[Pkg-utopia-maintainers] Bug#824649: ostree: document how to prepare and update a .deb-based system root

[Simon McVittie]

Package: ostree
Version: 2016.5-2
Severity: wishlist
Tags: help

We should document how to prepare a Debian-derived system with specified
contents (for example task-desktop) for deployment via OSTree, analogous
to what <https://github.com/projectatomic/rpm-ostree> does for Red Hat
systems.

<https://ostree.readthedocs.io/en/latest/manual/adapting-existing/>
has some general notes based on experience of deploying RPM systems
with OSTree, which should be broadly applicable to dpkg systems.

In particular, carrying out the /usr merge (usrmerge) is recommended
when deploying via OSTree, /etc may need some special handling,
dpkg metadata needs to be moved/symlinked/bind-mounted under /usr
(because it is only as mutable as /usr) or removed, and special handling
will be needed for /etc/passwd and /etc/group because the OSTree deployment
includes uids/gids by numeric value. Reserving a uid/gid range for
the OSTree-managed system users in each ostree-deployed Debian derivative,
and using libnss-extrausers or similar, might be useful.

I think this aspect of OSTree is perhaps more practically useful right now
for limited-scope Debian derivatives (Endless? SteamOS?) than it is for
general-purpose Debian or Ubuntu.

    S