You can use below articles to get the desired result: Run kubernetes inside LXC container or Run Kubernetes as Proxmox container

To summarize above articles you should perform next steps:

1) Add overlay driver for docker.

echo overlay >> /etc/modules

2) Add more privileges to container by modifying container config

lxc.apparmor.profile: unconfined
lxc.cap.drop: 
lxc.cgroup.devices.allow: a
lxc.mount.auto: proc:rw sys:rw

3) Use shared filesystem to /etc/rc.local

echo '#!/bin/sh -e
mount --make-rshared /' > /etc/rc.local

4) Init cluster using kubeadm