Fixes #36548 - Avoid parsing interfaces with shared MACs

[ekohl]

In Azure it is possible to see the same interface share the same MAC address. Foreman wants to identify an interface by its MAC address, and doesn't handle it.

This patch makes parse_interfaces? take duplicate MAC addresses into account and ignores them. While it's not pretty, it at least allows other facts to be imported.

At the moment it's completely untested, but allows me to share the concept easier then describing it.

[theforeman-bot]

Issues: #36548

[ekohl]

@nofaralfasi would you mind reviewing this?

[ekohl]

The tests are failing because in test/static_fixtures/facts/facts_with_certname.json there's a host where the bridge has the same MAC as the interface as well as various VLANs. I think this is fairly common so I'm not sure what to do with this now.

[ekohl]

While going over the original bug I realized that the issue wasn't the duplicate MAC but the duplicate interface names. I'll rewrite the PR.

[ekohl]

I've done some further analysis and I believe my initial impression that the duplicate mac was the problem was correct. Just where it went wrong.

I now thing this is the problem:

foreman/app/models/host/base.rb

Lines 195 to 200 in 6aac916

	changed_count = 0
	parser.interfaces.each do |name, attributes|
	iface = get_interface_scope(name, attributes).try(:first) || interface_class(name).new(:managed => false)
	# create or update existing interface
	changed_count += 1 if set_interface(attributes, name, iface)
	end

We can see in the actual code there's matching by mac address:

foreman/app/models/host/base.rb

Lines 455 to 481 in 6aac916

	def get_interface_scope(name, attributes, base = interfaces)
	case interface_class(name).to_s
	# we search bonds based on identifiers, e.g. ubuntu sets random MAC after each reboot se we can't
	# rely on mac
	when 'Nic::Bond', 'Nic::Bridge'
	base.where(:identifier => name)
	# for other interfaces we distinguish between virtual and physical interfaces
	# for virtual devices we don't check only mac address since it's not unique,
	# if we want to update the device it must have same identifier
	else
	begin
	macaddress = Net::Validations.normalize_mac(attributes[:macaddress])
	rescue Net::Validations::Error
	logger.debug "invalid mac during parsing: #{attributes[:macaddress]}"
	end
	mac_based = base.where(:mac => macaddress)
	if attributes[:virtual]
	mac_based.virtual.where(:identifier => name) || find_by_attached_mac(base, mac_based, identifier, attributes)
	elsif mac_based.physical.any?
	mac_based.physical
	elsif !managed
	# Unmanaged host's interfaces are just used for reporting, so overwrite based on identifier first
	base.where(:identifier => name)
	end
	end
	end

That is not correct.

[ekohl]

I pushed some commits that separate it out. @nofaralfasi had a question about the chef fact parser and that's now a separate commit. There's also one that improves docs because I had to understand what was going on.