1.proto

syntax = "proto3";
option go_package = ".;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;
}

2.server

from __future__ import print_function
from concurrent import futures
import logging
import grpc
import helloworld_pb2
import helloworld_pb2_grpc
class Greeter(helloworld_pb2_grpc.GreeterServicer):
    def SayHello(self, request, context):
        for key, value in context.invocation_metadata():
            print('Received initial metadata: key=%s value=%s' % (key, value))
            return helloworld_pb2.HelloReply(message='Hello,%s!' % request.name)
        def serve():
            server = grpc.server(futures.ThreadPoolExecutor(max_workers=10))
            helloworld_pb2_grpc.add_GreeterServicer_to_server(Greeter(), server)
            server.add_insecure_port('[::]:50051')
            server.start()
            server.wait_for_termination()
if __name__ == '__main__':
    logging.basicConfig()
    serve()

3.client

from __future__ import print_function
import logging
import grpc
import helloworld_pb2
import helloworld_pb2_grpc
def run():
    # NOTE(gRPC Python Team): .close() is possible on a channel and should be
    # used in circumstances in which the with statement does not fit the needs
    # of the code.
    with grpc.insecure_channel('localhost:50051') as channel:
        stub = helloworld_pb2_grpc.GreeterStub(channel)
        response, call = stub.SayHello.with_call(
            helloworld_pb2.HelloRequest(name='you'),
            metadata=(
                ('name', 'golang'),
                ('password', 'jetbrains')
            )
        )
        print("Greeter client received: " + response.message)
if __name__ == '__main__':
    run()