I tried this a few months ago. Many features were missing then. I couldn't set up backups, and connect directly to `psql`. It was such a pain. I don't know if they've addressed those issues yet. It'd be a hard sell for me to store a database system for a production app in a Docker image.
Just a note about directly managing Postgres here: we launched Postgres like, a minute ago (a couple months in normal people time). For a pretty long time, you couldn't do any real persistent storage on a Fly instance; we were still mostly targeting edge applications, where people slice components of their apps off to run closer to the edge.
I think it's safe to say that while we still love edge apps and are committed to them long term, we've switched gears towards full-stack applications (that is, we've gotten a lot more ambitious about what we want to be a good platform for). So this stuff is shaping up pretty quickly.
Postgres (and volume support) happened at about the same time as private networking did (Postgres was our first internal application for private networks). In January, we started doing user-mode WireGuard, so that `flyctl` runs its own TCP/IP stack and speaks WireGuard directly, without involving the OS (so you don't need root to use it). User-mode WireGuard gave us `flyctl ssh console`, and is also the way we do direct `psql`. There's more stuff in that vein coming; hopefully, it's gotten a lot easier to manage Postgres as `flyctl` has gotten more capable.
Where we want to be is for it to be trivial to run something like Postico.app to talk to a Fly Postgres database. You can do that now, but it's not yet _totally_ trivial. Hopefully you can sort of look at `flyctl` (it's open source) and see how that'll work.
It's better, but still beta. We handle backups and you can connect directly to psql. We also added migration support as part of app releases. The global distribution feature, though, works with any database, not just our postgres.
Between you and me, we tried really hard not to build a Postgres service. We're committed now, it's gonna be good. For future DBs we plan to get big enough that people like Timescale to ship their products on Fly infrastructure.
You could run your own PG by modifying that app. Right now we're calling it "automated" and not managed, though. All alerts about health and other issues go straight to customers, we don't have DBAs that will touch these things yet.
