opentelemetry-instrumentation-system-metrics: fix running on Google Cloud Run (open-telemetry#3533)

* opentelemetry-instrumentation-system-metrics: fix running on Google Cloud Run

psutil fails reading context switches fails on Google Cloud Run, so
before setting up the observable counter trying to read the values check
we are actually being able to do so.

* Please pylint

Author: xrmx

CHANGELOG.md

@@ -13,6 +13,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Fixed
 
+- `opentelemetry-instrumentation-system-metrics`: fix loading on Google Cloud Run
+  ([#3533](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/3533))
 - `opentelemetry-instrumentation-fastapi`: fix wrapping of middlewares
   ([#3012](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/3012))
 - `opentelemetry-instrumentation-urllib3`: proper bucket boundaries in stable semconv http duration metrics

instrumentation/opentelemetry-instrumentation-system-metrics/src/opentelemetry/instrumentation/system_metrics/__init__.py

@@ -395,7 +395,10 @@ def _instrument(self, **kwargs: Any):
                 self._meter, callbacks=[self._get_cpu_utilization]
             )
 
-        if "process.context_switches" in self._config:
+        if (
+            "process.context_switches" in self._config
+            and self._can_read_context_switches()
+        ):
             self._meter.create_observable_counter(
                 name="process.context_switches",
                 callbacks=[self._get_context_switches],
@@ -482,7 +485,10 @@ def _instrument(self, **kwargs: Any):
                 unit="1",
             )
 
-        if "process.runtime.context_switches" in self._config:
+        if (
+            "process.runtime.context_switches" in self._config
+            and self._can_read_context_switches()
+        ):
             self._meter.create_observable_counter(
                 name=f"process.runtime.{self._python_implementation}.context_switches",
                 callbacks=[self._get_runtime_context_switches],
@@ -493,6 +499,14 @@ def _instrument(self, **kwargs: Any):
     def _uninstrument(self, **kwargs: Any):
         pass
 
+    def _can_read_context_switches(self) -> bool:
+        """On Google Cloud Run psutil is not able to read context switches, catch it before creating the observable instrument"""
+        try:
+            self._proc.num_ctx_switches()
+            return True
+        except NotImplementedError:
+            return False
+
     def _get_open_file_descriptors(
         self, options: CallbackOptions
     ) -> Iterable[Observation]:

instrumentation/opentelemetry-instrumentation-system-metrics/tests/test_system_metrics.py

@@ -12,7 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-# pylint: disable=protected-access
+# pylint: disable=protected-access,too-many-lines
 
 import sys
 from collections import namedtuple
@@ -235,14 +235,28 @@ def _assert_metrics(self, observer_name, reader, expected):
                                 assertions += 1
         self.assertEqual(len(expected), assertions)
 
-    def _test_metrics(self, observer_name, expected):
+    @staticmethod
+    def _setup_instrumentor() -> InMemoryMetricReader:
         reader = InMemoryMetricReader()
         meter_provider = MeterProvider(metric_readers=[reader])
 
         system_metrics = SystemMetricsInstrumentor()
         system_metrics.instrument(meter_provider=meter_provider)
+        return reader
+
+    def _test_metrics(self, observer_name, expected):
+        reader = self._setup_instrumentor()
         self._assert_metrics(observer_name, reader, expected)
 
+    def _assert_metrics_not_found(self, observer_name):
+        reader = self._setup_instrumentor()
+        seen_metrics = set()
+        for resource_metrics in reader.get_metrics_data().resource_metrics:
+            for scope_metrics in resource_metrics.scope_metrics:
+                for metric in scope_metrics.metrics:
+                    seen_metrics.add(metric.name)
+        self.assertNotIn(observer_name, seen_metrics)
+
     # This patch is added here to stop psutil from raising an exception
     # because we're patching cpu_times
     # pylint: disable=unused-argument
@@ -855,6 +869,14 @@ def test_context_switches(self, mock_process_num_ctx_switches):
         ]
         self._test_metrics("process.context_switches", expected)
 
+    @mock.patch("psutil.Process.num_ctx_switches")
+    def test_context_switches_not_implemented_error(
+        self, mock_process_num_ctx_switches
+    ):
+        mock_process_num_ctx_switches.side_effect = NotImplementedError
+
+        self._assert_metrics_not_found("process.context_switches")
+
     @mock.patch("psutil.Process.num_threads")
     def test_thread_count(self, mock_process_thread_num):
         mock_process_thread_num.configure_mock(**{"return_value": 42})
@@ -947,6 +969,16 @@ def test_runtime_context_switches(self, mock_process_num_ctx_switches):
             f"process.runtime.{self.implementation}.context_switches", expected
         )
 
+    @mock.patch("psutil.Process.num_ctx_switches")
+    def test_runtime_context_switches_not_implemented_error(
+        self, mock_process_num_ctx_switches
+    ):
+        mock_process_num_ctx_switches.side_effect = NotImplementedError
+
+        self._assert_metrics_not_found(
+            f"process.runtime.{self.implementation}.context_switches",
+        )
+
     @mock.patch("psutil.Process.num_threads")
     def test_runtime_thread_count(self, mock_process_thread_num):
         mock_process_thread_num.configure_mock(**{"return_value": 42})