Register a server unary interceptor for authorization per RPC calls.

main.go

func init() {
	grpcLog = grpclog.NewLoggerV2(os.Stdout, os.Stderr, os.Stderr)
	grpclog.SetLoggerV2(grpcLog)
}
func main() {
	lis, err := net.Listen("tcp", port)
	if err != nil {
		grpcLog.Fatalf("failed to listen: %v", err)
	}
	// Creates a new gRPC server with UnaryInterceptor
	server := grpc.NewServer(
		withServerUnaryInterceptor(),
	)
	pb.RegisterEventStoreServer(server, &eventStore{})
	server.Serve(lis)
}
func withServerUnaryInterceptor() grpc.ServerOption {
	return grpc.UnaryInterceptor(serverInterceptor)
}