grpc-client.go

func callSayHello(ctx context.Context, c api.HelloServiceClient) {
	md := metadata.Pairs(
		"timestamp", time.Now().Format(time.StampNano),
	)

	ctx = metadata.NewOutgoingContext(ctx, md)
	response, err := c.SayHello(ctx, &api.HelloRequest{Greeting: "World"})
	if err != nil {
		log.Fatalf("Error when calling SayHello: %s", err)
	}
	log.Printf("Response from server: %s", response.Reply)
}