Upgrading Node Operating Systems

• Consider adding an extra node temporarily if your cluster lacks spare capacity.
• Sequentially drain, update, and reboot each node, then return it to service.
• To streamline this process, install the Kubernetes Reboot Daemon (Kured). Ensure the nodes' OS supports unattended upgrades, especially for security patches. For Ubuntu nodes, include the following in your configuration file before creation:

additional_packages:
- unattended-upgrades
- update-notifier-common
post_create_commands:
- sudo systemctl enable unattended-upgrades
- sudo systemctl start unattended-upgrades

Review the Kured documentation for details on setting maintenance windows and other configurations.