web_stack.rb

require 'augeas'

Facter.add(:web_stack) do
  aug = Augeas.open()

  setcode do
    ps = Facter::Util::Resolution.exec('ps axuww')
    listen = []
    servernames = []
    if ps =~ /apache2/
      engine = 'apache'
      aug.match('/files/etc/apache2//directive[.=~regexp("listen", "i")]').each do |l|
        listen << aug.get("#{l}/arg")
      end
      aug.match('/files/etc/apache2//VirtualHost//directive[.=~regexp("servername", "i")]').each do |m|
        servernames << aug.get("#{m}/arg")
      end
    elsif ps =~ /httpd/
      engine = 'apache'
      aug.match('/files/etc/httpd//directive[.=~regexp("listen", "i")]').each do |l|
        listen << aug.get("#{l}/arg")
      end
      aug.match('/files/etc/httpd//VirtualHost//directive[.=~regexp("servername", "i")]').each do |m|
        servernames << aug.get("#{m}/arg")
      end
    elsif ps =~ /nginx/
      engine = 'nginx'
      aug.match('/files/etc/nginx//listen').each do |l|
        listen << aug.get(l).split.first.split(':')[1]
      end
      aug.match('/files/etc/nginx//server_name').each do |m|
        servernames << aug.get(m).split
      end
    end

    {
      'engine'      => engine,
      'listen'      => listen.uniq,
      'servernames' => servernames.flatten.uniq,
    }
  end
end