When creating a service I see in the list of internal endpoints an entry the looks like myservice.sandbox-cluster:0 TCP along with the ports I explicitly opened. What is the port 0 entry for?
If you are using the GCE Load Balancer, port 0 may be created. port 0 usually means "use any random free port".
Here is the GitHub issue. Here is more info. Email thread about this is here.