Add links to modack spans in subscribe span

google/cloud/pubsub_v1/subscriber/_protocol/streaming_pull_manager.py

@@ -1032,6 +1032,7 @@ def _send_lease_modacks(
         modack_span: Optional[trace.Span] = None
         if self._client.open_telemetry_enabled:
             subscribe_span_links: List[trace.Link] = []
+            subscribe_spans: List[trace.Span] = []
             assert len(self._subscription.split("/")) == 4
             subscription_id: str = self._subscription.split("/")[3]
             project_id: str = self._subscription.split("/")[1]
@@ -1044,6 +1045,7 @@ def _send_lease_modacks(
                     subscribe_span_links.append(
                         trace.Link(subscribe_span.get_span_context())
                     )
+                    subscribe_spans.append(subscribe_span)
             modack_span = start_modack_span(
                 subscribe_span_links,
                 subscription_id,
@@ -1053,6 +1055,17 @@ def _send_lease_modacks(
                 "_send_lease_modacks",
                 receipt_modack,
             )
+            if (
+                modack_span and modack_span.get_span_context().trace_flags.sampled
+            ):  # pragma: NO COVER
+                modack_span_context: trace.SpanContext = modack_span.get_span_context()
+                for subscribe_span in subscribe_spans:
+                    subscribe_span.add_link(
+                        context=modack_span_context,
+                        attributes={
+                            "messaging.operation.name": "modack",
+                        },
+                    )
 
         with self._exactly_once_enabled_lock:
             exactly_once_enabled = self._exactly_once_enabled

tests/unit/pubsub_v1/subscriber/test_streaming_pull_manager.py

@@ -632,6 +632,10 @@ def test__maybe_release_messages_negative_on_hold_bytes_warning(caplog):
     assert manager._on_hold_bytes == 0  # should be auto-corrected
 
 
+@pytest.mark.skipif(
+    sys.version_info < (3, 8),
+    reason="Open Telemetry not supported below Python version 3.8",
+)
 @pytest.mark.parametrize(
     "receipt_modack",
     [
@@ -683,6 +687,11 @@ def test_opentelemetry__send_lease_modacks(span_exporter, receipt_modack):
     assert len(subscribe_span1.events) == 0
     assert len(subscribe_span2.events) == 0
 
+    assert len(subscribe_span1.links) == 0
+    assert len(subscribe_span2.links) == 1
+    assert subscribe_span2.links[0].context == modack_span.context
+    assert subscribe_span2.links[0].attributes["messaging.operation.name"] == "modack"
+
     assert modack_span.name == "subscriptionID modack"
     assert modack_span.parent is None
     assert modack_span.kind == trace.SpanKind.CLIENT