fix(db): mechanism for db provisioning/migrations (PXP-7918)

[williamhaley]

Jira Ticket: PXP-7918

New Features

• Meta-migrations mechanism to orchestrate new DBs, users, and other non-application level migrations

Bug Fixes

• Resolves an issue for existing users who would be adding MDS to their stack

[williamhaley]

This all feels a bit hokey, but (after some searching) I found there is no mainline way out-of-the-box to set up a simple "run this script at startup" process for postgres' docker image so I created a custom entrypoint/command here to accomplish the task of setting up DBs and doing other DB work to orchestrate data as needed.

[williamhaley]

This relates to running the script after the init scripts but before the DB is accessible to other apps on the network. That distinction is significant because our apps (mostly) wait for the DB to be available and once it's online they get to work.

[williamhaley]

Official maintainers have considered that users like us may want this sort of behavior where we can run migrations or other scripts against Postgres and have done some work that allows us to hook into their entrypoint and create our own for this sort of behavior.

[williamhaley]

I will happily take in any/all suggestions for other ways to go about this sort of thing and re-think the implementation if this doesn't seem ideal. 🙇 These are some alternatives I was thinking about...

1. A manual process. Give users explicit instructions for adding new DBs, users, or other migrations we need them to do

   A bit clunky, and requires maintaining documentation

2. Alembic or similar mechanism to run meta/orchestration migrations

   We'd need our own migration service or custom postgres image, which is just One More Thing to maintain and we'd have to update our apps to wait until the migration service is complete, not just that Postgres is online

[xritter1]

@paulineribeyre

[paulineribeyre]

😄