Migflow

Migration intelligence for Rails teams.

Migflow is a Rails engine that mounts at /migflow and gives your team a visual timeline, schema diffs, and audit warnings — so you can understand migration impact before it reaches production.

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What it does

• Timeline — browse every migration in order, with version, name, and a one-line summary.
• Detail view — inspect raw migration content, schema snapshot, and audit warnings side by side.
• Schema diff — focused and full diff hunks powered by schema.rb patches between versions.
• Compare mode — pick any two migration versions and see exactly what changed.
• Schema graph — interactive ERD with tables, columns, foreign keys, and diff highlights.
• CI report — generate a Markdown or JSON report of all migrations and gate your pipeline on risk score.

Requirements

• Ruby >= 3.2
• Rails 7.0 or newer
• A Rails app with migrations in db/migrate and a db/schema.rb

Compatibility

Tested in CI against every combination below:

	Rails 7.0	Rails 7.1	Rails 7.2	Rails 8.1
Ruby 3.2	✅	✅	✅	✅
Ruby 3.3	✅	✅	✅	✅
Ruby 3.4	✅	✅	✅	✅
Ruby 4.0	✅	✅	✅	✅

Installation

Add Migflow to your Gemfile:

gem "migflow"

bundle install

Mount the engine in your routes:

# config/routes.rb
mount Migflow::Engine, at: "/migflow"

Start your app and open http://localhost:3000/migflow.

Configuration

All options are set in an initializer:

# config/initializers/migflow.rb
Migflow.configure do |config|
  # ...
end

Options

Option	Default	Description
migrations_path	db/migrate	Path to the migrations directory
schema_path	db/schema.rb	Path to the schema file
enabled_rules	:all	Audit rules to run. Pass an array of rule name symbols to enable a subset, or :all to run every rule
expose_raw_content	true	Whether to include the migration source code in the API response. Set to false to hide it
parent_controller	"ActionController::Base"	Controller class Migflow inherits from. Set to your app's ApplicationController to inherit authentication helpers
authentication_hook	nil	A lambda run as a before_action on every Migflow request. Use it to enforce authentication
unauthenticated_redirect	nil	A lambda returning the path to redirect to when authentication fails. Required when authentication_hook is set, because host app route helpers must be accessed via main_app.<helper> inside a mounted engine

Authentication

Migflow has no authentication out of the box. To protect the dashboard, set parent_controller to inherit your app's auth helpers, provide an authentication_hook to enforce the check, and set unauthenticated_redirect to tell Migflow where to send unauthenticated requests.

Rails 8 built-in Authentication

Migflow.configure do |config|
  config.parent_controller        = "ApplicationController"
  config.authentication_hook      = -> { require_authentication }
  config.unauthenticated_redirect = -> { main_app.new_session_path }
end

Devise

Migflow.configure do |config|
  config.parent_controller        = "ApplicationController"
  config.authentication_hook      = -> { authenticate_admin! }
  config.unauthenticated_redirect = -> { main_app.new_admin_session_path }
end

API

The frontend talks to these JSON endpoints under /migflow/api:

Method	Path	Description
GET	/migrations	List all migrations for the timeline
GET	/migrations/:version	Migration detail — warnings and schema patch
GET	/diff?from=:version&to=:version	Schema diff between two versions

CI report

Run the analysis from the command line without starting a server:

# Markdown summary (default)
bundle exec rails migflow:report

# JSON output for downstream tooling
bundle exec rails migflow:report FORMAT=json

# Gate: exit 1 if any migration has risk level high or above
bundle exec rails migflow:report FAIL_ON=high

# Gate: exit 1 if any migration scores 40 or above
bundle exec rails migflow:report FAIL_ON=40

# Write to a file instead of stdout
bundle exec rails migflow:report FORMAT=json OUTPUT=migflow-report.json

FAIL_ON accepts a level name (low, medium, high) or any integer score. Level names map to their minimum boundary (high → 71, medium → 31, low → 1), so FAIL_ON=medium catches medium and high migrations.

GitHub Actions

- name: Migration analysis summary
  run: bundle exec rails migflow:report FORMAT=markdown >> $GITHUB_STEP_SUMMARY

- name: Gate on high risk
  run: bundle exec rails migflow:report FAIL_ON=high

A ready-made workflow that triggers on pull requests touching db/migrate/ is included at .github/workflows/ci-report.yml.

Development

Prerequisites: Ruby 3.3, Node 22.

git clone https://github.com/jv4lentim/migflow.git
cd migflow
bin/setup

bin/setup installs Ruby and frontend dependencies. After that:

# Run tests
bundle exec rake spec

# Run linter
bundle exec rubocop

# Build frontend assets
cd frontend && npm run build

# Frontend dev server with hot reload (http://localhost:5173)
cd frontend && npm run dev

After rebuilding frontend assets, restart your Rails server to pick up the changes.

Testing against a local Rails app:

# In your app's Gemfile:
gem "migflow", path: "../migflow"

Limitations

• Read-only. Migflow only reads db/migrate/ and db/schema.rb — it never runs migrations or writes to the database.
• schema.rb required. Projects using structure.sql are not supported yet.
• Regex-based DSL parsing. SnapshotBuilder replays migration DSL calls with a regex scanner. Highly dynamic migrations (metaprogramming, loops, execute with raw SQL) may produce incomplete snapshots.
• No authentication out of the box. See Authentication to protect the dashboard before deploying to a shared environment.
• Single-app only. There is no support for multi-database setups or comparing migrations across separate Rails apps.

Roadmap

Planned in rough priority order:

• structure.sql support
• Baseline / waiver system — suppress known warnings explicitly and traceably
• Cross-branch comparison — diff migrations between two git branches without switching

Have an idea? Open a feature request.

Contributing

Issues and pull requests are welcome. See CONTRIBUTING.md for the full guide.

Code of Conduct

This project follows the Contributor Covenant.

License

Migflow is released under the MIT License.