OpenWhisk OpenStack deployment error

ansible.log

ansible-playbook -i environments/distributed provision_env_dist.yml

PLAY [create instances and hosts file] ***********************************************************************************************************************

TASK [Gathering Facts] ***************************************************************************************************************************************
Tuesday 06 March 2018  14:37:43 +0000 (0:00:00.041)       0:00:00.041 ********* 
ok: [ansible]

TASK [add header to hosts file] ******************************************************************************************************************************
Tuesday 06 March 2018  14:37:44 +0000 (0:00:00.854)       0:00:00.895 ********* 
ok: [ansible]

TASK [Create instances] **************************************************************************************************************************************
Tuesday 06 March 2018  14:37:45 +0000 (0:00:00.752)       0:00:01.648 ********* 
included: /home/ubuntu/openwhisk/ansible/boot_instances_dist.yml for ansible

TASK [set vars] **********************************************************************************************************************************************
Tuesday 06 March 2018  14:37:45 +0000 (0:00:00.045)       0:00:01.693 ********* 
fatal: [ansible]: FAILED! => {"failed": true, "msg": "the field 'args' has an invalid value, which appears to include a variable that is undefined. The error was: 'ansible.vars.unsafe_proxy.AnsibleUnsafeText object' has no attribute 'name'\n\nThe error appears to have been in '/home/ubuntu/openwhisk/ansible/boot_instances_dist.yml': line 4, column 3, but may\nbe elsewhere in the file depending on the exact syntax problem.\n\nThe offending line appears to be:\n\n# TODO, in \"with_instance\" loops, the \"instance\" variable that is passed in gets unset, look up the proper way to do nested loops\n- name: set vars\n  ^ here\n"}

the field 'args' has an invalid value, which appears to include a variable
that is undefined. The error was: 'ansible.vars.unsafe_proxy.AnsibleUnsafeText
object' has no attribute 'name'  The error appears to have been in
'/home/ubuntu/openwhisk/ansible/boot_instances_dist.yml': line 4, column 3, but
may be elsewhere in the file depending on the exact syntax problem.  The
offending line appears to be:  # TODO, in "with_instance" loops, the "instance"
variable that is passed in gets unset, look up the proper way to do nested loops
- name: set vars   ^ here 

PLAY RECAP ***************************************************************************************************************************************************
ansible                    : ok=3    changed=0    unreachable=0    failed=1   

Tuesday 06 March 2018  14:37:45 +0000 (0:00:00.111)       0:00:01.804 ********* 
=============================================================================== 
Gathering Facts --------------------------------------------------------- 0.85s
add header to hosts file ------------------------------------------------ 0.75s
set vars ---------------------------------------------------------------- 0.11s
Create instances -------------------------------------------------------- 0.05s