{% set os_family = salt['grains.get']('os_family') %}
{% set join_domain = salt['pillar.get']('join-domain:credentials', {}) %}

  {%- if join_domain %}

   {% if os_family == 'Windows' %}

windows_domain_join:
  module.run:
    - name: system.join_domain
    - domain: {{ join_domain.domain_name }}
    - username: {{ join_domain.username }}
    - password: {{ join_domain.password }}
    - account_ou: {{ join_domain.account_ou }}
    - restart: True

   {% endif %}

With pillar values to sniff out like:

join-domain:
  credentials:
    domain_name: 'domain.com'
    username: 'svc_account_domain'
    password: 'thingsandstuff'
    account_ou: 'ou=Servers,dc=domain,dc=com'