At @marc-barry's demand, here a couple things that could make usage simpler.

dedicated command for initial setup & migrations

In the readme you give a command to setup the db: https://github.com/digitalocean/docker-shipit-engine#database-management

Would be great if this could be done in a single command handled by the entry point, e.g. docker run shipit setup, and possibly docker run shipit upgrade to run post upgrade.

pubsubstub might cause issues in this setup

Something that's a bit finicky with Shipit is the SSE connection handling. Long story short client will keep a long lived connection per stack page. These aren't very expensive, but if your Puma config is a bit too strict in term of threads, you can easily hold all thread.

The ideal setup is to have dedicated containers for handling the streaming endpoints, see: Shopify/shipit-engine#496 (comment) for more details. But that makes for a more complicated setup as you need a LB etc.

Let me know if you need more details on that.

Database

Maybe I misread, but it seems you are focusing on postgres, I guess it's fine, but I suppose MySQL could be supported as well (and is a much better tested solution with Shipit).

I'll update this issue if something else comes up.