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I have a single protobuf which generates out C# and Go code.

The protobuf contains:

syntax = "proto3";
package myprotobuf;
option go_package = "gitlab.example.com/mycompany/myprotobuf.git";

I'm using go-micro and protoc-gen-micro for my Go GRPC. I'm using Go modules for my Go packages. I'm pushing generated Go code to my protobuf repository for a few reasons: (a) Git submodules can be painful to work with (b) a protobuf referencing a type in an external package requires that external package to have a defined absolute package URL and (c) that's how Google do it (ref e.g. structpb) so it seems like that's the "standard".

The C# server / client generated from that proto serve / hit an endpoint at "/myprotobuf.Service/Method", and work fine.

GRPC_TRACE for C# gives:

Decode: ':path: /myprotobuf.Service/Method', elem_interned=1 [1], k_interned=1, v_interned=1 (edited)

The Go / go-micro client calling the C# server gives:

Decode: ':path: /myprotobuf.git.Service/Method', elem_interned=0 [2], k_interned=1, v_interned=0

followed by an error. Note that the path is different. Breakpoints and Console.WriteLine's in the C# GRPC handler never get hit, which makes sense since we're not hitting a known endpoint.

What's the solution for this?

  • go get seems to require the .git at the end of the package URL.
  • go modules require the "module" and "package" definitions to match the URL.
  • C# won't like a "." in the namespace.

So it seems like Go and C# are both always going to prefix the endpoint with what the think the package / namespace is, and they're never going to agree on what the package / namespace should be.

Is there a way to override the namespace prefixed to the GRPC endpoint?

George
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1 Answers1

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One workaround I've found is to sit the package a level under the protos in a "mypb" directory:

package mypb;
option go_package = "gitlab.example.com/mycompany/myprotobuf.git/mypb";
option csharp_namespace = "MyCompany.Protobuf.MyPB";

It's a bit of a hack, but I don't mind it too much, especially since it sits the generated code out of the way of the proto source that I actually care about. This way the generated C# and Go agree on the namespace / package that they prefix endpoints with. Thankfully the camel case MyPB vs lower case mypb doesn't seem to matter.

George
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