On Monday, November 29, 2021 4:46:42 PM CET Daniel P. Berrangé wrote:
On Mon, Nov 29, 2021 at 04:38:26PM +0100, Pavel Raiskup wrote:
> On Monday, November 29, 2021 4:02:23 PM CET Daniel P. Berrangé wrote:
> > On Mon, Nov 29, 2021 at 03:24:12PM +0100, Pavel Raiskup wrote:
> > > Hello,
> > >
> > > anyone had a successful experience with Fedora 35 Cloud images, and
> > > guestfish/virt-sysprep?
> > >
> > > Seems like we switched from ext4 or xfs to 'btrfs', and guestfish
> > > doesn't work with the images, am I right? At least I had problems
> > > on EL8 hypervisors so far. >
> > As a general rule, libguestfs is only guaranteed to work if the
> > host OS is the same or newer than the guest OS. It might (and often
> > does) work if the host OS is older than the guest, but that's pot
> > luck.
> > The libguestfs appliance use the host kernel to access the filesystems,
> > so if the guest OS kernel was newer, its filesystem may have used features
> > that the host OS kernel doesn't understand.
> > IOW, my assumption is that Fedora 35 xfs is using fetures that RHEL8
> > xfs doesn't support.
> Ah, not xfs, but you helped me. Now I understand what the message means :-)
> $ virt-sysprep -a ...
> [ 0.0] Examining the guest ...
> virt-sysprep: error: libguestfs error: inspect_os: mount exited with status
> 32: mount: /tmp/btrfse5L6v2: unknown filesystem type 'btrfs'.
> This is the absence of 'btrfs' on EL8. So there's no way out from this
> on any currently supported RHEL, I bet.
I've not tried, but the container Neal points to in the other reply
may still work, if it includes a Fedora kernel vmlinux that libguestfs
can leverage. The host OS kernel is merely libguestfs' default choice,
you can point it to other kernels if you have some available
I can confirm it works, libguestfs-appliance brings kernel-core into the
Though, can I somehow manually point the host's libguestfs to the
alternative kernel (e.g. from extracted kernel-core.rpm from F35)? I
mean.., it is really painful to fix our scripting to use the containerized
libguestfs. If so, any command touching host filesystem needs to be
changed (e.g. copy-in/copy-out). Also command-line arguments (-a) need to
But it is indeed good enough for manual, one-time image tweaks (there are
some minor issues, like absence of Fedora 35 Dockerfile, the image isn't
in registries, etc.).