Allow FileDescriptorSets in place of individual .proto files

[tatemz]

Most protocol buffer and gRPC projects that I have seen involve many proto files that typically exist outside of the client codebase. These large sets of proto files can be compiled into a file descriptor set:

protoc -I . --descriptor_set_out=descriptor-set.bin foo.proto

These descriptor sets can then be consumed during the protoc code generation process with --descriptor_set_in:

mkdir codegen_dir
protoc --descriptor_set_in=descriptor-set.bin --java_out=codegen_dir foo.proto

Rather than having to include many *.proto files, it would be cleaner (IMHO) if we could use a descriptor set. Example:

sources:
  - name: MyGrpcApi
    handler:
      grpc:
        endpoint: localhost:50051
        protoFilePath: foo.proto # this will still be needed to identify which proto definition in the descriptor set should be used.
        fileDescriptorSet: descriptor-set.bin
        serviceName: Example # maybe this isn't needed
        packageName: io.xtech.example # maybe this isn't needed

[tatemz]

Adding a possible scenario to this feature request, it could be feasible for a single descriptor set to be passed in and all of the services contained in it automatically added without having to specify the descriptors within it. 🤔

[ardatan]

Sounds cool! Do you think you can create a PR so we can merge it and release a new version with this feature?

[tatemz]

I'll work on it. Been reading up on how to do it and there might be a potential showstopper.

In order to convert a FileDescriptorSet into a Root object (used by graphql-mesh), we'd need to use the descriptor extension.

Then we'd need to set the packageDefinition variable using createPackageDefinition from grpc/grpc-node. Unfortunately, that function is not exported and grpc/grpc-node#550 was closed.

Looks like others have opened up issues on protobuf.js (protobufjs/protobuf.js#1117). I'll keep digging and code up a sample PR if I can.

[tatemz]

Okay, I shifted gears and am starting with reflection support. I did fiddle with using statically generated descriptor sets, but was having some trouble with decoding them.

Check out #1086. Once reflection is working. It shouldn't be too hard to also support file descriptor sets.

[ardatan]

gRPC handler supports FileDescriptorSets;
https://github.com/Urigo/graphql-mesh/blob/master/packages/handlers/grpc/yaml-config.graphql#L18