Celery duplicated instrumentation (#2342)

* * Adding (failing) testcase to cover Issue #2029

* * move Instance variables to class variables. Since the object in question will be a singelton. This will resolve #2029 where multiple calls to the instrumentation will assign Null values.

* * black formatting

* * Changelog stub entry, PR # to follow

* * updating the pullrequest number

* * remove superfluous constructor

* * moving Change log to unreleased section

---------

Co-authored-by: Shalev Roda <65566801+shalevr@users.noreply.github.com>

CHANGELOG.md

@@ -8,6 +8,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ## Unreleased
 
 ### Fixed
+- `opentelemetry-instrumentation-celery` Allow Celery instrumentation to be installed multiple times
+  ([#2342](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/2342))
 - Align gRPC span status codes to OTEL specification ([#1756](https://github.com/open-telemetry/opentelemetry-python-contrib/issues/1756))
 
 ## Version 1.23.0/0.44b0 (2024-02-23)

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

@@ -113,10 +113,8 @@ celery_getter = CeleryGetter()
 
 
 class CeleryInstrumentor(BaseInstrumentor):
-    def __init__(self):
-        super().__init__()
-        self.metrics = None
-        self.task_id_to_start_time = {}
+    metrics = None
+    task_id_to_start_time = {}
 
     def instrumentation_dependencies(self) -> Collection[str]:
         return _instruments

instrumentation/opentelemetry-instrumentation-celery/tests/test_duplicate.py

@@ -0,0 +1,30 @@
+# 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.
+
+import unittest
+
+from opentelemetry.instrumentation.celery import CeleryInstrumentor
+
+
+class TestUtils(unittest.TestCase):
+    def test_duplicate_instrumentaion(self):
+        first = CeleryInstrumentor()
+        first.instrument()
+        second = CeleryInstrumentor()
+        second.instrument()
+        CeleryInstrumentor().uninstrument()
+        self.assertIsNotNone(first.metrics)
+        self.assertIsNotNone(second.metrics)
+        self.assertEqual(first.task_id_to_start_time, {})
+        self.assertEqual(second.task_id_to_start_time, {})