As an operating system we used the same for all docker nodes (Host machine & LXC containers):
* Debian 9.3 (Stretch) with Linux Kernel 4.9.0-5-amd64
In more detail, the manager node is running on the host machine itself, while the provisioning of LXC containers permits the creation of multiple worker nodes on which the galera cluster runs, running on the same host without the need for separate worker machines.