Description of problem:
rgw service fails to start on ubuntu during install with ceph-ansible
the librgw is installed.

Version-Release number of selected component (if applicable):
ceph-ansible: 1.0.5-12.el7scon.noarch
ceph: 10.2.1-2redhat1xenial

How reproducible:
Always

Steps to Reproduce:
1. define [rgws] in the hosts file.
2. start install using ansible-playbook command.
3. the playbook fails

Actual results:
playbook fails to start rgw

Expected results:
rgw should be installed correctly

Additional info:

TASK: [ceph-rgw | check if rgw is started] ************************************ 
ok: [magna052]

TASK: [ceph-rgw | start rgw] ************************************************** 
skipping: [magna052]

TASK: [ceph-rgw | start and add that the rados gateway service to the init sequence (ubuntu)] *** 
skipping: [magna052]

TASK: [ceph-rgw | start rgw on red hat (before or on infernalis)] ************* 
skipping: [magna052]

TASK: [ceph-rgw | enable systemd unit file for rgw instance (for or after infernalis)] *** 
ok: [magna052]

TASK: [ceph-rgw | start rgw with systemd (for or after infernalis)] *********** 
failed: [magna052] => {"failed": true}
msg: Error when trying to enable ceph-radosgw: rc=1 Failed to execute operation: No such file or directory


FATAL: all hosts have already failed -- aborting

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

magna009                   : ok=159  changed=22   unreachable=0    failed=0   
magna052                   : ok=222  changed=12   unreachable=0    failed=1   
magna058                   : ok=155  changed=9    unreachable=0    failed=0


root@magna052:~# dpkg -l | grep gw   
ii  libhogweed4:amd64                    3.2-1                                    amd64        low level cryptographic library (public-key cryptos)
ii  librgw2                              10.2.1-2redhat1xenial                    amd64        RADOS Gateway client library
root@magna052:~# 


root@magna052:/var/lib/ceph/radosgw/ceph-rgw.magna052# ls
done  keyring  upstart
root@magna052:/var/lib/ceph/radosgw/ceph-rgw.magna052# 
root@magna052:/var/lib/ceph/radosgw/ceph-rgw.magna052# cat keyring 
[client.rgw.magna052]
	key = AQDhuzpXfy/qKBAACEZI9ikzY/cifi54YZ415Q==

Unable to see any logs .