Comment 2 for bug 800856

Scott,

what most people do is look at /proc/1/cgroup and see whether it is '/'.

Since lxc and libvirt both tell init whether it is in a container, you can also create an upstart job like:

description "track if this is lxc instance"

start on startup

env container
env LIBVIRT_LXC_UUID

pre-start script
        if [ -z $container ]; then
                if [ -z $LIBVIRT_LXC_UUID ]; then
                        stop
                        exit 0
                fi
        fi
end script

Then if, after boot, 'status islxc' shows

 islxc start/running

you know you're in a container.