Integrate Webpack, React, React Router, Redux, and User Authentication with your Ruby on Rails application
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Repack gives you tools to integrate Webpack and React in to an existing Ruby on Rails application.

It will happily co-exist with sprockets but does not use it for production fingerprinting or asset serving. Repack is designed with the assumption that if you're using Webpack you treat Javascript as a first-class citizen. This means that you control the webpack config, package.json, and use npm to install Webpack & its plugins.

In development mode webpack-dev-server is used to serve webpacked entry points and offer hot module reloading. In production entry points are built in to public/client. Repack uses stats-webpack-plugin to translate entry points in to asset paths.

It was forked from the Marketplacer repo: ( and support for React / Babel / ES6 was added.

This gem has been tested against Rails 5 and Ruby 2.3.1 Earlier versions of Rails (>= 3.2) and Ruby (>= 1.9) may work, but we haven't tested them.

Using Repack

Install Options

  1. Basic Install: bundle exec rails g repack:install -> Webpack / React
  2. React / Redux Install: bundle exec rails g repack:redux_install -> Webpack / React / Redux Boilerplate
  3. React / Router Install: bundle exec rails g repack:router_install -> Webpack / React / React Router Boilerplate
  4. React / Router / Redux Install: bundle exec rails g repack:router_redux_install -> Webpack / React / Router / Redux Boilerplate
  5. GOD MODE: bundle exec rails g repack:god_install -> Webpack / React / React Router / Redux / Devise / Devise Token Auth / Bootstrap or Materialize Boilerplate.


  1. Add repack to your gemfile
  2. Run bundle install to install the gem
  3. See Install Options above and use 1 option
  4. Run npm run dev_server (or yarn run dev_server) to start webpack-dev-server
  5. Add the webpack entry point to your layout (see next section)
  6. Edit client/application.js and write some code

Adding the entry point to your Rails application

To add your webpacked javascript in to your app, add the following to the <body> section of any layout by default it has been added to application.html.erb:

<%= javascript_include_tag *webpack_asset_paths("application") %>

Take note of the splat (*): webpack_asset_paths returns an array, as one entry point can map to multiple paths, especially if hot reloading is enabled in Webpack.

Use with webpack-dev-server live reload

If you're using the webpack dev server's live reload feature (not the React hot reloader), you'll also need the following in your layouts/application template:

<script src="http://localhost:3808/webpack-dev-server.js"></script>

This has been added to layouts/application.html.erb by default.

Configuration Defaults

  • Webpack configuration lives in config/webpack.config.js
  • Webpack & Webpack Dev Server binaries are in node_modules/.bin/
  • Webpack Dev Server will run on port 3808 on localhost via HTTP
  • Webpack Dev Server is enabled in development & test, but not in production
  • Webpacked assets will be compiled to public/client
  • The manifest file is named manifest.json

View Generator

  1. Generate a controller
  2. Add at least an index route for the controller
  3. rails g repack:view name_of_view (should match controller name)


rails g controller Admin index
rails g repack:view admin

NOTE: The view generator will try to match its argument to a currently existing controller name, but if a controller cannot be found with that name, the generator will follow typical Rails convention and pluralize the view directory being created.

In an example where I have an AdminController & SessionsController:

rails g repack:view admin
(will find the AdminController and create views/admin/index.html.erb)

rails g repack:view sessions
(will find the SessionsController and create views/sessions/index.html.erb)

rails g repack:view user
(will not find a controller, will follow Rails controller naming convention and create views/users/index.html.erb)

Working with browser tests

In development, we make sure that the webpack-dev-server is running when browser tests are running.

Continuous Integration

In CI, we manually run webpack to compile the assets to public and set config.webpack.dev_server.enabled to false in our config/environments/test.rb:

  config.webpack.dev_server.enabled = !ENV['CI']

Production Deployment

If deploying to heroku, you will need to set your buildpacks before pushing. After adding the heroku git remote, run the below three commands:

  heroku buildpacks:clear
  heroku buildpacks:set heroku/nodejs
  heroku buildpacks:add heroku/ruby --index 2

This will set the Node.js buildpack to run first, followed by the Ruby buildpack. To confirm that your buildpacks are set correctly, run heroku buildpacks. You should see Node.js listed first and Ruby second.

Next you will need to set up a post build hook to bundle Webpack. Include the below scripts in package.json. For the Webpack deployment script, ensure that the route for your webpack.config.js file is correct.

  "scripts": {
    "webpack:deploy": "webpack --config=config/webpack.config.js -p",
    "heroku-postbuild": "npm run webpack:deploy"

Lastly, ensure that all Babel related modules are listed as dependencies and not dev dependencies in package.json. At this point, you should be able to push to Heroku.

An alternative to adding the post build hook to package.json is to add rake repack:compile to your deployment. It serves a similar purpose as Sprockets' assets:precompile task. If you're using Webpack and Sprockets (as we are at Marketplacer) you'll need to run both tasks - but it doesn't matter which order they're run in.

If you're using [chunkhash] in your build asset filenames (which you should be, if you want to cache them in production), you'll need to persist built assets between deployments. Consider in-flight requests at the time of deployment: they'll receive paths based on the old manifest.json, not the new one.

Example Apps


  • Add eslint to client
  • Integration tests
  • Port example apps to Repack


Pull requests & issues welcome. Advice & criticism regarding webpack config approach also welcome.

Please ensure that pull requests pass rspec. New functionality should be discussed in an issue first.


  • mipearson for his webpack-rails gem which inspired this implementation