Run database migrations after pulling changes

[HebaruSan]

Motivation

After #369 was merged, the alpha server was left in a semi-functional state because its alembic migration wasn't executed. This command fixed it (I used the migration id in place of head, but I want to document the best version of it):

cd /SpaceDock
bin/alembic upgrade head

This happens automatically when you run ./start-server.sh, via ./spacedock database migrate:

SpaceDock/start-server.sh

Line 34 in ebb54cb

spacedock database migrate &&

... which does this:

SpaceDock/spacedock

Lines 12 to 15 in ebb54cb

	def _get_alembic_config():
	if os.path.isfile('alembic.ini'):
	from alembic.config import Config
	return Config('alembic.ini')

SpaceDock/spacedock

Lines 75 to 79 in ebb54cb

	cfg = _get_alembic_config()
	if cfg is not None:
	from alembic import command
	site_logger.info('Migrating database...')
	command.upgrade(cfg, 'head')

Changes

Now after the web hook pulls changes from GitHub, and before it restarts the sever, it also tries to run the alembic migrations.

[HebaruSan]

Will that work?

[DasSkelett]

After all these years! Nice to see this finally happening. Not to say I would've done this years ago, but... I'd have done this years ago.

Will that work?

Hard to say, testing this code section is a bit hard. I did run a manual

alembic.command.downgrade(alembic.config.Config('alembic.ini'), '426e0b848d77')
alembic.command.upgrade(alembic.config.Config('alembic.ini'), 'head')

which worked just fine (except one unrelated issue, see below). I don't see why it wouldn't in the celery task.

Also while running this on a new table, I realized that the new primary key of mod_followers from #369 isn't called pk_mod_followers but mod_followers_pkey if generated from scratch instead of the migration. This made the downgrade fail.
Appending name='pk_mod_followers' to the PrimaryKeyConstraint declaration should fix that.

Not a huge bug, it's unlikely that someone downgrades newly created databases except for testing, but it's nice to have things consistent. Do you want to add this to this PR, since we're already in the area of db migrations?

[HebaruSan]

Good catch, fixed.

[DasSkelett]

Found some more bugs while testing #357 and related to #369, but put them in my own separate PR, since they touch more code now that doesn't have anything to do with this PR.

[DasSkelett]

We'll only find out whether it works once we try it out on alpha, so let's give it a go.

[DasSkelett]

As far as I can tell it worked perfectly after merging #374:

$ sudo -u www-data bin/alembic current
833ba1ee8c72 (head)