Docker moved out of lxc long time ago

Docker by default uses their own libcontainer now but you can change that. In fact last time I checked it supported quite a few via execution drivers like OpenVZ, systemd-nspawn, libvirt-lxc, libvirt-sandbox, qemu/kvm, BSD Jails, Solaris Zones, chroot

actually it only does two, lxc and libcontainer (aka native) https://github.com/docker/docker/blob/master/daemon/execdriv...

used to. Now-a-days it uses libcontainer.