Comment 3 for bug 1816442

I've reproduced it as:
unable to parse addrs in '10.0.8.129:6789 10.0.8.169:6789 10.0.8.188:6789:6789'

More details on steps:

## deploy ceph cluster
$ juju deploy --series bionic ceph-mon -n 3
Located charm "cs:ceph-mon-32".
Deploying charm "cs:ceph-mon-32".

$ juju config ceph-mon auth-supported=none

$ juju deploy --series bionic ceph-osd -n 3
Located charm "cs:ceph-osd-276".
Deploying charm "cs:ceph-osd-276".

$ juju config ceph-osd osd-devices=/srv/ceph
$ juju add-relation ceph-osd:mon ceph-mon:osd

$ juju wait -w

## ceph-proxy
$ juju deploy --series bionic ceph-proxy
Located charm "cs:ceph-proxy-17".
Deploying charm "cs:ceph-proxy-17".

$ juju config ceph-proxy auth-supported=none

$ juju config ceph-proxy fsid=$(juju run --unit ceph-mon/0 -- leader-get fsid)
$ juju config ceph-proxy fsid
-> bc8a8a36-3389-11e9-b320-00163ebb364a

$ juju config ceph-proxy admin-key=$(juju run --unit ceph-mon/0 -- leader-get monitor-secret)
$ juju config ceph-proxy admin-key
-> AQCDwWpcswHFMhAA/Jf9ME6pYq1a5e0jfH3Paw==

$ juju config ceph-proxy monitor-hosts="$(juju run --unit ceph-mon/0 -- grep '^mon host' /etc/ceph/ceph.conf | awk -F '= ' '{print $2}')"
$ juju config ceph-proxy monitor-hosts
-> 10.0.8.128:6789 10.0.8.167:6789 10.0.8.171:6789

## gnocchi and dependencies
$ juju deploy --series bionic gnocchi
Located charm "cs:gnocchi-16".
Deploying charm "cs:gnocchi-16".

$ juju deploy --series bionic keystone
$ juju deploy --series bionic percona-cluster mysql
$ juju deploy --series bionic memcached

$ juju add-relation gnocchi mysql
$ juju add-relation keystone mysql
$ juju add-relation gnocchi keystone
$ juju add-relation gnocchi memcached

$ juju ssh gnocchi/0 -- sudo cat /etc/ceph/ceph.conf | grep 'mon host'
mon host = 10.0.8.129:6789 10.0.8.169:6789 10.0.8.188:6789:6789

-> :6789:6789 is added