Description of problem:
======================
Document:-
https://access.qa.redhat.com/documentation/en/red-hat-ceph-storage/version-2/installation-guide-for-red-hat-enterprise-linux/#installing_red_hat_ceph_storage_using_ansible


'3.2. CONFIGURE CEPH GLOBAL SETTINGS' has list of variable that needs to be changed in 'all' file.

Please modify that section and add 3 more variables - 
1. ceph_stable
2. journal_size
3.  "public_network"

If we dont set value for this variables installation fails as below:-

1.

If not set - "ceph_stable"

TASK: [ceph.ceph-common | configure cluster name] ***************************** 
failed: [magna004] => {"failed": true, "rc": 257}
msg: Destination /etc/sysconfig/ceph does not exist !
failed: [magna005] => {"failed": true, "rc": 257}
msg: Destination /etc/sysconfig/ceph does not exist !
failed: [magna012] => {"failed": true, "rc": 257}
msg: Destination /etc/sysconfig/ceph does not exist !

FATAL: all hosts have already failed -- aborting

PLAY RECAP ******************************************************************** 
           to retry, use: --limit @/root/site.retry

magna004                   : ok=41   changed=5    unreachable=0    failed=1   
magna005                   : ok=41   changed=4    unreachable=0    failed=1   
magna012                   : ok=41   changed=4    unreachable=0    failed=1   

2."journal_size" not set than

TASK: [ceph.ceph-common | make sure journal_size configured] ****************** 
failed: [magna015] => {"failed": true}
msg: journal_size must be configured. See http://ceph.com/docs/master/rados/configuration/osd-config-ref/
failed: [magna016] => {"failed": true}
msg: journal_size must be configured. See http://ceph.com/docs/master/rados/configuration/osd-config-ref/
failed: [magna019] => {"failed": true}
msg: journal_size must be configured. See http://ceph.com/docs/master/rados/configuration/osd-config-ref/

FATAL: all hosts have already failed -- aborting


3.  "public_network" not set than

TASK: [ceph.ceph-common | make sure cluster_network configured] *************** 
failed: [magna015] => {"failed": true}
msg: cluster_network must be configured. Ceph replication network
failed: [magna016] => {"failed": true}
msg: cluster_network must be configured. Ceph replication network
failed: [magna019] => {"failed": true}
msg: cluster_network must be configured. Ceph replication network

FATAL: all hosts have already failed -- aborting



Version-Release number of selected component (if applicable):
==============================================================
ceph-10.1.0-1.el7cp.x86_64
ceph-ansible-1.0.3-1.el7.noarch


How reproducible:
===================
always


Steps to Reproduce:
1. follow document 
https://access.qa.redhat.com/documentation/en/red-hat-ceph-storage/version-2/installation-guide-for-red-hat-enterprise-linux/#installing_red_hat_ceph_storage_using_ansible