Custom ipaddress fact that ignores Docker (and other) interfaces

ipaddress.rb

# The builtin ipaddress fact is very naive and will pick the IP address of the
# first (alphabetically) interface. This fact changes that behavior and only
# grabs the IP off an interface matching /^(eth|bond|vlan)\d/. This excludes
# interfaces types such as TUN, bridges, and Docker.
Facter.add("ipaddress") do
  has_weight 100
  setcode do
    # This allows the fact to work from the commandline
    begin
      Facter.interfaces
    rescue
      Facter.loadfacts()
    end
    ipaddress = nil
    facts = []
    # Iterate over interfaces and add the fact with their IP address to the list to check
    interfaces = Facter.value('interfaces').split(",")
    interfaces.each do |interface|
      # Skip if it's not a "real" network interface
      if ! interface.match(/^(eth|bond|vlan)\d/)
        next
      end
      facts.push('ipaddress_' + interface.downcase)
    end
    facts.each do |fact|
      ipaddr = Facter.value(fact)
      if ipaddr.nil? || ipaddr == '127.0.0.1'
        next
      end
      ipaddress = ipaddr
      # Stop looking once we find a good address
      break
    end
    ipaddress
  end
end