mac address parsing fails on specific mac addressess

[Qarion]

config snippet:
        ens8:
            addresses: [10.3.59.3/24]
            match:
                macaddress: 52:54:00:26:30:21
            set-name: ens8

when trying netplan try with this specific mac address I get an error(see bellow)
fortunately I was able to get a different mac address for the vm which did work with everything else in the config the same, but it seems mac address containing only numbers are parsed as a number instead of a string?

root@ubuntu:~# netplan try
Warning: Stopping systemd-networkd.service, but it can still be activated by:
  systemd-networkd.socket

An error occurred: 'int' object has no attribute 'lower'

Reverting.
Warning: Stopping systemd-networkd.service, but it can still be activated by:
  systemd-networkd.socket
Traceback (most recent call last):
  File "/usr/share/netplan/netplan/cli/commands/try_command.py", line 84, in command_try
    NetplanApply().command_apply(run_generate=True, sync=True, exit_on_error=False)
  File "/usr/share/netplan/netplan/cli/commands/apply.py", line 187, in command_apply
    changes = NetplanApply.process_link_changes(devices, config_manager)
  File "/usr/share/netplan/netplan/cli/commands/apply.py", line 283, in process_link_changes
    current_iface_name = utils.find_matching_iface(interfaces, match)
  File "/usr/share/netplan/netplan/cli/utils.py", line 199, in find_matching_iface
    matches = list(filter(lambda iface: is_interface_matching_macaddress(iface, match.get('macaddress')), matches))
  File "/usr/share/netplan/netplan/cli/utils.py", line 199, in <lambda>
    matches = list(filter(lambda iface: is_interface_matching_macaddress(iface, match.get('macaddress')), matches))
  File "/usr/share/netplan/netplan/cli/utils.py", line 187, in is_interface_matching_macaddress
    return match_mac.lower() == macaddress.lower()
AttributeError: 'int' object has no attribute 'lower'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/sbin/netplan", line 23, in <module>
    netplan.main()
  File "/usr/share/netplan/netplan/cli/core.py", line 50, in main
    self.run_command()
  File "/usr/share/netplan/netplan/cli/utils.py", line 257, in run_command
    self.func()
  File "/usr/share/netplan/netplan/cli/commands/try_command.py", line 66, in run
    self.run_command()
  File "/usr/share/netplan/netplan/cli/utils.py", line 257, in run_command
    self.func()
  File "/usr/share/netplan/netplan/cli/commands/try_command.py", line 95, in command_try
    self.revert()
  File "/usr/share/netplan/netplan/cli/commands/try_command.py", line 118, in revert
    NetplanApply().command_apply(run_generate=False, sync=True, exit_on_error=False)
  File "/usr/share/netplan/netplan/cli/commands/apply.py", line 187, in command_apply
    changes = NetplanApply.process_link_changes(devices, config_manager)
  File "/usr/share/netplan/netplan/cli/commands/apply.py", line 283, in process_link_changes
    current_iface_name = utils.find_matching_iface(interfaces, match)
  File "/usr/share/netplan/netplan/cli/utils.py", line 199, in find_matching_iface
    matches = list(filter(lambda iface: is_interface_matching_macaddress(iface, match.get('macaddress')), matches))
  File "/usr/share/netplan/netplan/cli/utils.py", line 199, in <lambda>
    matches = list(filter(lambda iface: is_interface_matching_macaddress(iface, match.get('macaddress')), matches))
  File "/usr/share/netplan/netplan/cli/utils.py", line 187, in is_interface_matching_macaddress
    return match_mac.lower() == macaddress.lower()
AttributeError: 'int' object has no attribute 'lower'

[Lukas Märdian (slyon)]

Netplan's configmanager.py uses a python YAML parser, which interpret MAC addresses, consisting of numbers only as integer, e.g.:

>>> import yaml
>>> yaml.safe_load('52:54:00:26:30:21')
41135135421

Please make sure to quote your value (i.e. macaddress: '52:54:00:26:30:21') to have it interpreted as a string.
The netplan CLI will eventually transition to another YAML parser (from libnetplan), which will do more specific input validation and will better handle situations like this.