Hi, the author of the blog post here. I don't have a precise number, but somewhere in the €800/mo region.

Is the decision not to use Patroni for HA Postgres in this case, so that you don’t add more complexity?

Yes. Plus, from reading database outage postmortems, I was not comfortable making the "do we failover now?" decision automatic. Think about the brownouts, where the primary is still up, but slow. Or it experiences intermittent packet loss.

I've automated the mechanics of the failover, but it still must be initiated manually.

That‘s a good decision! Developers nowadays fear a failing machine so much because it‘s happening more often on the cloud than dedicated servers. I wouldn‘t use automatic failover too. Cleaning up the mess can take hours and days, a small downtime of a few minutes/hours is better.

I‘ve seen one developer using telegram for ha-failover which is great! Just a message and the scripts are executed for a failover. You can do it in seconds without even being on a computer.

Project I relate to, doing switch to Patroni managed DB (first of many) right today, in like a 5 hours, I may share observations from almost first hand experience later, if you care.

The monthly Hetzner bill is €484.