defaults.yml

# data structure 
galera_client_apt_repo_url: "http://mirror.rackspace.com/mariadb/repo/5.5/ubuntu"
galera_client_apt_repo:
  repo: "deb {{ galera_client_apt_repo_url }} {{ ansible_distribution_release }} main"
  state: "present"
  url: "{{ galera_client_apt_repo_url }}"
  version: "5.1.41-3ubuntu12.7"
  origin_priority: 500
  release_priority: 510
  version_priority: 520

pin.pref.j2

# {{ ansible_managed }}

{% if galera_client_apt_repo.url is defined %}
Package: {{ galera_client_apt_repo.package }}
Pin: origin {{ galera_client_apt_repo.url | netloc }}
Pin-Priority: {{ galera_client_apt_repo.origin_priority | default("900") }}
{% endif %}

{% if galera_client_apt_repo.release is defined %}
Package: {{ galera_client_apt_repo.package }}
Pin: release o={{ galera_client_apt_repo.release }}
Pin-Priority: {{ galera_client_apt_repo.release_priority | default("900") }}
{% endif %}

Package: {{ galera_client_apt_repo.package }}
Pin: version {{ galera_client_apt_repo.version }}
Pin-Priority: {{ galera_client_apt_repo.version_priority | default("900") }}