Set up alembic migration usage

[PFischbeck]

This is a WIP of setting up Alembic for migrations, as suggested in #551.

How this works: Any time you change the DB models, you need to run poetry run alembic revision --autogenerate -m "Describe changes here". Anytime init_db.py is called, all alembic migrations are run if the database is not up-to-date.
I had to change a few imports in order to allow for alembic to find all models and have no circular dependencies.

Some thoughts of what's left to do:

• Maybe check whether migrations are necessary, see this suggestion in the alembic docs
• Maybe the initial migration should only add all tables if they don't already exist, so that all devs on mealie-next don't need to delete their database.
• We could think about using data migrations for the current seeding in init_db.py. The question basically is: what should happen if the seed data changes? Who should benefit from these changes, and how can we achieve that?
• The step for adding migrations should be documented somewhere
• We might want to add a test that ensures all upgrades are actually applicable
• We might want to add a CI test that ensures the migrations result in the current schema, see this discussion.

I only just found #357, so I'm not sure if I have missed anything.

[hay-kot]

This is excellent! Thanks for putting this together.

Maybe check whether migrations are necessary, see this suggestion in the alembic docs

I agree. I think at least doing some basic logging of "Migration needed performing migration" / "Migration not needed" would be sufficient for now.

Maybe the initial migration should only add all tables if they don't already exist, so that all devs on mealie-next don't need to delete their database.

I think that's a common pattern for migrations, create if not exist, is fairly common.

We could think about using data migrations for the current seeding in init_db.py. The question basically is: what should happen if the seed data changes? Who should benefit from these changes, and how can we achieve that?

I say we leave it for now, and cross that bridge later. Getting the initial migrations working with the existing setup is probably a better initial scope. I think we may be able to address this in another user-interactive way on the Frontend.

The step for adding migrations should be documented somewhere
We might want to add a test that ensures all upgrades are actually applicable
We might want to add a CI test that ensures the migrations result in the current schema, see sqlalchemy/alembic#724.

Yes. Yes and Yes! ✅ I don't think this is all strictly needed as apart of this PR. You can get the initial framework setup and then we can build on-top of that in future iterations and track progress in #551

In Summary - I think to get this merged I'd like to see at least some stubs setup for tests that are just marked as skip for now. That way when you, I or someone else want's to get this up to speed we have a clear idea of what needs to get tested. - What else did you want to tackle as apart of this before it gets merged?

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The main issue with the other PR is that it was pretty big and touched a lot of pieces of code when we didn't have many tests and the originator didn't write any tests for the work they did. Additionally, I couldn't reproduce his success on my machine so I ended up pulling out some of the parts and adding them into the main branch at the time.

[PFischbeck]

I've udpated the PR, including test stubs, and I think the rest can be done in other PRs:

• Document how to use alembic (but where?)
• Implement tests

We should wait with merging until you have finished #980, because that PR changes the DB schema quite a lot. After #980 is merged, I will have to update the initial_tables revision via alembic autogenerate, plus re-adding the "only update if tables don't exist yet" part.

[hay-kot]

PR #980 has been merged and I'm done with database changes until we setup alembic, so we can semi-officially put out a v1 Beta release. Let me know if you need anything else from me to get this ready-to merge.

Can't thank you enough for getting this going, if you're ever in Alaska I owe you a few beers 👍

[PFischbeck]

I think this is ready to merge 😄

I'll tell you if I'm ever in Alaska, but I owe you a few beers for creating Mealie!