[keypusher]

If you are running multiple copies of postgres on a single node, then you have not significantly improved the resiliency of your database to failure, and it still does not solve the state transition problem. What happens when the primary database fails (or the node dies)? Whether it is on this node or another node, you need to have a replica (sync or async) that you can fail over to, preferably in an automated way. Docker swarm is not equipped to handle these transitions for you, at which point you are just running your database in Docker, with no real benefit over running it on actual hardware or a VM, and with significant added complexity.