feat: drop the ASGI send/receive spans from traces (#86)

Sets opentelemetry_exclude_spans=["receive", "send"], so a traced request
records its server span and database spans only.

Author: lesnik512

app/settings.py

@@ -41,6 +41,7 @@ def api_bootstrapper_config(self) -> FastAPIConfig:
             service_environment=self.service_environment,
             service_debug=self.service_debug,
             opentelemetry_endpoint=self.opentelemetry_endpoint,
+            opentelemetry_exclude_spans=["receive", "send"],
             sentry_dsn=self.sentry_dsn,
             cors_allowed_origins=self.cors_allowed_origins,
             cors_allowed_methods=self.cors_allowed_methods,

readme.md

@@ -41,6 +41,8 @@ OTEL_TRACES_SAMPLER_ARG=0.1
 
 This keeps one trace in ten, and follows the caller's decision when a request arrives with a trace context. Errors still reach Sentry when `SENTRY_DSN` is set.
 
+The template also turns off the ASGI `send` and `receive` spans (`opentelemetry_exclude_spans` in `app/settings.py`), so each request records its server span and database spans only. With every request traced, that raised throughput by 5 to 8% in the same benchmark. Remove the setting if you need those spans.
+
 ## 📝 [License](https://github.com/modern-python/fastapi-sqlalchemy-template/blob/main/LICENSE)
 
 ## Part of `modern-python`

tests/test_tracing.py

@@ -5,9 +5,10 @@
 from fastapi import status
 from httpx import ASGITransport, AsyncClient
 from opentelemetry import trace
-from opentelemetry.sdk.trace import TracerProvider
+from opentelemetry.sdk.trace import ReadableSpan, TracerProvider
 from opentelemetry.sdk.trace.export import SimpleSpanProcessor
 from opentelemetry.sdk.trace.export.in_memory_span_exporter import InMemorySpanExporter
+from opentelemetry.trace import SpanKind
 
 from app.application import build_app
 from app.settings import Settings, settings
@@ -17,7 +18,7 @@
     import pytest
 
 
-async def test_db_queries_produce_sqlalchemy_spans(monkeypatch: pytest.MonkeyPatch) -> None:
+async def _trace_list_decks(monkeypatch: pytest.MonkeyPatch) -> tuple[ReadableSpan, ...]:
     traced_config = dataclasses.replace(settings.api_bootstrapper_config, opentelemetry_log_traces=True)
     monkeypatch.setattr(Settings, "api_bootstrapper_config", traced_config)
     exporter = InMemorySpanExporter()
@@ -30,12 +31,26 @@ async def test_db_queries_produce_sqlalchemy_spans(monkeypatch: pytest.MonkeyPat
         response = await client.get("/api/decks/")
 
     assert response.status_code == status.HTTP_200_OK
+    return exporter.get_finished_spans()
+
+
+async def test_db_queries_produce_sqlalchemy_spans(monkeypatch: pytest.MonkeyPatch) -> None:
     db_spans = [
         span
-        for span in exporter.get_finished_spans()
+        for span in await _trace_list_decks(monkeypatch)
         if span.instrumentation_scope is not None
         and span.instrumentation_scope.name == "opentelemetry.instrumentation.sqlalchemy"
         and span.name.startswith("SELECT")
     ]
     assert db_spans
     assert all(span.parent is not None for span in db_spans)
+
+
+async def test_request_has_no_asgi_event_spans(monkeypatch: pytest.MonkeyPatch) -> None:
+    request_spans = [
+        span
+        for span in await _trace_list_decks(monkeypatch)
+        if span.instrumentation_scope is None
+        or span.instrumentation_scope.name != "opentelemetry.instrumentation.sqlalchemy"
+    ]
+    assert [span.kind for span in request_spans] == [SpanKind.SERVER]