fix(grpc): Derive interception state from channel fields (#5302)

Detect existing `ClientInterceptor` by inspecting `grpc.Channel`.

Replace integration-level flag with a helper that walks the `grpc.Channel` object to determine if an instance of `ClientInterceptor` has already been attached.

Closes #5183

Author: alexander-alderman-webb

sentry_sdk/integrations/grpc/__init__.py

@@ -50,14 +50,29 @@ def __getitem__(self, _):
 GRPC_VERSION = parse_version(grpc.__version__)
 
 
+def _is_channel_intercepted(channel: "Channel") -> bool:
+    interceptor = getattr(channel, "_interceptor", None)
+    while interceptor is not None:
+        if isinstance(interceptor, ClientInterceptor):
+            return True
+
+        inner_channel = getattr(channel, "_channel", None)
+        if inner_channel is None:
+            return False
+
+        channel = inner_channel
+        interceptor = getattr(channel, "_interceptor", None)
+
+    return False
+
+
 def _wrap_channel_sync(func: "Callable[P, Channel]") -> "Callable[P, Channel]":
     "Wrapper for synchronous secure and insecure channel."
 
     @wraps(func)
     def patched_channel(*args: "Any", **kwargs: "Any") -> "Channel":
         channel = func(*args, **kwargs)
-        if not ClientInterceptor._is_intercepted:
-            ClientInterceptor._is_intercepted = True
+        if not _is_channel_intercepted(channel):
             return intercept_channel(channel, ClientInterceptor())
         else:
             return channel
@@ -70,7 +85,7 @@ def _wrap_intercept_channel(func: "Callable[P, Channel]") -> "Callable[P, Channe
     def patched_intercept_channel(
         channel: "Channel", *interceptors: "grpc.ServerInterceptor"
     ) -> "Channel":
-        if ClientInterceptor._is_intercepted:
+        if _is_channel_intercepted(channel):
             interceptors = tuple(
                 [
                     interceptor

sentry_sdk/integrations/grpc/client.py

@@ -22,8 +22,6 @@ class ClientInterceptor(
     grpc.UnaryUnaryClientInterceptor,  # type: ignore
     grpc.UnaryStreamClientInterceptor,  # type: ignore
 ):
-    _is_intercepted = False
-
     def intercept_unary_unary(
         self: "ClientInterceptor",
         continuation: "Callable[[ClientCallDetails, Message], _UnaryOutcome]",

tests/integrations/grpc/test_grpc.py

@@ -8,6 +8,7 @@
 from sentry_sdk import start_span, start_transaction
 from sentry_sdk.consts import OP
 from sentry_sdk.integrations.grpc import GRPCIntegration
+from sentry_sdk.integrations.grpc.client import ClientInterceptor
 from tests.conftest import ApproxDict
 from tests.integrations.grpc.grpc_test_service_pb2 import gRPCTestMessage
 from tests.integrations.grpc.grpc_test_service_pb2_grpc import (
@@ -269,6 +270,42 @@ def test_grpc_client_other_interceptor(sentry_init, capture_events_forksafe):
     )
 
 
+@pytest.mark.forked
+def test_prevent_dual_client_interceptor(sentry_init, capture_events_forksafe):
+    sentry_init(traces_sample_rate=1.0, integrations=[GRPCIntegration()])
+    events = capture_events_forksafe()
+
+    server, channel = _set_up()
+
+    # Intercept the channel
+    channel = grpc.intercept_channel(channel, ClientInterceptor())
+    stub = gRPCTestServiceStub(channel)
+
+    with start_transaction():
+        stub.TestServe(gRPCTestMessage(text="test"))
+
+    _tear_down(server=server)
+
+    events.write_file.close()
+    events.read_event()
+    local_transaction = events.read_event()
+    span = local_transaction["spans"][0]
+
+    assert len(local_transaction["spans"]) == 1
+    assert span["op"] == OP.GRPC_CLIENT
+    assert (
+        span["description"]
+        == "unary unary call to /grpc_test_server.gRPCTestService/TestServe"
+    )
+    assert span["data"] == ApproxDict(
+        {
+            "type": "unary unary",
+            "method": "/grpc_test_server.gRPCTestService/TestServe",
+            "code": "OK",
+        }
+    )
+
+
 @pytest.mark.forked
 def test_grpc_client_and_servers_interceptors_integration(
     sentry_init, capture_events_forksafe