Setup Google Compute Engine to only be accessible from a Google App Engine application?

Question

Google Compute Engine instances can be secured behind a firewall that allows you to open the instance by ports and/or IP addresses.

Google App Engine doesn't use a single IP address.

I have a Compute Engine server running Nginx that I would like to completely lock down so the only way to access it is through an application on Google App Engine, is this possible?

If not, is there a simple way to send a POST request with a string of characters to Nginx, that if not present, the Nginx server would send people to a 404?

Answer 1

Use HTTP authentication as per the question Dan has linked to. There is no viable network/IP/firewall mechanism to restrict access.

The HTTP authentication works just fine!