.assertTrue(isinstance(instance.method, ObjectProxy))
+
+        unwrap("tests.test_utils.WrappedClass", "method")
+        self.assertFalse(isinstance(instance.method, ObjectProxy))
+
+    def test_raises_import_error_if_path_not_well_formed(self):
+        self._wrap_method()
+        instance = WrappedClass()
+        self.assertTrue(isinstance(instance.method, ObjectProxy))
+
+        with self.assertRaisesRegex(
+            ImportError, "Cannot parse '' as dotted import path"
+        ):
+            unwrap("", "method")
+
+        unwrap(WrappedClass, "method")
+        self.assertFalse(isinstance(instance.method, ObjectProxy))
+
+    def test_raises_import_error_if_cannot_find_module(self):
+        self._wrap_method()
+        instance = WrappedClass()
+        self.assertTrue(isinstance(instance.method, ObjectProxy))
+
+        with self.assertRaisesRegex(ImportError, "No module named 'does'"):
+            unwrap("does.not.exist.WrappedClass", "method")
+
+        unwrap(WrappedClass, "method")
+        self.assertFalse(isinstance(instance.method, ObjectProxy))
+
+    def test_raises_import_error_if_cannot_find_object(self):
+        self._wrap_method()
+        instance = WrappedClass()
+        self.assertTrue(isinstance(instance.method, ObjectProxy))
+
+        with self.assertRaisesRegex(
+            ImportError, "Cannot import 'NotWrappedClass' from"
+        ):
+            unwrap("tests.test_utils.NotWrappedClass", "method")
+
+        unwrap(WrappedClass, "method")
+        self.assertFalse(isinstance(instance.method, ObjectProxy))
+
+    # pylint: disable=no-self-use
+    def test_does_nothing_if_cannot_find_attribute(self):
+        instance = WrappedClass()
+        unwrap(instance, "method_not_found")
+
+    def test_does_nothing_if_attribute_is_not_from_wrapt(self):
+        instance = WrappedClass()
+        self.assertFalse(isinstance(instance.method, ObjectProxy))
+        unwrap(WrappedClass, "method")
+        self.assertFalse(isinstance(instance.method, ObjectProxy))