That sounds like a good feature request. We will add it to our list.

Here’s how to rollback ALL migrations: https://gigalixir.readthedocs.io/en/latest/database.html#how-to-reset-the-database

Basically:

1. Drop into a remote console with gigalixir ps:remote_console
2. Run Ecto.Migrator.run(MyApp.Repo, Application.app_dir(:my_app, "priv/repo/migrations"), :down, [all: true])

I believe you can rollback a single item with:

Ecto.Migrator.run(MyApp.Repo, Application.app_dir(:my_app, "priv/repo/migrations"), :down, [step: 1])

Be sure to use your app name from mix.exs instead of MyApp and your app atom instead of :my_app.

It appears there is now a #down for Ecto.Migrator that might be useful.

More info here: Ecto.Migrator — Ecto SQL v3.8.3

Not a gigalixir user but it looks like ps:migrate is just a helper, maybe you could use the strategy used to deploy (and rollback) migrations in releases.

https://hexdocs.pm/ecto_sql/Ecto.Migrator.html#module-example-running-migrations-in-a-release

I would probably create a new migration that basically undo the previous one.