[RFE] Check monitor-count against units deployed before starting mon cluster

[Peter Jose De Sousa]

Hi,

Similar to https://bugs.launchpad.net/charm-ceph-mon/+bug/1784860, if a mon cluster of three units is deployed with the monitor-count configured to 1; each mon in that cluster will assume that is the leader and cause a three-way split-brain situation. [1]

This bug is to request a change to the logic which checks the monitor count against expected monitor count to prevent this scenario and aid the end-user in deploying the cluster successfully.

Many thanks,

Peter

[1] https://github.com/openstack/charm-ceph-mon/blob/ed7b94b135e8a2c22dcda8ad32c5a89d58259ab4/lib/charms_ceph/utils.py#L769-L795

[Peter Sabaini (peter-sabaini)]

Triage
Support the single-mon use case better: prevent multiple mons to join if monitor-count==1