Yes, this feels like something out of Dgraph’s scope. Hard to tell what it is. @joaquin what do you think? there is some extra config to permit 8080 port to be exposed on GCE? Maybe is similar to AWS.
Now for the firewall rules, GCE only allows by default port 22, unless check boxed HTTP/HTTPS, then explicitly only the ports 80 and 443 are open as well. For all other ports you have to add a new firewall rule to the VPC. Google uses a tags to apply the firewall rules set for your VPC for a particular GCE instance.
Thus, if you created a firewall rule (ingress of 8080) that applies to tag of dgraph-http for example, you would then take the network interface of that GCE instance for public IP and add the tag dgraph-http. After google will retroactively apply that rule to the GCE.