Description of problem:
When a cluster is installed using "osd_auto_discovery" set to true,
the purge cluster fails.
If "osd_auto_dscovery" is true , the customer would not know which devices  have osd's
This could be a problem on large clusters.
Can we try for a mor eintelligent way of purging clusters?

PLAY [confirm whether user really meant to purge the cluster] ***************** 

GATHERING FACTS *************************************************************** 
ok: [localhost]

TASK: [exit playbook, if user did not mean to purge cluster] ****************** 
skipping: [localhost]

PLAY [stop ceph cluster] ****************************************************** 

GATHERING FACTS *************************************************************** 
ok: [magna058]
ok: [magna046]
ok: [magna052]

TASK: [check for a device list] *********************************************** 
failed: [magna046] => {"failed": true}
msg: OSD automatic discovery was detected, purge cluster does not support this scenario. If you want to purge the cluster, manually provide the list of devices in group_vars/osds using the devices variable.
failed: [magna052] => {"failed": true}
msg: OSD automatic discovery was detected, purge cluster does not support this scenario. If you want to purge the cluster, manually provide the list of devices in group_vars/osds using the devices variable.
failed: [magna058] => {"failed": true}
msg: OSD automatic discovery was detected, purge cluster does not support this scenario. If you want to purge the cluster, manually provide the list of devices in group_vars/osds using the devices variable.

FATAL: all hosts have already failed -- aborting

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

localhost                  : ok=1    changed=0    unreachable=0    failed=0   
magna046                   : ok=1    changed=0    unreachable=0    failed=1   
magna052                   : ok=1    changed=0    unreachable=0    failed=1   
magna058                   : ok=1    changed=0    unreachable=0    failed=1   



How reproducible:
Always