Your mongodb role should look something like this:
- name: MongoDB - Import public key
  apt_key:
    keyserver: hkp://keyserver.ubuntu.com:80
    id: EA312927
- name: MongoDB - Add repository
  apt_repository:
    filename: '/etc/apt/sources.list.d/mongodb-org-3.2.list'
    repo: 'deb http://repo.mongodb.org/apt/ubuntu trusty/mongodb-org/3.2 multiverse'
    state: present
    update_cache: yes
- name: MongoDB - Install MongoDB
  apt:
    name: mongodb-org
    state: present
    update_cache: yes
- name: MongoDB - Running state
  service:
    name: mongod
    state: started
Hope this helps!!
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Thanks!