code: func (api *API) HTTPHandler(ctx context.Context, grpcAddr string) (http.Handler, error) {
  	enc := new(protoutil.JSONPb)
  	mux := runtime.NewServeMux(runtime.WithMarshalerOption(enc.ContentType(), enc))
  
  	opts := []grpc.DialOption{
  		grpc.WithInsecure(),
  		// Replace the default dialer that connects through proxy when HTTP_PROXY is set.
  		grpc.WithContextDialer(func(ctx context.Context, addr string) (net.Conn, error) {
  			return (&net.Dialer{}).DialContext(ctx, "tcp", addr)
  		}),
  	}
  
  	err := pb.RegisterAdminHandlerFromEndpoint(ctx, mux, grpcAddr, opts)
  	if err != nil {
  		return nil, err
  	}
  	return mux, nil
  }
docs: // HTTPHandler returns an HTTP handler for a REST API gateway to the given grpc address.