rails-db-schema-load-over-migrate

Detects GitHub Actions jobs that initialize an ephemeral Rails test database by replaying all migrations with rails db:migrate, and recommends rails db:schema:load instead.

Why This Matters

In CI, test databases are ephemeral—they are created fresh for each run and discarded afterward. Running db:migrate on every CI run executes every migration in sequence, which can take significantly longer than loading the current schema directly via db:schema:load (or db:structure:load for SQL schema dumps).

For large Rails applications with hundreds of migrations, the difference can be minutes per CI run.

Detection

The rule fires when a job meets all of the following:

1. Rails/Ruby job: uses ruby/setup-ruby, or runs bundle install, bundle exec, rails, rake, rspec, or bin/rails.
2. Ephemeral database: declares a services entry for PostgreSQL, MySQL, or MariaDB.
3. Test context: sets RAILS_ENV=test or RACK_ENV=test, or runs rails test, rake test, rspec, or bundle exec rspec.
4. Uses db:migrate: runs rails db:migrate, bin/rails db:migrate, bundle exec rails db:migrate, rake db:migrate, or bundle exec rake db:migrate.

Not Triggered When

• The job or workflow name suggests migration verification intent (e.g. contains migration, schema check, rollback, upgrade, compatibility).
• The command is a migration-variation such as db:migrate:redo, db:migrate:down, db:migrate:up, db:rollback, db:forward, or db:abort_if_pending_migrations.

Resolution

Replace the migration step:

- bundle exec rails db:migrate
+ bundle exec rails db:schema:load

If your project uses db/structure.sql instead of db/schema.rb:

- bundle exec rails db:migrate
+ bundle exec rails db:structure:load

Keep db:migrate only in jobs that intentionally test migration correctness, such as a “schema check” or “migration verification” workflow.

Severity

• High — when ephemeral DB service, test context, and db:migrate are all detected.