Announce: fedostree/rpm-ostree v2014.3

[Dennis Jacobfeuerborn]

On 21.01.2014 08:30, Colin Walters wrote:
> Hi Dennis,
>
> On Tue, 2014-01-21 at 07:40 +0100, Dennis Jacobfeuerborn wrote:
>
>> Interesting. I've downloaded the VM Image and tried to understand the
>> setup.
>
> Some bits are documented here
> https://people.gnome.org/~walters/ostree/doc/layout.html
>
>> Apparently there exist sort of two root trees / and /sysroot in
>> the system with some links targeting the /sysroot tree.
>
> With OSTree, you boot directly into a chroot - dracut switches root and
> starts systemd right after mounting the rootfs.  See:
> https://git.gnome.org/browse/ostree/tree/src/switchroot/ostree-prepare-root.c
>
> /sysroot is a bind mount to the real root /.
>
>> What I'm
>> wondering about is that /dev/mapper/fedora-root is mounted several times
>> on /, /var, /usr and /sysroot (twice!) sometimes rw and sometimes ro.
>
> /usr is simply a bind mount to itself so it can be mounted read-only.
> This is important because otherwise one could corrupt the object store
> in /ostree/repo by mutating the hardlink farm in /usr.
>
> Note the /usr here is
> really /ostree/deploy/fedostree/deploy/<checksum.serial>/usr as seen
> from the physical root.
>
> /var is a special bind mount to /ostree/deploy/fedostree/var which is
> shared between each deployment (chroot).
>
>> The impression I get is that /sysroot is the actual root fs in the image
>> and / the ostree directory at least that's what the links seem to
>> suggest. I still don't understand the mount-voodoo though. Is there some
>> documentation about this available?
>
> I'll look at adding more to the gtk-doc, though I suspect I may need to
> make a separate "system administrators new to OSTree" document which is
> a bit distinct from the "how to use OSTree underneath your package
> manager" document that the current one is.
>
>

Thanks for the information. I think I was thrown off by the fact that 
the root device is mounted in several places with different content but 
now I realize that's probably because the "external" path isn't 
available from inside the jail so mount can only display the device. 
Previously I've only used bind mounts in a non-chroot context.

Regards,
   Dennis