Add fields property

.github/workflows/test.yml

@@ -10,7 +10,7 @@ env:
   # Otherwise, set variable to the commit of your branch on
   # opentelemetry-python-contrib which is compatible with these Core repo
   # changes.
-  CONTRIB_REPO_SHA: bcec49cf2eccf8da66c9e63b9836ea8a20516efc
+  CONTRIB_REPO_SHA: e1d4eeb951694afebb1767b4ea8f593753d894e3
 
 jobs:
   build:

opentelemetry-api/CHANGELOG.md

@@ -2,6 +2,8 @@
 
 ## Unreleased
 
+- Add `fields` to propagators ([#1374](https://github.com/open-telemetry/opentelemetry-python/pull/1374))
+
 ## Version 0.16b0
 
 Released 2020-11-25

opentelemetry-api/src/opentelemetry/baggage/propagation/__init__.py

@@ -87,6 +87,11 @@ def inject(
         baggage_string = _format_baggage(baggage_entries)
         set_in_carrier(carrier, self._BAGGAGE_HEADER_NAME, baggage_string)
 
+    @property
+    def fields(self) -> typing.Set[str]:
+        """Returns a set with the fields set in `inject`."""
+        return {self._BAGGAGE_HEADER_NAME}
+
 
 def _format_baggage(baggage_entries: typing.Mapping[str, object]) -> str:
     return ",".join(

opentelemetry-api/src/opentelemetry/propagators/composite.py

@@ -65,3 +65,18 @@ def inject(
         """
         for propagator in self._propagators:
             propagator.inject(set_in_carrier, carrier, context)
+
+    @property
+    def fields(self) -> typing.Set[str]:
+        """Returns a set with the fields set in `inject`.
+
+        See
+        `opentelemetry.trace.propagation.textmap.TextMapPropagator.fields`
+        """
+        composite_fields = set()
+
+        for propagator in self._propagators:
+            for field in propagator.fields:
+                composite_fields.add(field)
+
+        return composite_fields

opentelemetry-api/src/opentelemetry/trace/propagation/textmap.py

@@ -129,3 +129,16 @@ def inject(
                 context if not set.
 
         """
+
+    @property
+    @abc.abstractmethod
+    def fields(self) -> typing.Set[str]:
+        """
+        Gets the fields set in the carrier by the `inject` method.
+
+        If the carrier is reused, its fields that correspond with the ones
+        present in this attribute should be deleted before calling `inject`.
+
+        Returns:
+            A set with the fields set in `inject`.
+        """

opentelemetry-api/src/opentelemetry/trace/propagation/tracecontext.py

@@ -132,6 +132,15 @@ def inject(
                 carrier, self._TRACESTATE_HEADER_NAME, tracestate_string
             )
 
+    @property
+    def fields(self) -> typing.Set[str]:
+        """Returns a set with the fields set in `inject`.
+
+        See
+        `opentelemetry.trace.propagation.textmap.TextMapPropagator.fields`
+        """
+        return {self._TRACEPARENT_HEADER_NAME, self._TRACESTATE_HEADER_NAME}
+
 
 def _parse_tracestate(header_list: typing.List[str]) -> trace.TraceState:
     """Parse one or more w3c tracestate header into a TraceState.

opentelemetry-api/tests/baggage/test_baggage_propagation.py

@@ -12,8 +12,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 #
-import typing
 import unittest
+from unittest.mock import Mock, patch
 
 from opentelemetry import baggage
 from opentelemetry.baggage.propagation import BaggagePropagator
@@ -142,3 +142,18 @@ def test_inject_non_string_values(self):
         self.assertIn("key1=True", output)
         self.assertIn("key2=123", output)
         self.assertIn("key3=123.567", output)
+
+    @patch("opentelemetry.baggage.propagation.baggage")
+    @patch("opentelemetry.baggage.propagation._format_baggage")
+    def test_fields(self, mock_format_baggage, mock_baggage):
+
+        mock_set_in_carrier = Mock()
+
+        self.propagator.inject(mock_set_in_carrier, {})
+
+        inject_fields = set()
+
+        for mock_call in mock_set_in_carrier.mock_calls:
+            inject_fields.add(mock_call[1][1])
+
+        self.assertEqual(inject_fields, self.propagator.fields)

opentelemetry-api/tests/propagators/test_composite.py

@@ -26,6 +26,8 @@ def get_as_list(dict_object, key):
 def mock_inject(name, value="data"):
     def wrapped(setter, carrier=None, context=None):
         carrier[name] = value
+        setter({}, "inject_field_{}_0".format(name), None)
+        setter({}, "inject_field_{}_1".format(name), None)
 
     return wrapped
 
@@ -39,18 +41,27 @@ def wrapped(getter, carrier=None, context=None):
     return wrapped
 
