with bridge/interface name too long netplan apply should fail

[Luca Cervigni]

IDEAL BEHAVIOUR: With interface or bridge name exceeding the maximum characters, `netplan apply` and not succeed and prompt the error.

ACTUAL BEHAVIOUR:
`netplan apply` works as if no errors though the network interfaces or bridges do not get created with errors in /var/log/syslog
The way to see that something is wrong is browsing /var/log/syslog

[Lukas Märdian (slyon)]

This is a valid point. Netplan IDs (i.e. interface names, for virtual interfaces) should be checked in the validation phase.

[Danilo Egea Gondolfo (danilogondolfo)]

I agree it should fail in such situations. But at this point, some people might have invalid interface names in their configuration, and as it's not failing it's not causing problems. If we switch the behavior to fail-by-default, we might cause real problems out there.

I propose we should emit a warning initially so users can be aware they have a problem in their configuration: https://github.com/canonical/netplan/pull/313

[Lukas Märdian (slyon)]

Released as of v0.106