Created attachment 151361 [details]
auto-chroot merged back from base, mtree follows separately

There was a lot of rumor about auto-chrooting for bind because out-of-the-box chroot support was removed along with bind from base starting with FreeBSD-10, see https://lists.freebsd.org/pipermail/freebsd-stable/2013-December/076028.html

I share the opinion of the majority – it's a significant regression.
So I hacked a quick back-merge from what I appreciated having had in base.
It's meant to change as less as possible, and has been barely tested, but does work well in my environment.
It's most probably no long term solution, but a quick one for those looking for the old behaviour we were used up to FreeBSD-10.
All you have to add is
named_chrootdir="/var/named"
to your /etc/rc.conf and make sure the directory you define does exist.

I simply took the old rc.d-script and back-merged the routines with little matching.
Inside chroot, %%PREFIX%% will be stripped, so your config is in /var/named/etc/namedb e.g. (not in /var/named/usr/local/etc/namedb!!!)

Feel free to like/dislike/adapt/use/forget it ;-)

For easier reading, I made two patches, especially because I'm unsure if it's a good idea to install BIND.chroot.dist into %%PREFIX%%/etc/mtree. There are countless other ways to do it, but like I mentioned, I wanted to make this addition minimal-invasive in port's perspective.