Reject commas in FastAPI and FastMCP tracing exclusions

docs/introduction/configuration.md

@@ -223,7 +223,7 @@ Additional parameters:
   health-check path. While it is `False`, OpenTelemetry's HTTP metrics also leave health-check
   requests out, because the instrumentation skips an excluded URL entirely. Set it to `True` to
   trace probes, for example to watch their latency.
-- `opentelemetry_excluded_urls` - extra regexes for URLs excluded from tracing; the metrics path and (unless health-check spans are enabled) the health-check path are excluded automatically. Litestar searches them in the request path, FastAPI and FastMCP in the full URL. The environment variable OpenTelemetry defines for the framework (`OTEL_PYTHON_LITESTAR_EXCLUDED_URLS`, `OTEL_PYTHON_FASTAPI_EXCLUDED_URLS` or `OTEL_PYTHON_STARLETTE_EXCLUDED_URLS` for FastMCP), falling back to `OTEL_PYTHON_EXCLUDED_URLS`, adds to them.
+- `opentelemetry_excluded_urls` - extra regexes for URLs excluded from tracing; the metrics path and (unless health-check spans are enabled) the health-check path are excluded automatically. Litestar searches them in the request path, FastAPI and FastMCP in the full URL. FastAPI and FastMCP raise `ConfigurationError` at config construction if an entry contains a comma because OpenTelemetry uses commas to separate patterns. Litestar accepts commas in config entries. The environment variable OpenTelemetry defines for the framework (`OTEL_PYTHON_LITESTAR_EXCLUDED_URLS`, `OTEL_PYTHON_FASTAPI_EXCLUDED_URLS` or `OTEL_PYTHON_STARLETTE_EXCLUDED_URLS` for FastMCP), falling back to `OTEL_PYTHON_EXCLUDED_URLS`, adds to them.
 - `opentelemetry_metrics_endpoint` - will be passed to `OTLPMetricExporter` as endpoint, and turns on the metrics signal. Its own field rather than a flag on `opentelemetry_endpoint`, so upgrading never starts exporting metrics you did not ask for. Under `opentelemetry_exporter_protocol="http"` this is a full URL (e.g. `http://collector:4318/v1/metrics`); `opentelemetry_exporter_protocol` and `opentelemetry_insecure` are shared with traces.
 
 ### Metrics

lite_bootstrap/bootstrappers/fastapi_bootstrapper.py

@@ -79,6 +79,7 @@ class FastAPIConfig(
     prometheus_instrument_additional_params: dict[str, typing.Any] = dataclasses.field(default_factory=dict)
     prometheus_expose_additional_params: dict[str, typing.Any] = dataclasses.field(default_factory=dict)
     logging_access_log_enabled: bool = False
+    _opentelemetry_exclusions_use_comma_separator: typing.ClassVar[bool] = True
     _sentry_lean_replaced_integrations: typing.ClassVar[Mapping[str, str]] = {
         "starlette": "StarletteIntegration",
         "fastapi": "FastApiIntegration",

lite_bootstrap/bootstrappers/fastmcp_bootstrapper.py

@@ -197,6 +197,7 @@ class FastMcpConfig(
     fastmcp_prometheus_tool_metrics_enabled: bool = True
     prometheus_instrumentator_additional_params: dict[str, typing.Any] = dataclasses.field(default_factory=dict)
     prometheus_instrument_additional_params: dict[str, typing.Any] = dataclasses.field(default_factory=dict)
+    _opentelemetry_exclusions_use_comma_separator: typing.ClassVar[bool] = True
     _sentry_lean_replaced_integrations: typing.ClassVar[Mapping[str, str]] = {"starlette": "StarletteIntegration"}
 
 

lite_bootstrap/instruments/opentelemetry_instrument.py

@@ -5,7 +5,7 @@
 import urllib.parse
 
 from lite_bootstrap import import_checker
-from lite_bootstrap.exceptions import InstrumentDependencyMissingWarning, collect_teardown_errors
+from lite_bootstrap.exceptions import ConfigurationError, InstrumentDependencyMissingWarning, collect_teardown_errors
 from lite_bootstrap.helpers.warn import warn_at_caller
 from lite_bootstrap.instruments.base import BaseConfig, BaseInstrument
 
@@ -137,6 +137,16 @@ class OpenTelemetryAsgiConfig(OpenTelemetryConfig):
         default_factory=lambda: ["receive", "send"]
     )
 
+    _opentelemetry_exclusions_use_comma_separator: typing.ClassVar[bool] = False
+
+    def __post_init__(self) -> None:
+        super().__post_init__()
+        if self._opentelemetry_exclusions_use_comma_separator:
+            for pattern in self.opentelemetry_excluded_urls:
+                if "," in pattern:
+                    msg = f"opentelemetry_excluded_urls entry {pattern!r} contains a comma, which separates patterns"
+                    raise ConfigurationError(msg)
+
 
 if import_checker.is_opentelemetry_sdk_installed and import_checker.is_pyroscope_installed:
     _OTEL_PROFILE_ID_KEY: typing.Final = "pyroscope.profile.id"

tests/test_fastapi_bootstrap.py

@@ -2,6 +2,7 @@
 import dataclasses
 import json
 import logging
+import re
 import typing
 import uuid
 import warnings
@@ -20,7 +21,7 @@
 from starlette import status
 from starlette.testclient import TestClient
 
-from lite_bootstrap import FastAPIBootstrapper, FastAPIConfig, import_checker
+from lite_bootstrap import FastAPIBootstrapper, FastAPIConfig, FastMcpConfig, import_checker
 from lite_bootstrap.bootstrappers import fastapi_bootstrapper
 from lite_bootstrap.exceptions import ConfigurationError, InstrumentDependencyMissingWarning
 from lite_bootstrap.instruments.healthchecks_instrument import HealthProbe
@@ -45,6 +46,15 @@
 std_logger = logging.getLogger()
 
 
+@pytest.mark.parametrize("config_class", [FastAPIConfig, FastMcpConfig])
+def test_config_rejects_comma_in_opentelemetry_excluded_url(
+    config_class: type[FastAPIConfig] | type[FastMcpConfig],
+) -> None:
+    pattern = r"/v\d{1,2}/ping$"
+    with pytest.raises(ConfigurationError, match=re.escape(repr(pattern))):
+        config_class(opentelemetry_excluded_urls=[pattern])
+
+
 @pytest.fixture
 def fastapi_config() -> FastAPIConfig:
     return FastAPIConfig(

tests/test_litestar_bootstrap.py

@@ -611,7 +611,7 @@ async def get_item(item_id: int) -> dict[str, int]:
     config = dataclasses.replace(
         litestar_config,
         application_config=AppConfig(route_handlers=[get_item]),
-        opentelemetry_excluded_urls=[r"/items/\d+$"],
+        opentelemetry_excluded_urls=[r"/items/\d{1,2}$"],
     )
     application = LitestarBootstrapper(bootstrap_config=config).bootstrap()