Fixes #16330 - random and MAC name generators

[lzap]

With deacon gem as foreman core dependency, it is possible to implement naming discovered hosts via deacon's MAC address generator.

https://github.com/lzap/deacon

This makes a lot of sense because the name stays with server until decommission. It's a feature of deacon gem - same MAC maps to same name. See the README.

[theforeman-bot]

Issues: #16330

[lzap]

This is fun! It needs a small core PR: theforeman/foreman#5637

[ik5]

the tests breaks on me, the reason is that the ensure part is not part of a begin and not part of a method, but rather inside a block call.

It should be something like that:

...
  begin
   ...
  ensure
     Setting[:discovery_naming] = "Fact"
  end
end

[lzap]

Yeah, weird it looks like newer version of Ruby supports it, good catch Jenkins! Rebasing, I actually removed those, it's not necessary since Settings are fixture records. They are reset on every test.

[dLobatog]

Thanks, works pretty well @lzap . Can we get the discovery docs updated to include this?