installing ceph in ubuntu 18.04 ceph-osd charm went to error state

[vinaya]

juju status ceph-osd showing as below.

ceph-osd/0 error idle 0 10.110.86.15 hook failed: "config-changed"

source used: cloud:bionic-ussuri

Here is debug log

unit-ceph-osd-0: 08:11:06 DEBUG unit.ceph-osd/0.config-changed import ceph.utils as ceph
unit-ceph-osd-0: 08:11:06 DEBUG unit.ceph-osd/0.config-changed ModuleNotFoundError: No module named 'ceph.utils'
unit-ceph-osd-0: 08:11:06 ERROR juju.worker.uniter.operation hook "config-changed" (via explicit, bespoke hook script) failed: exit status 1