Patch a machine to use lxcbr0 in bridge mode and assign a static ip to the container

lxc-clone-static-ip.sh

#!/bin/bash
 
/usr/bin/lxc-clone.real $@
RET=$?

# hostname will be of the form juju-FOO-machine-NUM
X=$(hostname | cut -d'-' -f4)  # here we grab NUM
# the 4th argument to lxc-clone is the new container's name that looks like juju-machine-NUM-lxc-CONTAINER_ID
COUNTER=$(echo $4 | cut -d'-' -f 5)
NEW_IP="10.5.${X}0.$(( $COUNTER + 20 ))"
 
echo "auto eth0
iface eth0 inet static
  address $NEW_IP
  netmask 255.255.0.0
  gateway 10.5.0.1
  dns-nameservers 10.5.0.2
  dns-search openstacklocal
" > /var/lib/lxc/$4/rootfs/etc/network/interfaces.d/eth0.cfg
 
exit $RET

lxcbr0.cfg

auto lxcbr0
iface lxcbr0 inet dhcp
	bridge_ports eth2
	bridge_fd 0
	bridge_maxwait 0

patch-machine.sh

#!/bin/bash -ex
# before using this you have to run 'juju add-machine lxc:NUM' to make juju prepare the template
# then just destroy the container with 'juju destroy-machine NUM/lxc/0' and then patch the machine
# with './patch-machine <NUM>'

MACHINE_ID=$1

# creating bridge on eth2
juju ssh $MACHINE_ID sudo service lxc-net stop
juju scp lxcbr0.cfg $MACHINE_ID:/tmp/
juju ssh $MACHINE_ID sudo cp /tmp/lxcbr0.cfg /etc/network/interfaces.d/
juju ssh $MACHINE_ID sudo ifup lxcbr0

# patching lxc-clone to use static ips
juju ssh $MACHINE_ID sudo mv /usr/bin/lxc-clone /usr/bin/lxc-clone.real
juju scp lxc-clone-static-ip $MACHINE_ID:/tmp/
juju ssh $MACHINE_ID sudo cp /tmp/lxc-clone-static-ip /usr/bin/
juju ssh $MACHINE_ID sudo ln -s /usr/bin/lxc-clone-static-ip /usr/bin/lxc-clone
juju ssh $MACHINE_ID sudo chmod +x /usr/bin/lxc-clone-static-ip
juju ssh $MACHINE_ID sudo service lxc-net start