This page says that port 22 is open for public clusters in GKE:
"For public clusters only. Permits the control plane to access the Kubelet and metrics-server on cluster nodes."
https://cloud.google.com/kubernetes-engine/docs/concepts/firewall-rules
I was wondering is this only used for troubleshooting and metrics or if I remove that firewall rule the cluster will stop working?
Thank you!
Welcome to stackoverflow..,
SSH firewall rule not required for the correct functioning of the cluster. If that firewall rule is removed then the kubectl logs, attach, exec, and port-forward commands stop responding.
For more information refer the link
In this stackoverflow link you can clearly find what type of errors will occur if that firewall rule has been removed.
But don't delete as suggested by John Hanley.
Warning: Do not modify or delete firewall rules created by GKE, or you might encounter unexpected behavior in your clusters.– John Hanley