containers with different ubuntu release than the host?

[Andreas Hasenack]

juju-core-1.17.7

Hi,

should it be possible to create containers (lxc) with a different
ubuntu release than the host?

For example, I have a precise bootstrap node, and I do this:

juju deploy cs:trusty/ubuntu --to lxc:0

I logged in on that node and saw that juju called lxc-create with -r precise:

14857 ?        Ssl    1:37 /var/lib/juju/tools/machine-0/jujud machine
--data-dir /var/lib/juju --machine-id 0 --debug
16318 ?        S      0:00  \_ lxc-create -n juju-machine-0-lxc-0 -t
ubuntu-cloud -f /var/lib/juju/containers/juju-machine-0-lxc-0/lxc.conf
-- --debug --userdata
/var/lib/juju/containers/juju-machine-0-lxc-0/cloud-init --hostid
juju-machine-0-lxc-0 -r precise

So it ended up creating a precise container, not trusty. Is this
expected? If yes, shouldn't it error out instead of silently deploying
a different ubuntu distribution than what I asked?

I suppose that with kernel differences it's not guaranteed that the
services in the container will run on the kernel of the host if they
are too different, but that's "my problem".