Field output.headers not being sent as Trailers if output.code != 0

[danieljph]

Hi guys,

Background:
I need to mock an external gRPC server that currently returns an error-code & error-message in Metadata (Trailers) when gRPC status != 0.

I try to simulate that using this stub:

{
    "service": "TransferService",
    "method": "direct",
    "input": {
        "matches": {
            "code": ".*"
        }
    },
    "output": {
        "code": 10,
        "headers": {
            "code": "EXTERNAL_SERVICE_ERROR_CODE",
            "message": "External service error message"
        },
        "error": "gRPC error message.",
        "data": {
            "code": "CO-01",
            "name": "Test"
        }
    }
}

But, when I call the gripmock server, it responds with:

• Status: 10 (ABORTED)
• Response: gRPC error message.
• Trailers:
  • content-type: application/grpc

The error-code & error-message that I put on output.headers is not being sent.

Is it possible for this gripmock to also send the output.headers that I put on stubs when gRPC status != 0?

Thank you in advance!

[rez1dent3]

Hello. I'll try to take a look soon and write here.

[danieljph]

Hi @rez1dent3, thanks for the update.

I've tried using v3.4.2, and now the Metadata contains my output.headers is available if output.code != 0. I tried this using Postman.

But the new problem occurred. Currently, I work with a gRPC client using Java. In Java, the output.code != 0 will be thrown as StatusRuntimeException. This exception only has a method called getTrailers and there is no other way to get the Metadata. So the Metadata that is visible on Postman is not available in this Java gRPC client if output.code != 0.

BTW, I'm not familiar with gRPC, but the gRPC that I tried to mock also put the error-code & error-message in this Trailers and not in Metadata. And also last time I checked before this update, when output.code != 0, this gripmock is also put content-type = application/grpc in Trailers but now it only available in Metadata.

So my next question:

1. Is it possible to have an option on the stubs, so the output.headers can be put in Trailers or Metadata if output.code != 0? Or maybe we could have parameter output.trailers?
2. Or maybe, just put the output.headers in Trailers if output.code != 0?

Thank you very much for helping me! And if it's not possible, that's okay for me. I can still use this gripmock for other cases.

[rez1dent3]

I can only disappoint. So far, nothing, I have this in my plans and even the implementation in the branch locally, but I haven't got around to updating and rolling it out.

[daniele-betsson]

hi @rez1dent3, may I suggest to provide the ability to specify both metadata and trailers separately as part of an output stub definition rather than headers? in .net libraries, the google.Rpc.Status model works by having the server return an grpc-status-details-bin trailer and therefore we would need to mock such trailer to handle different error responses from a mock server

[rez1dent3]

Hello. It's in this PR, but I'm polishing it and trying to keep backward compatibility with v1.x versions, and that's not easy. I can't tell you the time frame, because I can only develop in my free time from work, and there's too much work right now.

[daniele-betsson]

understood, thank you!