Support looking up Monitors through DNS #5102
Description
Describe the feature you'd like to have
A built in feature of Ceph is to use DNS SRV records to identify Monitors. It is currently not possible provide an empty configuration of Monitors and rely on DNS as suggested by the Ceph documentation.
What is the value to the end user? (why is it a priority?)
DNS record usage would enable dynamic reconfiguration for clients over time without having to reload their configuration. This is an obvious advantage over a strict list of Monitors in a ConfigMap that must be reloaded to take effect.
How will we know we have a good solution? (acceptance criteria)
This one is really simple, if you can change a Monitor behind the scenes, update the DNS SRV records to reflect the change, and clients gradually shift to reflect this new reality then it will be a wild success.
Additional context
I am not at all familiar with the code for this project but based on a cursory glance it seems straightforward to support this. The Mons function only looks to the ConfigMap today; it seems obvious that failing a listed array of Mons a DNS SRV lookup could be performed.
As per the Ceph documentation above the mon_dns_srv_name option should be respected, but honestly even if an initial version of support was just DNS search domain based that would be an incredible value add.