Fix import logic for importlib.metadata and pkg_resources (#1399)

* Rework imports of importlib.metadata and pkg_resources

* Fix entrypoints kwargs

* Tweak comment

* Adjust tests for new package version checking

Author: TimPansino

newrelic/admin/__init__.py

@@ -121,21 +121,29 @@ def load_internal_plugins():
 
 def load_external_plugins():
     try:
-        # Preferred after Python 3.10
-        if sys.version_info >= (3, 10):
-            from importlib.metadata import entry_points
-        # Introduced in Python 3.8
-        elif sys.version_info >= (3, 8) and sys.version_info < (3, 9):
-            from importlib_metadata import entry_points
-        # Removed in Python 3.12
-        else:
-            from pkg_resources import iter_entry_points as entry_points
+        # importlib.metadata was introduced into the standard library starting in Python 3.8.
+        from importlib.metadata import entry_points
     except ImportError:
-        return
+        try:
+            # importlib_metadata is a backport library installable from PyPI.
+            from importlib_metadata import entry_points
+        except ImportError:
+            try:
+                # Fallback to pkg_resources, which is available in older versions of setuptools.
+                from pkg_resources import iter_entry_points as entry_points
+            except ImportError:
+                return
 
     group = "newrelic.admin"
 
-    for entrypoint in entry_points(group=group):
+    try:
+        # group kwarg was only added to importlib.metadata.entry_points in Python 3.10.
+        _entry_points = entry_points(group=group)
+    except TypeError:
+        # Grab entire entry_points dictionary and select group from it.
+        _entry_points = entry_points().get(group, ())
+
+    for entrypoint in _entry_points:
         __import__(entrypoint.module_name)
 
 

newrelic/common/package_version_utils.py

@@ -95,23 +95,33 @@ def _get_package_version(name):
             except Exception:
                 pass
 
-    # importlib was introduced into the standard library starting in Python3.8.
-    if "importlib" in sys.modules and hasattr(sys.modules["importlib"], "metadata"):
+    importlib_metadata = None
+    # importlib.metadata was introduced into the standard library starting in Python 3.8.
+    importlib_metadata = getattr(sys.modules.get("importlib", None), "metadata", None)
+    if importlib_metadata is None:
+        # importlib_metadata is a backport library installable from PyPI.
         try:
-            # In Python3.10+ packages_distribution can be checked for as well
-            if hasattr(sys.modules["importlib"].metadata, "packages_distributions"):
-                distributions = sys.modules["importlib"].metadata.packages_distributions()
+            import importlib_metadata
+        except ImportError:
+            pass
+
+    if importlib_metadata is not None:
+        try:
+            # In Python 3.10+ packages_distribution can be checked for as well.
+            if hasattr(importlib_metadata, "packages_distributions"):
+                distributions = importlib_metadata.packages_distributions()
                 distribution_name = distributions.get(name, name)
                 distribution_name = distribution_name[0] if isinstance(distribution_name, list) else distribution_name
             else:
                 distribution_name = name
 
-            version = sys.modules["importlib"].metadata.version(distribution_name)
+            version = importlib_metadata.version(distribution_name)
             if version not in NULL_VERSIONS:
                 return version
         except Exception:
             pass
 
+    # Fallback to pkg_resources, which is available in older versions of setuptools.
     if "pkg_resources" in sys.modules:
         try:
             version = sys.modules["pkg_resources"].get_distribution(name).version

newrelic/config.py

@@ -4092,21 +4092,29 @@ def _process_module_builtin_defaults():
 
