Re: [Libguestfs] Weird results from g.sh()
I ended up with the following logic (which is pretty close to what you
suggested, had to unmount sysfs first to create directories there)
def update(self, g):
if self.boot_type == BootType.UEFI:
# On rhel7 and sles12/15 the grub config is set to non efi commands
# due to a weak uefi detection algorithm which doesn't work from a
# chrooted environment (checks for [ -d /sys/firmware/efi ]).
# libguestfs bind-mounts the sysfs of the appliance to /sys when
# invoking g.sh()/command() - Therefore, /sys/firmware/efi does
# not exist. Hack around this behavior by unmount /sys and
# creating /sys/firmware/efi dir before running grub2's mkconfig.
g.sh(f'umount /sys && mkdir -p /sys/firmware/efi && '
f'{self.mkconfig} -o {self.config}')
else:
g.command([self.mkconfig, '-o', self.config])
return True
I'm pretty sure that should be fixed in virt-v2v too (although I'm a
bit lazy do write that OCaml equivalent of this and test it).
So just a heads up on the mailing list.
Sam
On Thu, Aug 27, 2020 at 12:28 PM Sam Eiderman <sameid(a)google.com> wrote:
I see, thanks for the clarification.
On Thu, Aug 27, 2020 at 12:05 PM Richard W.M. Jones <rjones(a)redhat.com> wrote:
>
> On Thu, Aug 27, 2020 at 11:24:57AM +0300, Sam Eiderman wrote:
> > Yes, I understand that, I am just surprised to know that we bind /sys
> > for g.sh() commands.
> >
> > However, "g.command([self.mkconfig, '-o', self.config])"
shouldn't
> > have the appliances /sys available (I looked briefly in command.c and
> > I don't see the same bind-mount code), or maybe I'm missing something.
>
> guestfs_sh, guestfs_sh_lines, guestfs_command, guestfs_command_lines
> all attempt to bind-mount /sys and other directories into the chroot
> while running the command. (See daemon/sh.c)
>
> Anyway I misunderstood before - I thought you were trying to run grub
> to install the bootloader. Running grub2-mkconfig as done in virt-v2v
> should be fine since AIUI it's just concatenating some configuration
> files together.
>
> > I thought I could use my g.mkdir_p('/sys/firmware/efi') hack, but
> > since it didn't work, I'm now resort to explicitly handling this
> > failure after running the mkconfig command:
>
> The mkdir didn't work since that directory will be covered by the bind
> mount when the command is running.
>
> I'm not sure there's a good answer here, maybe something like:
>
> g.sh ("
> mkdir -p /sys/firmware/efi
> # create some files in /sys/firmware/efi to trick grub
> grub2-mkconfig -o ...
> ")
>
> although this may modify the appliance's real /sys.
>
> Rich.
>
> --
> Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
> Read my programming and virtualization blog: http://rwmj.wordpress.com
> libguestfs lets you edit virtual machines. Supports shell scripting,
> bindings from many languages. http://libguestfs.org
>