feat: add RollbackAll to roll back all migrations

[gnuletik]

No description provided.

[gnuletik]

@amacneil is there anything blocking this PR that I can do? Thanks!

[gregwebs]

I opened #438 which allows a syntax for specifying a range of migration. That would work well combined with a command like this. But not sure if we should have a new command or have a --all flag?

[amacneil]

I think dbmate rollback --all is a good suggestion.

I put more thoughts in this comment.

[dossy]

Just wondering, @gnuletik, what is the semantic difference between rollback --all and drop followed by create? And, if they are, in theory, both meant to leave the system in an identical state, wouldn't drop followed by create be preferred as it's certainly faster to execute than a rollback --all would be?

Is there an expectation that rollback --all should leave the system in a different state than a drop followed by a create? I suppose this is the case if some migrations lack a "migrate down". But, then the system in that state may not be able to migrate up without error, which is a problem.

[gnuletik]

@dossy I totally agree with you.

Rolling back all migrations should leave the database in the same state as a new database if all up/down migrations file are clean.

If you missed something in your down migration, then applying all up migrations will fail. This is the use case I'm trying to cover with this command.

Having a rollback --all command would allow easy testing (e.g. in CI) of the down and up migrations.

[dossy]

Having a rollback --all command would allow easy testing (e.g. in CI) of the down and up migrations.

😲 🤯

Okay, that's a super clever use case for rollback --all!

You do a migrate, then a rollback --all, followed by another migrate and if that throws an error the second time around, you know there's an issue with your migration scripts, somewhere.

Well, I'm sold :) on the idea! I'm sorry I never saw #292 and your previous explanation in this comment -- thanks for repeating it here.

We'll need to add the --all subcommand option to the rollback command, update the README, and add some tests, but otherwise this looks good so far.

[wryanzimmerman]

Testing all down-migrations in CI is exactly the use-case which lead me to this thread, I'd love to see this added!

I actually did try rollback --all before searching to see if it existed, so I definitely think it would be intuitive.

[wryanzimmerman]

In case it helps anyone here's my intermediate solution:

for i in db/migrations/*
do
  if test -f "$i"
  then
    dbmate down
  fi
done;

This runs as a step in my CI. And it did catch one error I made in one down-migration!