application fact

application.rb

# This custom fact will figure out which application
# a node belongs to by looking at the node's hostname
# and comparing that to a known list of applications.
#
# This fact relies on a naming convention where the
# first three letters of a node's hostname signify
# what application that node belongs to.
#
Facter.add(:application) do
  setcode do

    # This map is the list of applications and their
    # possible abbreviations that could be in a hostname.
    application_map = {
      'webserver' => [ 'web', 'www', 'iis' ],
      'remote'    => [ 'rem', 'rdp' ],
      'gitlab'    => [ 'git' ],
      'puppet'    => [ 'pup' ],
    }

    # Get the first 3 letters of the node's hostname, and
    # make sure it's lowercase.
    hostname = Facter.value(:hostname).downcase
    hostname_first_three = hostname[0..2]

    # Create an empty variable to store the final result.
    application = nil

    # Iterate through each element of the application_map
    # and see if the abbreviations match the first three
    # letters of a host's name. If it does match, save
    # the application name and stop searching for matches.
    application_map.each do | app_name, abbreviations |
      if abbreviations.include? hostname_first_three
        application = app_name
        break
      end
    end

    # Return the application name.
    # This will be nil (undef in Puppet) if a match isn't found.
    application

  end

end