Composing a VM with an IP address on its interface is in Auto Assign state after commissioning

I tried this on maas 2.6.2 and verified that the node commissions with the given static ip, the mode is auto and the ip goes away after it finishes commissioning.

ubuntu@OrangeBox100:~$ maas admin pod compose 13 hostname=vern1 cores=1 memory=1024 storage=5 interfaces="eth0:space=undefined,ip=172.27.100.100,mode=static"
Success.
Machine-readable output follows:
{
    "system_id": "73a8gy",
    "resource_uri": "/MAAS/api/2.0/machines/73a8gy/"
}
ubuntu@OrangeBox100:~$ systemid=73a8gy
ubuntu@OrangeBox100:~$ maas admin machine read $systemid | jq '{"status": .status_name, "boot_interface": .boot_interface.links[0] | {"mode": .mode, "ip_address": .ip_address}}'
{
  "status": "Commissioning",
  "boot_interface": {
    "mode": "auto",
    "ip_address": "172.27.100.100"
  }
}
ubuntu@OrangeBox100:~$ maas admin machine read $systemid | jq '{"status": .status_name, "boot_interface": .boot_interface.links[0] | {"mode": .mode, "ip_address": .ip_address}}'
{
  "status": "Ready",
  "boot_interface": {
    "mode": "auto",
    "ip_address": null
  }
}
ubuntu@OrangeBox100:~$ maas admin version read
Success.
Machine-readable output follows:
{"capabilities": ["networks-management", "static-ipaddresses", "ipv6-deployment-ubuntu", "devices-management", "storage-deployment-ubuntu", "network-deployment-ubuntu", "bridging-interface-ubuntu", "bridging-automatic-ubuntu", "authenticate-api"], "version": "2.6.2", "subversion": "7841-ga10625be3-0ubuntu1~19.10.1"}

I'm having this problem right now with maas snap 2.9.2.

I'm using "eth0:space=oam:ip=x.x.x.x" (as opposed to "eth0:space=oam,ip=x.x.x.x) but I don't think this makes a difference because the behavior I see is exactly the same as described (ip gets assigned, can be seen in the network config screen but after commissioning it goes away).

We are not blocked by this right now because static ip is not necessary in initial tests but it will become a problem soon.

Just mentioning that https://bugs.launchpad.net/maas/+bug/1883349 is a duplicate of this and there it mentions a workaround.

The issue here is that after composing the VM, we do a normal commissioning of the VM. That will autodetect the interface configuration and reset them to the default configuration, which is auto assign.

Given that we configure the interfaces fully on compose, we can probably get away with setting retain_network_configuration to True.

Or we could store the composed network configuration and use that when configuring networking after commissioning.