Ensure httpx non-client methods are instrumented (#2538)

* Ensure httpx non-client methods are instrumented

* Update changelog

* Added subTest to distinguish tests inside a loop

* Updated changelog

* Add a comment explaining private attribute usage

---------

Co-authored-by: Diego Hurtado <ocelotl@users.noreply.github.com>

CHANGELOG.md

@@ -42,7 +42,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Fixed
 
-- `opentelemetry-instrumentation-dbapi` Fix compatibility with Psycopg3 to extract libpq build version (#2500)[https://github.com/open-telemetry/opentelemetry-python-contrib/pull/2500]
+- `opentelemetry-instrumentation-dbapi` Fix compatibility with Psycopg3 to extract libpq build version
+  ([#2500](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/2500))
+- `opentelemetry-instrumentation-httpx` Ensure httpx.get or httpx.request like methods are instrumented
+  ([#2538](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/2538))
 - `opentelemetry-instrumentation-grpc` AioClientInterceptor should propagate with a Metadata object
   ([#2363](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/2363))
 - `opentelemetry-instrumentation-boto3sqs` Instrument Session and resource

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

@@ -564,11 +564,13 @@ def _instrument(self, **kwargs):
         tracer_provider = kwargs.get("tracer_provider")
         _InstrumentedClient._tracer_provider = tracer_provider
         _InstrumentedAsyncClient._tracer_provider = tracer_provider
-        httpx.Client = _InstrumentedClient
+        # Intentionally using a private attribute here, see:
+        # https://github.com/open-telemetry/opentelemetry-python-contrib/pull/2538#discussion_r1610603719
+        httpx.Client = httpx._api.Client = _InstrumentedClient
         httpx.AsyncClient = _InstrumentedAsyncClient
 
     def _uninstrument(self, **kwargs):
-        httpx.Client = self._original_client
+        httpx.Client = httpx._api.Client = self._original_client
         httpx.AsyncClient = self._original_async_client
         _InstrumentedClient._tracer_provider = None
         _InstrumentedClient._request_hook = None

instrumentation/opentelemetry-instrumentation-httpx/tests/test_httpx_integration.py

@@ -532,12 +532,36 @@ def test_instrument_client(self):
             self.assertEqual(result.text, "Hello!")
             self.assert_span(num_spans=1)
 
+        def test_instrumentation_without_client(self):
+
+            HTTPXClientInstrumentor().instrument()
+            results = [
+                httpx.get(self.URL),
+                httpx.request("GET", self.URL),
+            ]
+            with httpx.stream("GET", self.URL) as stream:
+                stream.read()
+                results.append(stream)
+
+            spans = self.assert_span(num_spans=len(results))
+            for idx, res in enumerate(results):
+                with self.subTest(idx=idx, res=res):
+                    self.assertEqual(res.text, "Hello!")
+                    self.assertEqual(
+                        spans[idx].attributes[SpanAttributes.HTTP_URL],
+                        self.URL,
+                    )
+
+            HTTPXClientInstrumentor().uninstrument()
+
         def test_uninstrument(self):
             HTTPXClientInstrumentor().instrument()
             HTTPXClientInstrumentor().uninstrument()
             client = self.create_client()
             result = self.perform_request(self.URL, client=client)
+            result_no_client = httpx.get(self.URL)
             self.assertEqual(result.text, "Hello!")
+            self.assertEqual(result_no_client.text, "Hello!")
             self.assert_span(num_spans=0)
 
         def test_uninstrument_client(self):