Simon McVittie <s...@debian.org> writes: > Persisting a container root filesystem between multiple operations comes > with some serious correctness issues if there are "hooks" that can modify > it destructively on each operation: see <https://bugs.debian.org/499014> > and <https://bugs.debian.org/994836>. As a result of that, I think the > only model that should be used in new systems is to have some concept of > a session (like schroot type=file, but unlike schroot type=directory) > so that those "hooks" only run once, on session creation, preventing > them from arbitrarily reverting/overwriting changes that are subsequently > made by packages installed into the chroot/container (for example dbus' > creation of the messagebus uid/gid in #499014, and exim4's creation of > Debian-exim in #994836).
I'm not entirely sure that I'm following the nuances of this discussion, so this may be irrelevant, but I think type=btrfs-snapshot provides the ideal properties for container file systems. This unfortunately require file system support and therefore cannot be used unless you've already embraced a file system with subvolumes, but if you have, you get all of the speed of a persistent container root file system with none of the correctness issues, because you get a fresh (and almost instant) clone of a canonical root file system that is discarded after each build. I use that in combination with a cron job to update the source subvolume daily to ensure that it's fully patched. Unfortunately, there's no way that we can rely on this, but it would be nice to continue to support it for those who are using a supported underlying file system already. -- Russ Allbery (r...@debian.org) <https://www.eyrie.org/~eagle/>
