remove resolved settings from config when changed to absent

[TheMeier]

Pull Request (PR) description

When dns_stub_listener and dns_stub_listener_extra are changed from a value to undef they don't get removed from the config.

There is plenty more settings here that could use the same treatment I guess

This Pull Request (PR) fixes the following issues

Fixes #397

[traylenator]

The fear is that since undef is the default this is now an action.

It's probably okay with this parameter.

I always quite like yumrepo's explicit absent.

[TheMeier]

The fear is that since undef is the default this is now an action.

It's probably okay with this parameter.

I always quite like yumrepo's explicit absent.

I see you point. I can't follow your comparison to yumrepo here. These are class parameters, yumrepo is more
There is a couple of ways we could handle this:

• go with the path laid out in this MR and mark it breaking
• implement more logic with a custom function that could look something like this:

  $_dns_stub_listener = $dns_stub_listener ? {
    true    => 'yes',
    false   => 'no',
    default => $dns_stub_listener,
  }
  
  if ($_dns_stub_listener) {
    ini_setting { 'dns_stub_listener':
      ensure  => new_function($_dns_stub_listener),
      value   => $_dns_stub_listener,
      setting => 'DNSStubListener',
      section => 'Resolve',
      path    => '/etc/systemd/resolved.conf',
      notify  => Service['systemd-resolved'],
    }
  }
  

• embrace the breaking and do a major restructuring
  Remove all the

  if $manage_* {
    contain systemd::*
  }
  

  and change alle the subclasses marked @api private to be used directly by the user.
  This would have 2 benefits, less params in init.pp, move many test out of init_spec.rb
  That would be a drastic change, though. But I think it is worth considering.

[TheMeier]

Not sure about the custom function. Isn't it just:

if $dns_stub_listener =~ NotUndef {
  ini_setting { '':
    ensure  => 'present',
    value   => $_dns_stub_listener,
    setting => 'DNSStubListener',
    section => 'Resolve',
    path    => '/etc/systemd/resolved.conf',
    notify  => Service['systemd-resolved'],
  }
}

i.e default remains as do nothing and set if set to which ever ?

But wasn't the whole point to find a way to set ensure => 'absent'. The idea was that one can set $dns_stub_listener == 'absent' and only in that case the ensure would be set to absent

[TheMeier]

@traylenator I have changed the code for an alternative solution... please have another look

[ekohl]

The commit message and PR description no longer match the actual code. Would you mind fixing that up to avoid confusion in the future?

[ekohl]

Small nits, but overall 👍

[ekohl]

Suggested change

	Optional[Variant[Boolean,Enum['udp','tcp','absent']]] $dns_stub_listener = undef,
	Optional[Variant[Boolean,Enum['udp','tcp','absent']]] $dns_stub_listener = undef,

[ekohl]

For a bit more readable type you can consider this:

Suggested change

	Optional[Variant[Array[String[1]],Enum['absent']]] $dns_stub_listener_extra = undef,
	Variant[Undef, Array[String[1]], Enum['absent']] $dns_stub_listener_extra = undef,