21bb3bac56
BIND stores dynamically created zones in /var/named by default, which means that this directory needs to be persistent across container restarts. However, we can't just bind mount /var/named into the container because /var/named is empty on the host, but in the container the BIND package populates some necessary initial files in it. To address this, we can point BIND at /var/named-persistent and copy all of the initial config from /var/named at container start, just like we do for other configs. Change-Id: Ic17fb812468f2eb66d9c348b51dfa73a1f216a70