[Errno 2] No such file or directory: '/etc/ceph/ceph.client.admin.keyring'

With expected-mon-count=3 deployment fails due to the following:

2018-03-14 08:04:35 INFO juju-log mon:2: Retrying 'add_keyring_to_ceph' 1 more times (delay=15)
2018-03-14 08:04:50 DEBUG mon-relation-changed creating /var/lib/ceph/tmp/juju-a67659-0-lxd-0.mon.keyring
2018-03-14 08:04:50 DEBUG mon-relation-changed added entity mon. auth auth(auid = 18446744073709551615 key=AQBc1qhaM/uoAxAAZYJ7WwqF0LwWklKWURmJcg== with 0 caps)
2018-03-14 08:04:50 DEBUG mon-relation-changed '/var/lib/ceph/mon/ceph-juju-a67659-0-lxd-0' already exists and is not empty: monitor may already exist
2018-03-14 08:04:53 DEBUG mon-relation-changed Traceback (most recent call last):
2018-03-14 08:04:53 DEBUG mon-relation-changed File "/var/lib/juju/agents/unit-ceph-mon-0/charm/hooks/mon-relation-changed", line 725, in <module>
2018-03-14 08:04:53 DEBUG mon-relation-changed hooks.execute(sys.argv)
2018-03-14 08:04:53 DEBUG mon-relation-changed File "/var/lib/juju/agents/unit-ceph-mon-0/charm/hooks/charmhelpers/core/hookenv.py", line 800, in execute
2018-03-14 08:04:53 DEBUG mon-relation-changed self._hooks[hook_name]()
2018-03-14 08:04:53 DEBUG mon-relation-changed File "/var/lib/juju/agents/unit-ceph-mon-0/charm/hooks/mon-relation-changed", line 356, in mon_relation
2018-03-14 08:04:53 DEBUG mon-relation-changed ceph.bootstrap_monitor_cluster(leader_get('monitor-secret'))
2018-03-14 08:04:53 DEBUG mon-relation-changed File "lib/ceph/utils.py", line 1323, in bootstrap_monitor_cluster
2018-03-14 08:04:53 DEBUG mon-relation-changed init_marker)
2018-03-14 08:04:53 DEBUG mon-relation-changed File "/var/lib/juju/agents/unit-ceph-mon-0/charm/hooks/charmhelpers/core/decorators.py", line 40, in _retry_on_exception_inner_2
2018-03-14 08:04:53 DEBUG mon-relation-changed return f(*args, **kwargs)
2018-03-14 08:04:53 DEBUG mon-relation-changed File "lib/ceph/utils.py", line 1360, in add_keyring_to_ceph
2018-03-14 08:04:53 DEBUG mon-relation-changed osstat = os.stat("/etc/ceph/ceph.client.admin.keyring")
2018-03-14 08:04:53 DEBUG mon-relation-changed FileNotFoundError: [Errno 2] No such file or directory: '/etc/ceph/ceph.client.admin.keyring'
2018-03-14 08:04:54 ERROR juju.worker.uniter.operation runhook.go:114 hook "mon-relation-changed" failed: exit status 1