Cluster formation coordinator

[kjnilsson]

To safely grow and shrink clusters it may be good to provide a coordinator process as part of the ra application that ensures the correct nodes for any configured ra clusters are running and cluster nodes are started in a safe manner that minimises chances of "split" clusters.

This is, naturally, a consensus problem in itself so one question that may need answering as part of this task is - who coordinates the coordinator?

[dgmcguire]

would it be possible to use a static cluster on init (as the docs are doing) and then for dynamic joins/departures have the nodes wanting to join/leave first ask the raft cluster if they can join/leave and getting consensus before doing so?

[kjnilsson]

I think after all these years we've found that there isn't a single suitable solution for this.