[kubelet] [summary_sys_containers.go:47] Failed to get system container stats for "/system.slice/docker.service": failed to get cgroup stats for "/system.slice/docker.service": failed to get container info for "/system.slice/docker.service": unknown container "/system.slice/docker.service"
This error may appear in the kubelet logs after a reboot if kubelet starts after docker. In our experience this error is harmless. It’s possible to stop the error from appearing in the logs by restarting kubelet with systemctl restart kubelet.