Getting Unimplemented desc = unknown service error gRPC

Question

In one of my services that happens to be my loadbalancer, I am getting the following error when calling the server method in one of my deployed services:

rpc error: code = Unimplemented desc = unknown service fooService.FooService

I have a few other services set up with gRPC and they work fine. It just seems to be this one and I am wondering if that is because it is the loadbalancer?

func GetResult(w http.ResponseWriter, r *http.Request) {

    conn, errOne := grpc.Dial("redis-gateway:10006", grpc.WithInsecure())       
    defer conn.Close()

    rClient := rs.NewRedisGatewayClient(conn)
    result , errTwo := rClient.GetData(context.Background(), &rs.KeyRequest{Key: "trump", Value: "trumpVal"}, grpc.WithInsecure())

    fmt.Fprintf(w, "print result: %s \n", result)   //prints nil
    fmt.Fprintf(w, "print error one: %v \n", errOne) // prints nil
    fmt.Fprintf(w, "print error two: %s \n", errTwo) // prints error

}

The error says there is no service called fooService.FooService which is true because the dns name for the service I am calling is called foo-service. However it is the exact same setup for my other services that use gRPC and work fine. Also my proto files are correctly configured so that is not an issue.

server I am calling:

 func main() {

    lis, err := net.Listen("tcp", ":10006")
    if err != nil {
        log.Fatalf("failed to listen: %v", err)
    }

    grpcServer := grpc.NewServer()
    newServer := &RedisGatewayServer{}
    rs.RegisterRedisGatewayServer(grpcServer, newServer)

    if err := grpcServer.Serve(lis); err != nil {
        log.Fatalf("failed to serve: %v", err)
    }

}

The function I am trying to access from client:

func (s *RedisGatewayServer) GetData(ctx context.Context, in *rs.KeyRequest)(*rs.KeyRequest, error) {

     return in, nil
}

My docker and yaml files are all correct also with the right naming and ports.

Answer 1

thanks @dolan's for the comment, it solved the problem.

Basically we have to make sure, the method value should be same in both server and client (you can even copy the method name from the pb.go file generated from server side)

func (cc *ClientConn) Invoke(ctx context.Context, method string, args, reply interface{}, opts ...CallOption) error {

this invoke function will be there inside all the methods which you have implemented in gRPC service.

Answer 2

I had this exact problem, and it was because of a very simple mistake: I had put the call to the service registration after the server start. The code looked like this:

err = s.Serve(listener)
if err != nil {
    log.Fatalf("[x] serve: %v", err)
}

primepb.RegisterPrimeServiceServer(s, &server{})

Obviously, the registration should have been called before the server was ran:

primepb.RegisterPrimeServiceServer(s, &server{})

err = s.Serve(listener)
if err != nil {
    log.Fatalf("[x] serve: %v", err)
}