gRPC error codes in go-kit

[Alejandro Delgado Garcia]

Hi,

Is it possible to integrate somehow with go-kit standard gRPC codes https://github.com/googleapis/googleapis/blob/master/google/rpc/code.proto?

I was following the examples like the addsvc and at the same time applying that example into my micro service but I haven't found a way to properly return those codes to the client and I'm always getting the UNKNOWN error. I'm wondering what's the best practice to integrate the use of https://godoc.org/google.golang.org/grpc/status in go-kit, how can I link these codes with my bussines logic, which layer should take care of return the official gRPC codes and if you guys recommend the use of the status package. Any insights will really appreciate it.

Other than that go-kit is an amazing toolkit that has been perfect and useful to quickly start a micro service. Thanks.

[Bas Van Beek]

Hi there,

Good question. Yes it is possible but unfortunately we haven't really provided a good example in the Go kit repository for it. There is one item that needs addressing to make it easier which is the Go kit gRPC transport client. It will treat any gRPC code other than OK as a hard transport error. The trick is to catch the gRPC return details in an endpoint middleware and separate out business from transport / hard errors. Otherwise you'll end up tripping things like circuit breakers and retry logic. 

An example of using gRPC status codes with Go kit can be found in my example repo: https://github.com/basvanbeek/opencensus-gokit-example

On the server end, encoding the proto message and the gRPC status is done in the encode response handler as seen here: https://github.com/basvanbeek/opencensus-gokit-example/blob/master/services/device/transport/grpc/service.go#L66

On the client end, catching the gRPC response and shoehorning it into the correct endpoint payload for further endpoint middlewares and decoding steps, see: https://github.com/basvanbeek/opencensus-gokit-example/blob/master/clients/device/grpc/encode_decode.go#L33

hope this helps,

Bas

[Alejandro Delgado Garcia]

Thanks a lot Bas. I'm going to take a look to your example asap.

Alejandro.