journalctl -u
journalctl -u <service> [-n N] [--no-pager] [-f]
Risk: Safe
What it does
Reads a service's diary: the log lines systemd keeps for it.
When to use it
The kubelet stopped or keeps failing, and you want to know why.
Example
$ journalctl -u kubelet -n 20 --no-pagerThe kubelet's last 20 diary lines, printed all at once.
$ journalctl -u kubelet -fKeep watching for new lines. Ctrl+C stops.
Learn it in: The kubelet: systemctl and journalctl · Official docs