I am a newbee to Google Cloud, however, I setup the project based on Standard App Engine based for my Node.JS application. I downloaded the code from GIT and able to deploy. In my code, it tries to make a Mongo connection to my Replication Server that is hosted at Atlas MongoDB (I guess it's on AWS EC2 instance). I have access control enabled so only server to server with known IPs can connect to my MongoDB.
Obviously I was expecting the connection from my freshly deployed app to fail. So to remediate I want to add the external IP of the instance from Google Cloud (whatever is the Public IP that is seen) to Mongo Network Access. I tried a few IP address I thought are the right ones but it's not working. I see the connection is trying to make to Atlas but it's failing because I am not sure what Public IP address is seen from AppEngine (Docker Instance?)where my app is running.
I tried 0.0.0.0/0 - open to all clients and my app works just fine, however I definitely don't want to open MongoDB access to entire world. If anybody knows more about Google Cloud please help.
Thanks in advance for replying if you have important info to share.