gRPC with Sonora

In libsodium v2.50 the gRPC API was added. This works by connecting the WSGI application with a gRPC server using the sonora package. This allows for having a gRPC application running underneath a http service on the same socket.

Generating code for protobufs

If you go to src/gRPC you will see a folder named “protobufs”. This folder contains all the protobufs in the project. Lets create one inside the folder.

file: hello.proto

// The greeting service definition.
service Greeter {
  // Sends a greeting
  rpc SayHello (HelloRequest) returns (HelloReply) {}
}

// The request message containing the user's name.
message HelloRequest {
  string name = 1;
}

// The response message containing the greetings
message HelloReply {
   string message = 1;
}

Now to create the files for the protobuf instead of using the grpc toolchain directly we can use the libsodium wrapper.

python3 -m libsodium create gRPC hello.proto

If you look in the src/gRPC directory now you will see that there is a new folder named after our protofile(hello). This folder will contain the classic gRPC files but with one extra file named hello.py. This file will be our service.

import src.gRPC.hello.hello_pb2_grpc as hello_pb2_grpc

def serve(server):
    hello_pb2_grpc.add_ExampleServicer_to_server(
        AppServicerHere(), server
    )

As you can see we get a template for implementing a servicer from our proto file. Here is the fully completed version of the file.

import src.gRPC.hello.hello_pb2_grpc as hello_pb2_grpc
from src.gRPC.hello.hello_pb2 import (
    HelloReply
)

class GreeterService(hello_pb2_grpc.GreeterServicer):

    def SayHello(self, request, context):
        return HelloReply(message=f"Hi, {request.name}")


def serve(server):
    hello_pb2_grpc.add_GreeterServicer_to_server(
        GreeterService(), server
    )

Note

The sonora library only supports HTTP 1.1 as of libsodium version 2.50.

Regeneration

If you edit a proto file and wish for the gRPC files to be regenerated use the following command:

python3 -m libsodium create gRPC example.proto --regen