How can I add a client interceptor manually?

[jenstroeger]

Adding a server interceptor manually is documented here and it seems to work.

Adding a client interceptor manually is not documented, and trying the server pattern fails:

channel = grpc.insecure_channel(f"localhost:50051")
channel = grpc.intercept_channel(
    channel, opentelemetry.instrumentation.grpc.client_interceptor()  # type: ignore[no-untyped-call]
)

with

TypeError: interceptor must be grpc.UnaryUnaryClientInterceptor or grpc.UnaryStreamClientInterceptor or grpc.StreamUnaryClientInterceptor or grpc.StreamStreamClientInterceptor or

as documented here.

Looking through the code, the client_interceptor() returns a OpenTelemetryClientInterceptor instance that inherits from custom OpenTelemetry ABCs — hence the error message.

However, there’s also a opentelemetry.instrumentation.grpc.intercept_channel() function which I couldn’t find documented but seems to work:

channel = grpc.insecure_channel(f"localhost:50051")
channel = opentelemetry.instrumentation.grpc.intercept_channel(
    channel, opentelemetry.instrumentation.grpc.client_interceptor()  # type: ignore[no-untyped-call]
)

Furthermore, considering that the channel returned by the custom OpenTelemetry intercept_channel() is also a context manager (like gRPC’s Channel is), should both be considered, i.e.

import opentelemetry.instrumentation.grpc as optegrpc

with grpc.insecure_channel(f"localhost:50051") as channel:
    with optegrpc.intercept_channel(channel, optegrpc.client_interceptor()) as opte_channel:
        stub = SomeStub(opte_channel)
        ...

So my question is: what’s the general recommendation — use the GrpcInstrumentorServer() and GrpcInstrumentorClient() on a module level (better yet, the package’s top-level to ensure instrumentation is installed exactly once), or manual instrumentation? And how does the custom intercept_channel() function work with normal interceptors that don’t inherit from OpenTelementry’s ABCs (I’ve not tried).

Cheers!