title: Routing requests to GAE Flex from Cloud VPN?
body: <p>I know from <a href="https://stackoverflow.com/questions/37137914/is-it-possible-to-use-google-app-engine-with-google-cloud-vpn">this question</a> that you can launch flex instances in a specified VPC/subnetwork and consequently make it available in a Cloud VPN, but I'm not sure what to do from there to route requests?</p>
  
  <p>Is the flex instance still reachable via the *.appspot.com URL? is it accessed via internal IP? How do I make sure requests from an on-premise application is routed to my flex instance?</p>