Issue with `bamboo: create bamboo configuration` task

[colin-nolan]

TASK [bamboo : create bamboo configuration] ************************************************************************************************************************************************************************************************************************************
task path: /data/hgi-systems/ansible/roles/bamboo/tasks/main.yml:26
fatal: [hgs4f]: FAILED! => {"changed": false, "failed": true, "msg": "AnsibleUndefinedVariable: {% for host in groups['marathoners'] %}http://{{ hgi_username }}:{{ hgi_password }}@{{ hostvars[host]['ansible_fqdn'] }}:{{ marathon_http_port }}{% if not loop.last %},{% endif %}{% endfor %}: 'dict object' has no attribute 'ansible_fqdn'"}
...

(All hosts are affected)