Possible to install 32-bit LXC container in 64-bit host with multilib support?

Question

Is it possible to run a 32-bit LXC container (i.e. x86_32-based) on a 64-bit host (i.e. x86_64-based)?

1. Does it work at all?
2. What precautions may I have to take to make this work?

My kernel would be a 3.19 or newer.

Answer 1

Using Ubuntu Trusty 14.04, kernel: 4.2.0-36-generic #42~14.04.1-Ubuntu, lxc: 1.0.8-0ubuntu0.3 I was able to run a 32bit container in 64bit host.

Running the following cmd: lxc-create -n test -t /usr/share/lxc/templates/lxc-download

Giving these answers:

Distribution:  ubuntu
Release: trusty
Architecture: i386

The config diff is very minimal: lxc.arch = x86 vs lxc.arch = x86_64

Then simply starting it per usual: lxc-start -n test

Confirmed the OS thought the arch was 32bit

root@host:~# uname -a
Linux host 4.2.0-36-generic #42~14.04.1-Ubuntu SMP Fri May 13 17:27:22 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux
root@host:~# lxc-attach -n test
groups: cannot find name for group ID 111
root@container:~# uname -a
Linux distro 4.2.0-36-generic #42~14.04.1-Ubuntu SMP Fri May 13 17:27:22 UTC 2016 i686 GNU/Linux

I think the groups warning is something in my setup, either way it works!

There is a note in the Wiki to use linux32 to emulate 32bit. I don't think its needed.

linux32 lxc-create -n myvm -t debian-wheezy