Ansible play for debugging a whole load of useful variables. Might be an issue with one of the template filters on 2.2

dumpall.j2

Module Variables ("vars"):
--------------------------------
{{ vars | to_nice_json }} 

Environment Variables ("environment"):
--------------------------------
{{ environment | to_nice_json }} 

GROUP NAMES Variables ("group_names"):
--------------------------------
{{ group_names | to_nice_json }}

GROUPS Variables ("groups"):
--------------------------------
{{ groups | to_nice_json }}

HOST Variables ("hostvars"):
--------------------------------
{{ hostvars | to_nice_json }} 

main.yml

- name: Dump all vars
  action: template src=dumpall.j2 dest=/tmp/ansible.all