since we're talking postgresql:
i recently started diving into postgresql and it seems to me that there is a patchwork of HA solutions (with patroni being the most feature-full) but no real multi-master solution for postgresql released under an open source license.
There's BDR (bi-directional replication) but apparently 2ndquadrant pulled it back under a proprietary license, am i right?
what's the current status of postgresql multi-master HA?
Not multi-master, but pg_auto_failover looks to be a very nice solution for HA, and one that is operationally simple to manage: https://github.com/citusdata/pg_auto_failover