sdk/metrics: copy attributes dict to prevent post-recording mutation

CHANGELOG.md

@@ -12,6 +12,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## Unreleased
 
+- `opentelemetry-sdk`: Fix mutable attributes reference in metrics: attributes passed to instrument `add`/`record` are now copied so that subsequent mutations to the caller's dict do not affect recorded data points
+  ([#4610](https://github.com/open-telemetry/opentelemetry-python/issues/4610))
 - `opentelemetry-sdk`: Add `create_logger_provider`/`configure_logger_provider` to declarative file configuration, enabling LoggerProvider instantiation from config files without reading env vars
   ([#4990](https://github.com/open-telemetry/opentelemetry-python/pull/4990))
 - `opentelemetry-sdk`: Add `service` resource detector support to declarative file configuration via `detection_development.detectors[].service`

opentelemetry-sdk/src/opentelemetry/sdk/metrics/_internal/_view_instrument_match.py

@@ -98,7 +98,7 @@ def consume_measurement(
                 if key in self._view._attribute_keys:
                     attributes[key] = value
         elif measurement.attributes is not None:
-            attributes = measurement.attributes
+            attributes = dict(measurement.attributes)
         else:
             attributes = {}
 

opentelemetry-sdk/tests/metrics/test_view_instrument_match.py

@@ -266,6 +266,51 @@ def test_collect(self):
         self.assertEqual(number_data_point.attributes, {"c": "d"})
         self.assertEqual(number_data_point.value, 0)
 
+    def test_consume_measurement_attributes_are_copied(self):
+        """Mutating the attributes dict after recording must not affect stored data points."""
+        instrument1 = _Counter(
+            "instrument1",
+            Mock(),
+            Mock(),
+            description="description",
+            unit="unit",
+        )
+        instrument1.instrumentation_scope = self.mock_instrumentation_scope
+        view_instrument_match = _ViewInstrumentMatch(
+            view=View(
+                instrument_name="instrument1",
+                name="name",
+                aggregation=DefaultAggregation(),
+            ),
+            instrument=instrument1,
+            instrument_class_aggregation=MagicMock(
+                **{"__getitem__.return_value": DefaultAggregation()}
+            ),
+        )
+
+        attributes = {"key": "original"}
+        view_instrument_match.consume_measurement(
+            Measurement(
+                value=1,
+                time_unix_nano=time_ns(),
+                instrument=instrument1,
+                context=Context(),
+                attributes=attributes,
+            )
+        )
+
+        # Mutate the original dict after recording
+        attributes["key"] = "mutated"
+
+        number_data_points = view_instrument_match.collect(
+            AggregationTemporality.CUMULATIVE, 0
+        )
+        number_data_points = list(number_data_points)
+        self.assertEqual(len(number_data_points), 1)
+        self.assertEqual(
+            number_data_points[0].attributes, {"key": "original"}
+        )
+
     @patch(
         "opentelemetry.sdk.metrics._internal._view_instrument_match.time_ns",
         side_effect=[0, 1, 2],