Just to clarify our process: DB migrations are part of code review, they run as a script, but we don't have that script run automatically as part of CD. We've been bit by enough migration surprises that we require someone watching and able to interrupt and cancel the migration if needed. But that's the extent of action required. Run this command, Ctrl-C if necessary. Definitely not YOLO'ing in a psql in prod.
That's a really good process that scales forever even if you have a good person for it. Once you want to have more people do it, I find it easier to have hard-coded timeouts that cancel and rollback if the migration will be locked. I've also done auto rollback in these cases.
