I want to proxy all RPC methods of an existing, established gRPC client connection on a gRPC Go server.

In theory, what I wanted would be something like

import (
    "fmt"
    "net"

    pb "google.golang.org/grpc/examples/helloworld/helloworld"

    "google.golang.org/grpc"
)

func server(port int, client pb.GreeterClient) {
    lis, err := net.Listen("tcp", fmt.Sprintf(":%d", port))
    if err != nil {
        panic(err)
    }

    s := grpc.NewServer()
    // this fails:
    // cannot use client (variable of type helloworld.GreeterClient) as helloworld.GreeterServer
    // have SayHello(context.Context, *helloworld.HelloRequest, ...grpc.CallOption) (*helloworld.HelloReply, error)
    // want SayHello(context.Context, *helloworld.HelloRequest) (*helloworld.HelloReply, error)
    pb.RegisterGreeterServer(s, client)
    
    // other registrations specific to this server

    if err := s.Serve(lis); err != nil {
        panic(err)
    }
}

I could create a wrapper, encapsulating the client and mapping each request to the corresponding client method. But as there are many methods, and they might also vary over time, I’d prefer a solution without additional boilerplate, if possible.

Do you see any straightforward alternative to use the client as server implementation?