In summary: I think the root cause is that the lxc container is not
set up the way sbuild expects.
The named directory becomes $self->get('Location') within sbuild; it's
a dummy value used when (as in this case) the chroot provider does not
have a way to access the within-chroot filesystem from outside it.
It is used in relatively few places. Searching for more of the error
message found a use in basesetup (in ChrootSetup.pm). It seems to try
to use it only if the `sbuild' group is not found in the chroot.
Looking at the code, sbuild expects various other preparatory things
to have been done to the chroot. It expects a /build directory, and
/var/lib/sbuild, and so on. I can't find any of this documented
anywhere.
Hopefully the following, observed in an schroot of mine, is helpful:
$ id sbuild
uid=120(sbuild) gid=124(sbuild) groups=124(sbuild)
$ find /build/ /var/lib/sbuild/ -ls
606209 4 drwxrws--- 2 sbuild sbuild 4096 Jun 3 2016 /build/
344285 4 drwxrws--- 3 sbuild sbuild 4096 Jun 3 2016
/var/lib/sbuild/
344838 4 -rw-rw-r-- 1 root sbuild 1417 Jun 3 2016
/var/lib/sbuild/package-checklist
344355 4 drwxrws--- 2 sbuild sbuild 4096 Jun 3 2016
/var/lib/sbuild/srcdep-lock
344721 4 -rw------- 1 root sbuild 117 Jun 3 2016
/var/lib/sbuild/apt.conf
$
Is there a script that someone could run in an existing
vm/container/whatever, to prepare it appropriately, before
snapshotting ?
Also, the error message seems poor.
I suggest the following approach:
* Break out the relevant bits of sbuild-createchroot into an
advertised script that can be run as root within the master
image (what schroot calls the source chroot).
* Replace calls to ->get('Location') with ->get_location($reason)
and make the latter fail if the access is not supported.
$reason will be an explanation of what schroot was trying to do.
So it will say something like
E: filesystem access to chroot not supported (wanted because: trying to
add sbuild group)
* In the longer term, the virt servers should have a way to edit
the master image. Then you could say sbuild --setup-the-thing
--autopkgtest-etc.
Thanks,
Ian.
--
Ian Jackson <ijack...@chiark.greenend.org.uk> These opinions are my own.
If I emailed you from an address @fyvzl.net or @evade.org.uk, that is
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