In the K8s documentation the following source range is hardcoded: 130.211.0.0/22. Is this a fixed one or can I get it using some command (e.g. gcloud, kubectl)?
I have tried to inspect the K8s objects but I don't find a this source range in order to create the firewall rule pointed out in the documentation.
That source IP range (130.211.0.0/22) is a fixed, global value that the GCE L7 load balancer will use when issuing health checks. You can read more about it here.