Re: [PATCH] test: fix 'make assets' failure as root

["Richard W.M. Jones" <rjones@redhat.com>]

On Thu, Sep 25, 2025 at 11:40:25AM +0200, Stefano Brivio wrote:
> On Thu, 25 Sep 2025 09:53:06 +0100
> "Richard W.M. Jones" <rjones@redhat.com> wrote:
> 
> > On Thu, Sep 25, 2025 at 01:43:06PM +0800, Yumei Huang wrote:
> > > Running `make assets` under `test` as root fails with a "Permission denied"
> > > error when `prepare-distro-img.sh` invokes `virt-edit` and `guestfish`. This
> > > is due to a known bug in libvirt.
> > > 
> > > Work around the issue by switching to the direct backend.
> > > 
> > > Signed-off-by: Yumei Huang <yuhuang@redhat.com>
> > > ---
> > >  test/prepare-distro-img.sh | 2 ++
> > >  1 file changed, 2 insertions(+)
> > > 
> > > diff --git a/test/prepare-distro-img.sh b/test/prepare-distro-img.sh
> > > index 0d967c9..423eea7 100755
> > > --- a/test/prepare-distro-img.sh
> > > +++ b/test/prepare-distro-img.sh
> > > @@ -3,6 +3,8 @@
> > >  IMG="$1"
> > >  PASST_FILES="$(echo ../*.c ../*.h ../*.sh ../*.1 ../Makefile ../README.md)"
> > >  
> > > +export LIBGUESTFS_BACKEND=direct  
> > 
> > Please add a comment that this is only added as a temporary hack until
> > we can get a proper fix (in libguestfs possibly, see Dan's earlier
> > email).
> 
> On the other hand, regardless of that fix, I would be happy to be run
> this on single-user Alpine L1 guests, eventually, where libguestfs
> doesn't depend on libvirt (see my caveat 2.), and I usually reserve
> very little disk space for those.

The upstream default is backend 'direct'.  In Fedora & RHEL we
override this with 'libvirt':

https://src.fedoraproject.org/rpms/libguestfs/blob/rawhide/f/libguestfs.spec#_714

I don't know what Alpine does, but likely it leaves it at the default.
(You can try: `guestfish get-backend`)

> If you don't have compelling reasons (like you're dropping
> LIBGUESTFS_BACKEND=direct in two weeks), I would simply keep this as
> long as it works. The day you drop that, we'll drop this too.

We're not dropping the environment variable / feature ever.  The
problem is that this was cargo-culted into a lot of code over the
years, and it does reduce the security of libguestfs on RHEL.  We're
having an (ongoing) battle to remove this cargo-culting from CNV right
now.  I'm just not keen to add this line in new places, without at
least a comment saying this is a temporary hack, and not generally
recommended.

> This part won't be executed as part of automated distribution tests
> either, so occasional breakages are really unproblematic.
> 
> Do you see any further issue with it?
> 
> -- 
> Stefano

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,
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