Juju renders invalid netplan YAML for nameservers in IPv4/IPv6 dual-stack environment

[Frode Nordahl]

I have a MAAS server exposed to a dual-stack IPv4/IPv6 network set up to consume LXD as a pod for virtual machines.

To simplify things I have bound all charms in my deployment to an IPv4-only space.

However, I still have issues deploying due to Juju rendering invalid netplan YAML for nameservers.

Example YAML:
network:
  version: 2
  ethernets:
    eth0:
      match:
        macaddress: 00:16:3e:e0:cd:e6
      addresses:
      - 172.16.122.48/24
      gateway4: 172.16.122.1
      nameservers:
        search: [maas]
        addresses: [10.75.217.187, '2001:464f:c282:8::1', 'fe80::6057:26ff:fee2:2e0f%2']

# netplan apply
/etc/netplan/99-juju.yaml:12:20: Error in network definition: malformed address 'fe80::6057:26ff:fee2:2e0f%2', must be X.X.X.X or X:X:X:X:X:X:X:X
        addresses: [10.75.217.187, '2001:464f:c282:8::1', 'fe80::6057:26ff:fee2:2e0f%2']

# deployed host version
$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 20.04 LTS
Release: 20.04
Codename: focal

$ juju --version
2.9-beta1-groovy-amd64

MAAS version: 2.9.0~alpha1 (8587-g.7e9f618b4)

$ lxd --version
4.2

[Simon Déziel (sdeziel)]

Since the nameservers is defined under the eth0 device, having the "%2" is redundant IMHO. Dropping it makes it work.

[Joseph Phillips (manadart)]

Addressed by https://github.com/juju/juju/pull/13895.
Credit to Stéphane.