As you may already know, GCP Projects represent a trust boundary within an organization. Hence, inter-project communication between App Engine services would require Public IP communication or using Shared VPC[1]. So, depending on your setup, there really should be no internal communication between App Engine Services or Other GCP services over different projects.
Additionally, about using Public App Engine IP addresses, as illustrated in this document [2] App Engine hosts services on a dynamic public IP address of a Google load balancer. Due to that, the IP address can be changed any time and any Static IP can not be provided. For outbound services, a large pool of IP addresses are used which you can obtain as outlined in this document[3]. With all that being said, can you shed more light about the metrics being collected? The metrics are for an App Engine application in Project B or where? What product's metrics exactly are you looking to pull? [1]https://cloud.google.com/vpc/docs/shared-vpc [2]https://cloud.google.com/appengine/kb/#private-ip [3]https://cloud.google.com/appengine/kb/#static-ip [4]https://cloud.google.com/logging [5]https://cloud.google.com/monitoring -- You received this message because you are subscribed to the Google Groups "Google App Engine" group. To unsubscribe from this group and stop receiving emails from it, send an email to google-appengine+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/google-appengine/b89d98b3-f8cb-4b7f-af7a-7e6262fd26bfo%40googlegroups.com.
