How to access ceph.conf variable from ceph-ansible play

There is a command 'ceph-conf' that can be used inside Ansible play to access sections in ceph.conf on a remote host.

# ceph-conf -c /etc/ceph/ceph.conf --lookup  "bluestore block wal size" -s osd
2147483648

Ref
====
http://docs.ceph.com/docs/master/man/8/ceph-conf/