Materialize scoped baggage on current span

README.md

@@ -463,6 +463,22 @@ Parameters description:
 
 These settings are subsequently passed to [opentelemetry](https://opentelemetry.io/), finalizing your Opentelemetry integration.
 
+If an authoritative baggage value becomes available only after the current span has started, pass the same mapping to
+`opentelemetry_baggage_scope` to also materialize that value on the already-started span:
+
+```python
+from microbootstrap import opentelemetry_baggage_scope
+
+
+with opentelemetry_baggage_scope(
+ {"conversation_id": conversation_id},
+ current_span_attributes=settings.opentelemetry_baggage_span_attributes,
+):
+ ...
+```
+
+Only non-`None` baggage values supplied to the scope and present in the mapping are added to a recording current span.
+
 #### FastStream
 
 For FastStream you also should pass `opentelemetry_middleware_cls` - OpenTelemetry middleware for your broker

microbootstrap/instruments/opentelemetry_instrument.py

@@ -17,7 +17,7 @@
 from opentelemetry.sdk.trace import TracerProvider as SdkTracerProvider
 from opentelemetry.sdk.trace.export import BatchSpanProcessor, ConsoleSpanExporter, SimpleSpanProcessor
 from opentelemetry.semconv.resource import ResourceAttributes
-from opentelemetry.trace import SpanKind, format_span_id, set_tracer_provider
+from opentelemetry.trace import SpanKind, format_span_id, get_current_span, set_tracer_provider
 from opentelemetry.util._importlib_metadata import entry_points
 
 from microbootstrap.instruments.base import BaseInstrumentConfig, Instrument
@@ -44,6 +44,8 @@
 @contextlib.contextmanager
 def opentelemetry_baggage_scope(
  baggage_values: typing.Mapping[str, object | None],
+ *,
+ current_span_attributes: typing.Mapping[str, str] | None = None,
 ) -> typing.Iterator[None]:
  baggage_context = context.get_current()
  for key, value in baggage_values.items():
@@ -55,6 +57,10 @@ def opentelemetry_baggage_scope(
 
  token: typing.Final = context.attach(baggage_context)
  try:
+ if current_span_attributes and (current_span := get_current_span()).is_recording():
+ for baggage_key, span_attribute in current_span_attributes.items():
+ if baggage_key in baggage_values and (value := baggage_values[baggage_key]) is not None:
+ current_span.set_attribute(span_attribute, str(value))
  yield
  except Exception as exc:
  with contextlib.suppress(Exception):

tests/instruments/test_opentelemetry.py

@@ -64,6 +64,51 @@ def test_opentelemetry_baggage_scope_does_not_replace_exception_when_snapshot_fa
  raise ValueError("application error")
 
 
+def test_opentelemetry_baggage_scope_materializes_supplied_values_on_current_span(
+ monkeypatch: pytest.MonkeyPatch,
+) -> None:
+ conversation_id = 42
+ current_span = MagicMock(spec=Span)
+ current_span.is_recording.return_value = True
+ monkeypatch.setattr(opentelemetry_instrument, "get_current_span", Mock(return_value=current_span))
+
+ with opentelemetry_baggage_scope(
+ {"conversation_id": conversation_id, "not_configured": "ignored"},
+ current_span_attributes={
+ "conversation_id": "conversation.id",
+ "not_supplied": "not.supplied",
+ },
+ ):
+ assert baggage.get_baggage("conversation_id") == conversation_id
+
+ current_span.set_attribute.assert_called_once_with("conversation.id", str(conversation_id))
+
+
+@pytest.mark.parametrize(
+ ("baggage_value", "is_recording"),
+ [
+ (None, True),
+ ("conversation-1", False),
+ ],
+)
+def test_opentelemetry_baggage_scope_skips_current_span_attribute(
+ baggage_value: str | None,
+ is_recording: bool,
+ monkeypatch: pytest.MonkeyPatch,
+) -> None:
+ current_span = MagicMock(spec=Span)
+ current_span.is_recording.return_value = is_recording
+ monkeypatch.setattr(opentelemetry_instrument, "get_current_span", Mock(return_value=current_span))
+
+ with opentelemetry_baggage_scope(
+ {"conversation_id": baggage_value},
+ current_span_attributes={"conversation_id": "conversation.id"},
+ ):
+ pass
+
+ current_span.set_attribute.assert_not_called()
+
+
 @pytest.mark.parametrize(
  ("span_kind", "expected_attribute"),
  [