[google-compute-engine] Permission denied (publickey,gssapi-keyex,gssapi-with-mic)

You need to follow this instructions https://cloud.google.com/compute/docs/instances/connecting-to-instance#generatesshkeypair

If get "Permission denied (publickey)." with the follow command ssh -i ~/.ssh/my-ssh-key [USERNAME]@[IP_ADDRESS] you need to modify the /etc/ssh/sshd_config file and add the line AllowUsers [USERNAME]

Then restart the ssh service with

service ssh restart

if you get the message "Could not load host key: /etc/ssh/ssh_host_ed25519_key" execute: ssh-keygen -A

and finally restart the ssh service again.

service ssh restart