...The kubelet might break on docker's non-standard version numbering (it no longer uses semantic versioning). To ensure auto-updates don't break your cluster look into e.g. yum version lock plugin or apt pin). The target servers must have access to the Internet in order to pull docker images. Otherwise, additional configuration is required. The target servers are configured to allow IPv4 forwarding. If using IPv6 for pods and services, the target servers are configured to allow IPv6 forwarding.
PuSSH is Pythonic, Ubiquitous SSH, a Python wrapper/script that runs commands in parallel on clusters/ranges of linux/unix machines via SSH, ideally where SSH is configured to use Kerberos, RSA/DSA keys, or ssh-agent as to avoid password authentication.