 
+def mock_fields(name):
+    return {"inject_field_{}_0".format(name), "inject_field_{}_1".format(name)}
+
+
 class TestCompositePropagator(unittest.TestCase):
     @classmethod
     def setUpClass(cls):
         cls.mock_propagator_0 = Mock(
-            inject=mock_inject("mock-0"), extract=mock_extract("mock-0")
+            inject=mock_inject("mock-0"),
+            extract=mock_extract("mock-0"),
+            fields=mock_fields("mock-0"),
         )
         cls.mock_propagator_1 = Mock(
-            inject=mock_inject("mock-1"), extract=mock_extract("mock-1")
+            inject=mock_inject("mock-1"),
+            extract=mock_extract("mock-1"),
+            fields=mock_fields("mock-1"),
         )
         cls.mock_propagator_2 = Mock(
             inject=mock_inject("mock-0", value="data2"),
             extract=mock_extract("mock-0", value="context2"),
+            fields=mock_fields("mock-0"),
         )
 
     def test_no_propagators(self):
@@ -105,3 +116,23 @@ def test_multiple_propagators_same_key(self):
             get_as_list, carrier=new_carrier, context={}
         )
         self.assertEqual(context, {"mock-0": "context2"})
+
+    def test_fields(self):
+        propagator = CompositeHTTPPropagator(
+            [
+                self.mock_propagator_0,
+                self.mock_propagator_1,
+                self.mock_propagator_2,
+            ]
+        )
+
+        mock_set_in_carrier = Mock()
+
+        propagator.inject(mock_set_in_carrier, {})
+
+        inject_fields = set()
+
+        for mock_call in mock_set_in_carrier.mock_calls:
+            inject_fields.add(mock_call[1][1])
+
+        self.assertEqual(inject_fields, propagator.fields)

opentelemetry-api/tests/trace/propagation/test_tracecontexthttptextformat.py

@@ -14,6 +14,7 @@
 
 import typing
 import unittest
+from unittest.mock import Mock, patch
 
 from opentelemetry import trace
 from opentelemetry.trace.propagation import tracecontext
@@ -232,7 +233,8 @@ def test_tracestate_keys(self):
                 carrier_getter,
                 {
                     "traceparent": [
-                        "00-12345678901234567890123456789012-1234567890123456-00"
+                        "00-12345678901234567890123456789012-"
+                        "1234567890123456-00"
                     ],
                     "tracestate": [tracestate_value],
                 },
@@ -248,3 +250,33 @@ def test_tracestate_keys(self):
         self.assertEqual(
             span.get_span_context().trace_state["foo-_*/bar"], "bar4"
         )
+
+    @patch("opentelemetry.trace.INVALID_SPAN_CONTEXT")
+    @patch("opentelemetry.trace.get_current_span")
+    def test_fields(self, mock_get_current_span, mock_invalid_span_context):
+
+        mock_get_current_span.configure_mock(
+            return_value=Mock(
+                **{
+                    "get_span_context.return_value": Mock(
+                        **{
+                            "trace_id": 1,
+                            "span_id": 2,
+                            "trace_flags": 3,
+                            "trace_state": {"a": "b"},
+                        }
+                    )
+                }
+            )
+        )
+
+        mock_set_in_carrier = Mock()
+
+        FORMAT.inject(mock_set_in_carrier, {})
+
+        inject_fields = set()
+
+        for mock_call in mock_set_in_carrier.mock_calls:
+            inject_fields.add(mock_call[1][1])
+
+        self.assertEqual(inject_fields, FORMAT.fields)

opentelemetry-sdk/CHANGELOG.md

@@ -4,6 +4,8 @@
 
 - Add meter reference to observers
   ([#1425](https://github.com/open-telemetry/opentelemetry-python/pull/1425))
+- Add `fields` to propagators
+  ([#1374](https://github.com/open-telemetry/opentelemetry-python/pull/1374))
 
 ## Version 0.16b0
 

opentelemetry-sdk/src/opentelemetry/sdk/trace/propagation/b3_format.py

@@ -152,6 +152,15 @@ def inject(
             )
         set_in_carrier(carrier, self.SAMPLED_KEY, "1" if sampled else "0")
 
+    @property
+    def fields(self) -> typing.Set[str]:
+        return {
+            self.TRACE_ID_KEY,
+            self.SPAN_ID_KEY,
+            self.PARENT_SPAN_ID_KEY,
+            self.SAMPLED_KEY,
+        }
+
 
 def format_trace_id(trace_id: int) -> str:
     """Format the trace id according to b3 specification."""

opentelemetry-sdk/tests/trace/propagation/test_b3_format.py

@@ -13,7 +13,7 @@
 # limitations under the License.
 
 import unittest
-from unittest.mock import patch
+from unittest.mock import Mock, patch
 
 import opentelemetry.sdk.trace as trace
 import opentelemetry.sdk.trace.propagation.b3_format as b3_format
@@ -337,3 +337,21 @@ def setter(carrier, key, value):
 
         ctx = FORMAT.extract(CarrierGetter(), {})
         FORMAT.inject(setter, {}, ctx)
+
+    def test_fields(self):
+        """Make sure the fields attribute returns the fields used in inject"""
+
+        tracer = trace.TracerProvider().get_tracer("sdk_tracer_provider")
+
+        mock_set_in_carrier = Mock()
+
+        with tracer.start_as_current_span("parent"):
+            with tracer.start_as_current_span("child"):
+                FORMAT.inject(mock_set_in_carrier, {})
+
+        inject_fields = set()
+
+        for call in mock_set_in_carrier.mock_calls:
+            inject_fields.add(call[1][1])
+
+        self.assertEqual(FORMAT.fields, inject_fields)

tests/util/src/opentelemetry/test/mock_textmap.py

@@ -47,6 +47,10 @@ def inject(
     ) -> None:
         return None
 
+    @property
+    def fields(self):
+        return set()
+
 
 class MockTextMapPropagator(TextMapPropagator):
     """Mock propagator for testing purposes."""
@@ -89,3 +93,7 @@ def inject(
         set_in_carrier(
             carrier, self.SPAN_ID_KEY, str(span.get_span_context().span_id)
         )
+
+    @property
+    def fields(self):
+        return {self.TRACE_ID_KEY, self.SPAN_ID_KEY}