Comment 8 for bug 2065700

With an educated guess that Juju sorts subnets in numerical order, I tried an explicit subnet as 10.0.123.0/24 (within 10.0.0.0/16 range to show up earlier than 10.1.0.0/16 as the default Calico range in microk8s).

The result is as expected. The original issue remains the same that Juju may use the /32 address from vxlan.calico. But Juju returns an address from the 10.0.123.0/24 range so it can work around the issue in one way.

In a real-life world, using 10.0.0.0/16 as the host subnet just for Juju and Sunbeam is practically impossible by eliminating 10.0.0.0/8 minus 10.0.0.0/16, 172.16.0.0/12 and 192.168.0.0/16 though.

$ juju spaces
Name Space ID Subnets
alpha 0 10.0.123.0/24
                 10.1.186.0/32
                 10.1.32.192/32

$ juju exec --unit microceph/0 -- network-get public
bind-addresses:
- mac-address: 52:54:00:51:00:99
  interface-name: enp1s0
  addresses:
  - hostname: ""
    value: 10.0.123.241
    cidr: 10.0.123.0/24
    address: 10.0.123.241
  macaddress: 52:54:00:51:00:99
  interfacename: enp1s0
- mac-address: 66:a8:66:69:8e:0f
  interface-name: vxlan.calico
  addresses:
  - hostname: ""
    value: 10.1.32.192
    cidr: 10.1.32.192/32
    address: 10.1.32.192
  macaddress: 66:a8:66:69:8e:0f
  interfacename: vxlan.calico
egress-subnets:
- 10.0.123.241/32
ingress-addresses:
- 10.0.123.241
- 10.1.32.192

$ sudo microceph status
MicroCeph deployment summary:
- sunbeam-1 (10.0.123.241)
  Services: mds, mgr, mon, osd
  Disks: 2
- sunbeam-2 (10.0.123.234)
  Services: mds, mgr, mon
  Disks: 0