common.yaml

applications:
    app::core::instance:
        '01':
            index: '01'
        '02':
            index: '02'

hiera_resources.rb

Puppet::Parser::Functions.newfunction(:hiera_resources, :type => :statement) do |args|
  raise Puppet::Error, "hiera_resources requires 1 argument; got #{args.length}" if args.length != 1
  apps = function_hiera_hash(args[0], {})
  apps.each do |res_type, resources|
    function_create_resources(res_type, resources)
  end
end

init.rb

hostclass applications do
  apps = function_hiera_hash('applications')
  apps.each do |res_type, resources|
    function_create_resources(res_type, resources)
  end
end