I created a separate pull request (#54) which uses fan overlay networking instead and it looks like in this setup IP addresses of Juju controllers are somehow managed in an intelligent way (a change of an IP results in a change of juju settings). However, in the setup with fan overlay networking Sunbeam currently fails to bootstrap, so it looks like this one is the only way to go for now until the other one gets fixed.

I'm trying to parse the requirements in the doc aside from the fact that it's tricky to request users to run a DHCP server in a data center.

• 172.16.1.0/24 - dedicated network for Juju controllers on top of a LXD cluster and LXD hosts (3 physical hosts in the default multi-node scenario)
  • a DHCP server is outside of those 3 nodes, but on the L2 somewhere not managed by this doc nor Sunbeam
  • 172.16.1.101, .102, .103 are static IPs
  • 172.16.1.248, .249, .250 are assigned IP addresses by the DHCP server and to be written as static IPs by hand in the LXD containers. However, no static lease is set on the DHCP server side so those IPs could be used by somebody else at the same time
• Prepare machines section still assumes a shared network instead of a dedicated network so there are some inconsistencies at this point.
  

  canonical-openstack-docs/how-to/misc/bootstrap-highly-available-juju-controller-on-top-of-a-lxd-cluster.rst

  Lines 29 to 61 in 8b4cb97

  	Prepare machines
  	++++++++++++++++
  	All machines have to be configured first to use `bridges <https://ubuntu.com/server/docs/configuring-networks#bridging-multiple-interfaces>`_ instead of physical network interfaces on the Generic network.
  	For example, to prepare the *cloud-1* machine from the example configuration section, execute the following commands:
  	.. code-block :: text
  	sudo bash -c 'cat <<EOF > /etc/netplan/config.yaml
  	network:
  	bridges:
  	br0:
  	addresses:
  	- 172.16.1.101/24
  	interfaces:
  	- eno1
  	routes:
  	- to: default
  	via: 172.16.1.1
  	nameservers:
  	addresses:
  	- 8.8.8.8
  	search:
  	- example.com
  	ethernets:
  	eno1:
  	set-name: eno1
  	eno2:
  	set-name: eno2
  	version: 2
  	EOF'
  	sudo netplan apply