Assigning to Paul since this is ceph-iscsi-ansible related.
OK - so this is an update to the hosts file saying I want 3 gateways, and then the admin doesn't update the group vars to provide 3 gateway ip's. This can be trapped and failed more gracefully.
fix applied and version 1.2 of the ceph-iscsi-ansible and ceph-iscsi-config available for QA testing from Brew.
please retest with 1.3 version
Verified in build: ceph-iscsi-ansible-1.5-1.el7test.noarch
Since the problem described in this bug report should be resolved in a recent advisory, it has been closed with a resolution of ERRATA. For information on the advisory, and where to find the updated files, follow the link below. If the solution does not work for you, open a new bug report. https://access.redhat.com/errata/RHBA-2016:2817