 def _process_module_entry_points():
     try:
-        # Preferred after Python 3.10
-        if sys.version_info >= (3, 10):
-            from importlib.metadata import entry_points
-        # Introduced in Python 3.8
-        elif sys.version_info >= (3, 8) and sys.version_info < (3, 9):
-            from importlib_metadata import entry_points
-        # Removed in Python 3.12
-        else:
-            from pkg_resources import iter_entry_points as entry_points
+        # importlib.metadata was introduced into the standard library starting in Python 3.8.
+        from importlib.metadata import entry_points
     except ImportError:
-        return
+        try:
+            # importlib_metadata is a backport library installable from PyPI.
+            from importlib_metadata import entry_points
+        except ImportError:
+            try:
+                # Fallback to pkg_resources, which is available in older versions of setuptools.
+                from pkg_resources import iter_entry_points as entry_points
+            except ImportError:
+                return
 
     group = "newrelic.hooks"
 
-    for entrypoint in entry_points(group=group):
+    try:
+        # group kwarg was only added to importlib.metadata.entry_points in Python 3.10.
+        _entry_points = entry_points(group=group)
+    except TypeError:
+        # Grab entire entry_points dictionary and select group from it.
+        _entry_points = entry_points().get(group, ())
+
+    for entrypoint in _entry_points:
         target = entrypoint.name
 
         if target in _module_import_hook_registry:
@@ -4164,21 +4172,29 @@ def _setup_instrumentation():
 
 def _setup_extensions():
     try:
-        # Preferred after Python 3.10
-        if sys.version_info >= (3, 10):
-            from importlib.metadata import entry_points
-        # Introduced in Python 3.8
-        elif sys.version_info >= (3, 8) and sys.version_info < (3, 9):
-            from importlib_metadata import entry_points
-        # Removed in Python 3.12
-        else:
-            from pkg_resources import iter_entry_points as entry_points
+        # importlib.metadata was introduced into the standard library starting in Python 3.8.
+        from importlib.metadata import entry_points
     except ImportError:
-        return
+        try:
+            # importlib_metadata is a backport library installable from PyPI.
+            from importlib_metadata import entry_points
+        except ImportError:
+            try:
+                # Fallback to pkg_resources, which is available in older versions of setuptools.
+                from pkg_resources import iter_entry_points as entry_points
+            except ImportError:
+                return
 
     group = "newrelic.extension"
 
-    for entrypoint in entry_points(group=group):
+    try:
+        # group kwarg was only added to importlib.metadata.entry_points in Python 3.10.
+        _entry_points = entry_points(group=group)
+    except TypeError:
+        # Grab entire entry_points dictionary and select group from it.
+        _entry_points = entry_points().get(group, ())
+
+    for entrypoint in _entry_points:
         __import__(entrypoint.module_name)
         module = sys.modules[entrypoint.module_name]
         module.initialize()

tests/agent_unittests/test_package_version_utils.py

@@ -103,7 +103,16 @@ def test_get_package_version_tuple(monkeypatch, attr, value, expected_value):
 
 @SKIP_IF_NOT_IMPORTLIB_METADATA
 @validate_function_called("importlib.metadata", "version")
-def test_importlib_metadata():
+def test_importlib_dot_metadata():
+    # Test for importlib.metadata from the standard library.
+    version = get_package_version("pytest")
+    assert version not in NULL_VERSIONS, version
+
+
+@SKIP_IF_IMPORTLIB_METADATA
+@validate_function_called("importlib_metadata", "version")
+def test_importlib_underscore_metadata():
+    # Test for importlib_metadata, a backport library available on PyPI.
     version = get_package_version("pytest")
     assert version not in NULL_VERSIONS, version
 
@@ -117,7 +126,9 @@ def test_mapping_import_to_distribution_packages():
 
 @SKIP_IF_IMPORTLIB_METADATA
 @validate_function_called("pkg_resources", "get_distribution")
-def test_pkg_resources_metadata():
+def test_pkg_resources_metadata(monkeypatch):
+    # Prevent importlib_metadata from being used by these tests
+    monkeypatch.setitem(sys.modules, "importlib_metadata", None)
     version = get_package_version("pytest")
     assert version not in NULL_VERSIONS, version