[systemd-devel] CoreOS Goal Question: Should we be aiming to be able to boot with an empty /etc?

[Colin Walters]

On Mon, 2013-01-07 at 15:26 +0100, Lennart Poettering wrote:

> BTW, Kay and I were thinking about coming up with a simple scheme that
> could pre-initialize a couple of files in /etc and /var that cannot
> really sensibly be dropped. For example, UID assignemnts unfortunately
> cannot be shipped in packages from the distro, they must happen
> dynamically on the local system, 

I ship them statically:

http://git.gnome.org/browse/gnome-ostree-integration/tree/src/lib-passwd

But I don't have "packages" - there is no ability to dynamically mutate
your root filesystem while it's running.

(Note also that gnome-ostree has both /etc/passwd and /lib/passwd, via
 https://github.com/aperezdc/nss-altfiles )

> (wouldn't it be awesome to have 128bit IDs like a certain other
> OS?).

Yep, but not a small change...

>  What we were thinking of is that RPMs could ship minimal
> "manifest" files that include information about which users need to be
> recreated if /etc is dropped and which file owenerships they must
> match. After flushing /var and /etc, playing back these manifests should
> execute the minimal operations to get pack /etc with passwd/group
> initialized and match the UIDs used on the fs and maybe a few other
> things.

Well note in the gnome-ostree split-password model, dropping /etc only
deletes users for /home, not the OS.

But dynamically allocating system users per-boot and ensuring that
/etc and /var matches would still be interesting.