Propagator Class [POC for review]

ext/opentelemetry-ext-http-requests/src/opentelemetry/ext/http_requests/__init__.py

@@ -22,6 +22,8 @@
 
 from requests.sessions import Session
 
+from opentelemetry import propagator
+
 
 # NOTE: Currently we force passing a tracer. But in turn, this forces the user
 # to configure a SDK before enabling this integration. In turn, this means that
@@ -77,6 +79,10 @@ def instrumented_request(self, method, url, *args, **kwargs):
             span.set_attribute("http.status_code", result.status_code)
             span.set_attribute("http.status_text", result.reason)
 
+            propagator.global_propagator().inject(
+                result.headers.__setitem__, result.headers
+            )
+
             return result
 
         # TODO: How to handle exceptions? Should we create events for them? Set

ext/opentelemetry-ext-http-requests/tests/test_requests_integration.py

@@ -2,16 +2,19 @@
 import unittest
 from unittest import mock
 
-import opentelemetry.ext.http_requests
 import requests
 import urllib3
-from opentelemetry import trace
+
+import opentelemetry.ext.http_requests
+from opentelemetry import propagator, trace
+from opentelemetry.context import Context
 
 
 class TestRequestsIntegration(unittest.TestCase):
 
     # TODO: Copy & paste from test_wsgi_middleware
     def setUp(self):
+        propagator.set_propagator(propagator.Propagator(Context, None, None))
         self.span_attrs = {}
         self.tracer = trace.tracer()
         self.span_context_manager = mock.MagicMock()

opentelemetry-api/src/opentelemetry/context/__init__.py

@@ -11,8 +11,6 @@
 # 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.
-
-
 """
 The OpenTelemetry context module provides abstraction layer on top of
 thread-local storage and contextvars. The long term direction is to switch to
@@ -27,9 +25,8 @@
     >>> Context.foo
     2
 
-When explicit thread is used, a helper function
-``Context.with_current_context`` can be used to carry the context across
-threads::
+When explicit thread is used, a helper function `BaseRuntimeContext.with_current_context`
+can be used to carry the context across threads::
 
     from threading import Thread
     from opentelemetry.context import Context
@@ -138,20 +135,26 @@ async def main():
         asyncio.run(main())
 """
 
-import typing
-
 from .base_context import BaseRuntimeContext
 
 __all__ = ["Context"]
 
 
-Context = None  # type: typing.Optional[BaseRuntimeContext]
+def create_context() -> BaseRuntimeContext:
+    """Create a new context object.
+
+    Return a new RuntimeContext, instantiating the variant that
+    is the most appropriate for the version of Python being used.
+    """
+
+    try:
+        from .async_context import AsyncRuntimeContext
+
+        return AsyncRuntimeContext()
+    except ImportError:
+        from .thread_local_context import ThreadLocalRuntimeContext
 
-try:
-    from .async_context import AsyncRuntimeContext
+        return ThreadLocalRuntimeContext()
 
-    Context = AsyncRuntimeContext()
-except ImportError:
-    from .thread_local_context import ThreadLocalRuntimeContext
 
-    Context = ThreadLocalRuntimeContext()
+Context = create_context()