Description of problem:

https://bugzilla.redhat.com/show_bug.cgi?id=1576001 implied adding a new parameter (kuryr_openstack_public_net_id) which is mandatory. The parameter must be specified in OpenStack configuration file (all.yml), but if not added the playbook fails.

Adding a check for the parameter existence in prerequisites stage would prevent the install playbook from failing, and getting the error before deploying the Openshift cluster. It will fail at the very beginning of the playbook, when checking the prerequisites.

Version-Release number of the following components:
rpm -q openshift-ansible
openshift-ansible-3.10.0-0.46.0.git.0.85c3afd.el7.noarch

rpm -q ansible
ansible-2.4.3.0-1.el7ae.noarch

ansible --version
ansible 2.4.3.0
  config file = /etc/ansible/ansible.cfg
  configured module search path = [u'/home/cloud-user/.ansible/plugins/modules', u'/usr/share/ansible/plugins/modules']
  ansible python module location = /usr/lib/python2.7/site-packages/ansible
  executable location = /usr/bin/ansible
  python version = 2.7.5 (default, Feb  9 2018, 09:51:13) [GCC 4.8.5 20150623 (Red Hat 4.8.5-28)]

How reproducible: always

Steps to Reproduce:
1. Run Openshift-on-Openstack playbook without setting the kuryr_openstack_public_net_id

Actual results:
TASK [kuryr : Create kuryr ConfigMap manifest] ********************************************************************************************************************************************************************
fatal: [master-0.openshift.example.com]: FAILED! => {"changed": false, "msg": "AnsibleUndefinedVariable: 'kuryr_openstack_public_net_id' is undefined"}

  1. Hosts:    master-0.openshift.example.com
     Play:     Configure masters
     Task:     Create kuryr ConfigMap manifest
     Message:  AnsibleUndefinedVariable: 'kuryr_openstack_public_net_id' is undefined

Expected results:
Failure in prerequisites playbook, not in install playbook.