Bonded Interfaces with down links cause systemd-networkd-wait-online failure

[Firefishy]

With systemd version < 256 when bonded interfaces with 1 or more disconnected slave links the interface state is set to degraded-carrier. systemd-networkd-wait-online then waits and eventually fails with a timeout. This bug was corrected in systemd/systemd#27776

Ubuntu 22.04 and Debian 12 adding the following to the bond0.network fixes the issue:

[Link]
RequiredFamilyForOnline=ipv4
RequiredForOnline=degraded-carrier

RequiredFamilyForOnline is not available in Ubuntu 20.04

Affected systems include piasa

[Firefishy]

The default in systemd v256 is RequiredFamilyForOnline=any, RequiredForOnline=degraded-carrier on bonded links.

[tomhughes]

Actually since systemd/systemd#27776 (first in v254) a bond link will show as routable even if not all interfaces have carrier.

Also in v256 the default for RequiredForOnline is degraded-carrier but only if RequiredFamilyForOnline is any which it isn't by default.

That said the proposal here is probably the best option for versions before 254.

[tomhughes]

Fixed in openstreetmap/chef@5f5aedb.