[Ruby] How do I raise a Rich Error from Ruby Server?

[jua...@flexport.com]

According to gRPC Error Handing, Richer error model contains much more information than the standard one comes with gRPC default. So I decided to use it for my gRPC servers for Errors.

In Java, I am able to easily use it and return Error in response as 

Status status = Status.newBuilder()

        .setCode(Code.INVALID_ARGUMENT.getNumber())

        .setMessage("Required argument is empty.")

        .addDetails(Any.pack(DebugInfo.newBuilder().addStackEntries("This is a sample stack trace").build()))

        .build();

      responseObserver.onError(StatusProto.toStatusRuntimeException(status));

However, I also have gRPC servers which are written in Ruby. And I can't find a way to raise an exception or return error status as in Java.

I did this:

    debug_info = Google::Rpc::DebugInfo.new(

      stack_entries: ["1", "2"] ,

    )

    error_status = Google::Rpc::Status.new(

      code: 3,

      message: "msg",

      details: [Google::Protobuf::Any.pack(debug_info)]

    )
# no way for me to throw exception from error_status

After i initialized a Google::Rpc::Status instance, it seems like there is no way for me to raise an exception from error_status I created. Anyone has any idea how I can do it in Ruby? Thanks!

[Juanyi Feng]

Answering my own question - 

I am about to build workaround by doing this:

debug_info_any = Google::Protobuf::Any.pack(
 Google::Rpc::DebugInfo.new(
 stack_entries: ["stack_entries 1", "stack_entries 2"],
 )
)
rich_error = Google::Rpc::Status.new(
 code: 1,
 message: 'matching message',
 details: [debug_info_any],
 )
encoded_rich_error = Google::Rpc::Status.encode(rich_error)
raise GRPC::BadStatus.new(
 GRPC::Core::StatusCodes::INVALID_ARGUMENT,
 "invalid argument msg",
 'grpc-status-details-bin' => encoded_rich_error)

But I still wonder if there's a better approach in Ruby. Thanks!

[Alexander Polcyn]

Suggest taking a look at this test for usage of the google.rpc.Status protobuf-based richer error model: https://github.com/grpc/grpc/blob/5a419c65b02b069f4c92623678743a3ddddc53cb/src/ruby/spec/google_rpc_status_utils_spec.rb#L182

However, existing support for the richer error model in ruby is focused on client side error extraction. That is, there is a utility

for extracting rich errors on the ruby client side, but there's not a corresponding utility at the server side for sending one.

I.e., your code sample above is currently the best way of sending a rich error from a ruby server. This TODO in the

test summarizes the current state of things: https://github.com/grpc/grpc/blob/5a419c65b02b069f4c92623678743a3ddddc53cb/src/ruby/spec/google_rpc_status_utils_spec.rb#L128