opentelemetry-instrumentation: expose a way to init autoinstrumentation programmatically (#3273)

* opentelemetry-instrumentation: expose a way to init autoinstrumentation

* Please pylint

* Add changelog

* Fix example

* Fix whitespace in README

* Add a note aboout ordering of initialization vs imports

* Don't touch PYTHONPATH if not set

* Update opentelemetry-instrumentation/README.rst

Co-authored-by: Emídio Neto <9735060+emdneto@users.noreply.github.com>

* Update CHANGELOG.md

* Update opentelemetry-instrumentation/README.rst

Co-authored-by: Leighton Chen <lechen@microsoft.com>

---------

Co-authored-by: Emídio Neto <9735060+emdneto@users.noreply.github.com>
Co-authored-by: Leighton Chen <lechen@microsoft.com>

opentelemetry-instrumentation/tests/auto_instrumentation/test_initialize.py

@@ -0,0 +1,61 @@
+# Copyright The OpenTelemetry Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+# type: ignore
+
+from os import environ
+from os.path import abspath, dirname, pathsep
+from unittest import TestCase
+from unittest.mock import patch
+
+from opentelemetry.instrumentation import auto_instrumentation
+
+# TODO: convert to assertNoLogs instead of mocking logger when 3.10 is baseline
+
+
+class TestInitialize(TestCase):
+    auto_instrumentation_path = dirname(abspath(auto_instrumentation.__file__))
+
+    @patch.dict("os.environ", {}, clear=True)
+    @patch("opentelemetry.instrumentation.auto_instrumentation._logger")
+    def test_handles_pythonpath_not_set(self, logger_mock):
+        auto_instrumentation.initialize()
+        self.assertNotIn("PYTHONPATH", environ)
+        logger_mock.exception.assert_not_called()
+
+    @patch.dict("os.environ", {"PYTHONPATH": "."})
+    @patch("opentelemetry.instrumentation.auto_instrumentation._logger")
+    def test_handles_pythonpath_set(self, logger_mock):
+        auto_instrumentation.initialize()
+        self.assertEqual(environ["PYTHONPATH"], ".")
+        logger_mock.exception.assert_not_called()
+
+    @patch.dict(
+        "os.environ",
+        {"PYTHONPATH": auto_instrumentation_path + pathsep + "foo"},
+    )
+    @patch("opentelemetry.instrumentation.auto_instrumentation._logger")
+    def test_clears_auto_instrumentation_path(self, logger_mock):
+        auto_instrumentation.initialize()
+        self.assertEqual(environ["PYTHONPATH"], "foo")
+        logger_mock.exception.assert_not_called()
+
+    @patch("opentelemetry.instrumentation.auto_instrumentation._logger")
+    @patch("opentelemetry.instrumentation.auto_instrumentation._load_distro")
+    def test_handles_exceptions(self, load_distro_mock, logger_mock):
+        # pylint:disable=no-self-use
+        load_distro_mock.side_effect = ValueError
+        auto_instrumentation.initialize()
+        logger_mock.exception.assert_called_once_with(
+            "Failed to auto initialize OpenTelemetry"
+        )

opentelemetry-instrumentation/tests/auto_instrumentation/test_sitecustomize.py

@@ -0,0 +1,28 @@
+# Copyright The OpenTelemetry Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+# type: ignore
+
+from unittest import TestCase
+from unittest.mock import patch
+
+
+class TestSiteCustomize(TestCase):
+    # pylint:disable=import-outside-toplevel,unused-import,no-self-use
+    @patch("opentelemetry.instrumentation.auto_instrumentation.initialize")
+    def test_sitecustomize_side_effects(self, initialize_mock):
+        initialize_mock.assert_not_called()
+
+        import opentelemetry.instrumentation.auto_instrumentation.sitecustomize  # NOQA
+
+        initialize_mock.assert_called_once()