===In node yaml file:===

modx_install:
  'domain5.tld':
     database_name: 'domain5'
     database_user: 'domain5'
     database_password: 'qwerty'
     modx_admin_username: 'adminuser33'
     modx_admin_password: 'qwerty12345678'


modx_install:
  - 'domain9.tld':
         database_name: 'domain9'
         database_user: 'domain9'
         database_password: 'qwerty'
         modx_admin_username: 'adminuser33'
         modx_admin_password: 'qwerty12345678'

===in manifests/site.pp ===

create_resources('modx::install', hiera('modx_install', {}))