On Mon, Jan 10, 2022 at 02:53:52PM -0700, Chris Murphy wrote:
Should /usr be independently portable? And is that with a version
matched /opt, or can there be mix and match revisions of /usr and
/opt?
We have three similar locations: /usr (system vendor tree),
/usr/local (admin non-packages installations), /opt (external vendor tree).
In other words, both /usr and /opt are for packages, but from different
sources. As an admin, you'd want to treat both package types the same,
and e.g. roll them back together. So having a separate tree for /opt
doesn't make much sense.
[At some point in the future] /opt should be renamed to /usr/opt and
symlinked for backwards compat.
If /usr is to be truly portable and have e.g. 'rpm query, verify,
remove, reinstall' work as expected, you need the metadata (the
database) representing its state to always come along for the ride.
Either the database is already in /usr, or you have to make sure /usr
and /state are inseparable.
If /usr and /state are inseparable, and if rpm can also describe
anything in /etc or /var or /opt, then all or part of those
directories are also inseparable from /state. And thus /usr. So I
think /state doesn't help.
Yeah, /state doesn't help with anything. It'd be just some part of the
whole system state, without a clear separation of why this particular
subset. My preference: /usr/lib/sysimage/rpm > /var/lib/rpm > /state.
To what degree do rpm and dnf intend to touch locations outside of
/usr *and care* about tracking those changes?
Traditionally, packages installed all kinds of files all over the place.
But we're slowly and painfully moving towards the model where:
1. packages are only allowed to install under /usr, /var, and /etc.
(Or under /opt, but I'd want to move that to /usr/opt…)
2. packages must support /var/cache being wiped at any time, and
most packages support anything under /var being wiped at any time.
3. systemd and other projects are trying to only use /etc for local
admin state, and support "factory reset" by wiping /etc and /var.
