it would be really useful to be able to make i386 lxc containers on a amd64 machine

twb says he's done it with the template at http://paste.debian.net/120603/

the lxc lucid template seems <this> close to being able to do i386 easily. The install_ubuntu() function sets arch from $(arch) without allowing a user supplied override.

This patch is a bit crude but does the job: using it I built a container and it works, though the arch is reported quirkily ;)
sudo arch=i386 lxc-create -n lucid-test-lp -t lucid-lp -f /etc/lxc/local.conf
sudo lxc-start -n lucid-test-lp
root@lucid-test-lp:~# arch
x86_64
root@lucid-test-lp:~# dpkg --print-architecture
i386

I've sent a patch upstream to add '-a i386' as a command line argument to the template. I will make a few more changes and then push a package to ppa while waiting for upstream to pull in the patch, after which a new release will end up in oneiric (which we can then backport).

Patches are here:

http://sourceforge.net/mailarchive/forum.php?thread_name=20110622140928.GA12177%40mail.hallyn.com&forum_name=lxc-users

http://sourceforge.net/mailarchive/forum.php?thread_name=20110622181733.GA17756%40mail.hallyn.com&forum_name=lxc-users

With these, I can do:

lxc-create -t ubuntu -n n1 -f /etc/lxc.conf -- -r natty -a i386 -b serge

to create an i386 natty-based container called n1, with /home/serge bind-mounted in.

note that my example left uname -m / arch unaltered and this will confuse some apps; linux32 /init/sbin rather than just /init/sbin should address that.

Thanks. The lxc package in ppa:serge-hallyn/lxc-natty, with the source
at https://code.launchpad.net/~serge-hallyn/ubuntu/oneiric/lxc/update-templates
has the rest of the fix, which just amounted to puttings 'lxc.arch' in the
config.

This bug was fixed in the package lxc - 0.7.4.2-0.3ubuntu1

---------------
lxc (0.7.4.2-0.3ubuntu1) oneiric; urgency=low

  * Sync upstream 0.7.4.2
  * Add diff up to git head.
    - Fix interaction with cgroups-bin (LP: #784093)
    - Fix arch support to create i386 containers on amd64 (LP: #798476)
    - Support a bind-mounted $HOME with template (LP: #800482)
  * add debootstrap to Recommends (LP: #803745)
  * debian/patchs updates:
    - refresh 0002-disable-debian-checkroot-script.patch
    - drop:
      * 0004-add-ubuntu-mirrors.patch
      * 0005-add-netbase-to-templates.patch
      * 0006-fix-template-syntax-error.patch
      * 0007-natty-template-install-lxcguest.patch
      * 0010-templates-use-dpkg.patch
    - renamed and updated:
      * 0008-add-arm-to-supported-archs.patch to
        0004-add-arm-to-supported-archs.patch
      * 0009-templates-dont-use-devpts-in-fstab to
        0005-dont-use-devpts-in-fstab
      * 0011-templates-allow-fuse.patch to
        0006-templates-allow-fuse.patch
  * remove unused debian/lxc-start.sh
  * include autoreconf.mk to force Makefile.in to be rebuilt
  * Remaining changes over debian:
    - add lxcguest package
    - debian/control
      * keep docbook-utils in Build-Depends
    - lxc.default: add commented example MIRROR
 -- Serge Hallyn <email address hidden> Thu, 07 Jul 2011 13:53:52 -0500

re this command line -
lxc-create -t ubuntu -n n1 -f /etc/lxc.conf -- -r natty -a i386 -b serge

-b probably wants to support abs paths, for flexability.

The seems reasonable - do you think it would be safe to say that if the argument starts with / it is a path, and, if not, then it is a username?

Excerpts from Serge Hallyn's message of Tue Jul 19 12:05:52 UTC 2011:
> The seems reasonable - do you think it would be safe to say that if the
> argument starts with / it is a path, and, if not, then it is a username?

What about

./foo

?

Quoting Clint Byrum (<email address hidden>):
> Excerpts from Serge Hallyn's message of Tue Jul 19 12:05:52 UTC 2011:
> > The seems reasonable - do you think it would be safe to say that if the
> > argument starts with / it is a path, and, if not, then it is a username?
>
> What about
>
> ./foo
>
>
> ?

"Don't do that."

But that's why I asked. If you prefer we can add a new switch for
path bindmounting (as opposed to user binding).

-serge