How to mount a local directory or volume with lxd

1. expand the range of uid and gid available by editing /etc/subuid and /etc/subgid

brandon@somehost:~$ sudo cat /etc/subuid

brandon@somehost:~$ sudo cat /etc/subgid

2. restart lxd to apply those changes
brandon@somehost:~$ sudo /etc/init.d/lxd restart
[ ok ] Restarting lxd (via systemctl): lxd.service.

3. launch your container
brandon@somehost:~$ lxc create :ubuntu $your_container
where you replace the $your_container value with whatever you would like to call your lxd container

4. enable an isolated idmap for your container
brandon@somehost:~$ lxc config set $your_container security.idmap.isolated true

5. map the local user ids and group ids to the in container uid and gid
brandon@somehost:~$ lxc config set bootybox raw.idmap "both 1000-2000 3000-4000"
where the parameters being passed in this example mean both (uid, and gid) in the range of 1000-2000 on the local host will be mapped to the range of 3000-4000 inside of the lxd container.

ex: uid 1001 on the local host = uid 3001 inside of the container

6. add your media
brandon@somehost:~$ lxc config device add $your_container media disk source=/zpool1/media/ path=/media
media = the name you would like to give this attachment
source = the source on the local host of the directory you would like to share
path = the path inside the container you would like to mount the source (make sure this exists)

7. restart your container for the new mappings to kick in
brandon@somehost:~$ lxc restart bootybox

8. exec into your container and check that all is well
brandon@somehost:~$ lxc exec bootybox bash
root@mycontainer:~# ls -l /media/
total 76
drwxrwx--- 2 3000 3001 2 Jun 2 21:22 games

9. profit.