React on Rails Basic Tutorial

This tutorial guides you through setting up a new or existing Rails app with React on Rails, demonstrating Rails + React + Redux + Server Rendering. It is updated to 11.2.1.

After finishing this tutorial you will get an application that can do the following (live on Heroku):


You can find here:

By the time you read this, the latest may have changed. Be sure to check the versions here:

Note: some of the screen images below show the "npm" command. react_on_rails 6.6.0 and greater uses yarn.

Setting up the environment

Trying out React on Rails is super easy, so long as you have the basic prerequisites. This includes the basics for Rails 5.x and node version 6+. I recommend rvm and nvm to install Ruby and Node, and brew to install yarn. Rails can be installed as an ordinary gem.

nvm install node                # download and install latest stable Node
nvm alias default node          # make it default version
nvm list                        # check

brew install yarn               # you can use other installer if desired
rvm install 2.5.0               # download and install latest stable Ruby (update to exact version)
rvm use 2.5.0 --default         # use it and make it default
rvm list                        # check

gem install rails               # download and install latest stable Rails
gem install foreman             # download and install Foreman

Then we need to create a fresh Rails application with webpacker react support as following.

First be sure to run rails -v and check you are using Rails 5.1.3 or above. If you are using an older version of Rails, you'll need to install webpacker with react per the instructions here.

cd <directory where you want to create your new Rails app>

# any name you like for the rails app
rails new test-react-on-rails --webpack=react 

cd test-react-on-rails

Note: if you are installing React On Rails in an existing app or an app that uses Rails pre 5.1.3 (not for Rails > 5.2), you will need to run these two commands as well:

bundle exec rails webpacker:install
bundle exec rails webpacker:install:react

Add the React On Rails gem to your Gemfile:

gem 'react_on_rails', '11.2.1'         # prefer exact gem version to match npm version

Note: Latest released React On Rails version is considered stable. Please use the latest version to ensure you get all the security patches and the best support.

Run bundle and commit the git repository (or rails generate will not work properly)


# Here are git commands to make a new git repo and commit everything.
# Newer versions of Rails create the git repo by default.
git add -A
git commit -m "Initial commit"

Install React on Rails: rails generate react_on_rails:install or rails generate react_on_rails:install --redux. You need to first git commit your files before running the generator, or else it will generate an error.

rails generate react_on_rails:install
bundle && yarn

Then run server with static client side files:

foreman start -f

To run with the webpack-dev-server:

foreman start -f

Visit http://localhost:3000/hello_world and see your React On Rails app running! Note, foreman defaults to PORT 5000 unless you set the value of PORT in your environment or in the Procfile.

Using a pre-release of rails/webpacker

Until rails/webpacker v4 ships, or if you ever want to try out the master branch, you can modify the React on Rails tutorial instructions slightly. You can see the sequence of commits here. To summarize:

Don't run rails new with the --webpack=react option. Instead, add the webpacker gem to the Gemfile such that it points to master, like this if 11.2.1 is the version you want.

gem 'webpacker', github: "rails/webpacker"
gem 'react_on_rails', '11.2.1' # always use exact version

Then run these commands:

bundle exec rails webpacker:install
yarn add "rails/webpacker" # because the installer has a bug that puts in an invalid version in your package.json.
bundle exec rails webpacker:install:react
yarn add --dev webpack-dev-server
run rails generate react_on_rails:install && bundle && yarn

Custom IP & PORT setup (Cloud9 example)

In case you are running some custom setup with different IP or PORT you should also edit For example to be able to run on free Cloud9 IDE we are putting IP and PORT 8080. The default generated file uses -p 3000.

web: rails s -p 8080 -b

Then visit


It's super important to exclude certain directories from RubyMine or else it will slow to a crawl as it tries to parse all the npm files.

  • Generated files, per the settings in your config/webpacker.yml, which default to public/packs and public/packs-test
  • node_modules

Deploying to Heroku

Create Your Heroku App

Assuming you can login to and have logged into to your shell for heroku.

  1. Visit and create an app, say named my-name-react-on-rails:


Run this command that looks like this from your new heroku app

heroku git:remote -a my-name-react-on-rails

Set heroku to use multiple buildpacks:

heroku buildpacks:set heroku/ruby
heroku buildpacks:add --index 1 heroku/nodejs

Swap out sqlite for postgres by doing the following:

  1. Delete the line with sqlite and replace it with:
   gem 'pg'
  1. Run bundle


  1. Replace your database.yml file with this (assuming your app name is "ror").
default: &default
  adapter: postgresql
  host: localhost

  <<: *default
  database: ror_development

# Warning: The database defined as "test" will be erased and
# re-generated from your development database when you run "rake".
# Do not set this db to the same as development or production.
  <<: *default
  database: ror_test

  <<: *default
  database: ror_production

Then you need to setup postgres so you can run locally:

rake db:setup
rake db:migrate


I'd recommend adding this line to the top of your routes.rb. That way, your root page will go to the Hello World page for React On Rails.

root "hello_world#index"


Next, configure your app for Puma, per the instructions on Heroku.

Create /Procfile. This is what Heroku uses to start your app.


web: bundle exec puma -C config/puma.rb

Note, newer versions of Rails create this file automatically. However, the docs on Heroku have something a bit different, so please make it conform to those docs. As of 2018-10-13, the docs looked like this:


workers Integer(ENV['WEB_CONCURRENCY'] || 2)
threads_count = Integer(ENV['RAILS_MAX_THREADS'] || 5)
threads threads_count, threads_count


rackup      DefaultRackup
port        ENV['PORT']     || 3000
environment ENV['RACK_ENV'] || 'development'

on_worker_boot do
  # Worker specific setup for Rails 4.1+
  # See:

Then after all changes are done don't forget to commit them with git and finally you can push your app to Heroku!

git add -A
git commit -m "Changes for Heroku"
git push heroku master

Then run:

heroku open

and you will see your live app and you can share this URL with your friends. Congrats!

Turning on Server Rendering

You can turn on server rendering by simply changing the prerender option to true:

<%= react_component("HelloWorld", props: @hello_world_props, prerender: true) %>

Then push to Heroku:

git add -A
git commit -m "Enable server rendering"
git push heroku master

When you look at the source code for the page (right click, view source in Chrome), you can see the difference between non-server rendering, where your DIV containing your React looks like this:

<div id="HelloWorld-react-component-b7ae1dc6-396c-411d-886a-269633b3f604"></div>

versus with server rendering:

<div id="HelloWorld-react-component-d846ce53-3b82-4c4a-8f32-ffc347c8444a"><div data-reactroot=""><h3>Hello, <!-- -->Stranger<!-- -->!</h3><hr/><form><label for="name">Say hello to:</label><input type="text" id="name" value="Stranger"/></form></div></div>

For more details on server rendering, see:

ShakaCode recommends that you use /client for your client side app. This way a non-Rails, front-end developer can be at home just by opening up the /client directory.

  1. Move the directory:
mv app/javascript client
  1. Edit your /config/webpacker.yml file. Change the default/source_path:
  source_path: client

Using HMR with the rails/webpacker setup

Start the app using foreman start -f

When you change a JSX file and save, the browser will automatically refresh!

So you get some basics from HMR with no code changes. If you want to go further, take a look at these links:

React on Rails will automatically handle disabling server rendering if there is only one bundle file created by the Webpack development server by rails/webpacker.


Feedback is greatly appreciated! As are stars on github!

If you want personalized help, don't hesitate to get in touch with us at [email protected]. We offer React on Rails Pro and consulting so you can focus on your app and not on how to make Webpack plus Rails work optimally.

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