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- Ensure that your Docker or Containerd containerd environment meets the minimum deployment requirements.
- Open all required ports on the hosts, as list in Port Usage for Bare-Metal Hosts, in addition to the ports required for firewalls.
- Ensure that there are no other processes using port 53 on the host system on which your host will be deployed. For example, some Ubuntu systems running local DNS cache (system-resolved) might occupy port 53, and your host might not function properly in this case.
- Dind (Docker-in-Docker) configuration is not supported for host deployments.
- Avoid CIDR overlapping with the default CIDR.
- No K3s binary should be placed in this directory:
/usr/local/bin/. - SELinux policy is properly set up.
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Disable unattended upgrades on Ubuntu. The unattended upgrades feature is enabled by default, and it runs at system boot without user's permission. Unattended upgrades could cause all containers to be terminated and new containers to be created. When this happens, the host will stay in a bad state and cannot be recovered. To disable unattended upgrades on Ubuntu and its derivatives, run the following command:
$ sudo dpkg-reconfigure unattended-upgrades
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