Docker Volumes on host with SELinux

(A reminder for next time I end up scratching my head on this)

When mounting a Volume on a host with SELinux enabled use the add a trailing :Z to the volume syntax, e.g.:

docker run -v /var/db:/var/db:Z rhel7 /bin/sh

This will label the mounted directory to allow access from the container - read more here:

http://www.projectatomic.io/blog/2015/06/using-volumes-with-docker-can-cause-problems-with-selinux