How to deploy a Ruby on Rails application

This guide walks you through deploying a Ruby on Rails application on Kualo hosting, using Redmine as a worked example. If you have not yet enabled Ruby in cPanel, start with Enabling Ruby in cPanel before continuing.

What is Redmine?

Redmine is a flexible, open-source project management web application built with Ruby on Rails. It is cross-platform and supports multiple databases.

Setting up the application in Ruby Selector

1. Open Ruby Selector in cPanel and add your application base folder.
2. Choose your Ruby version and set the application root path - for example, /home/rubytest/myapps/redmine.
3. Click Setup.

The selector creates three folders inside your application root by default: tmp, public, and logs. Any files that need to be publicly accessible must go inside the public folder.

After setup, the selector displays the command you need to activate the Ruby virtual environment via SSH.

Downloading Redmine

Connect to your account via SSH, then run the following commands to download and unpack Redmine into your application root:

cd myapps
wget https://www.redmine.org/releases/redmine-3.4.5.tar.gz
tar xvfz redmine-3.4.5.tar.gz
mv redmine-3.4.5/* redmine
rm -f redmine-3.4.5.tar.gz

Redmine already includes a public folder, so moving its contents directly into your application root is correct.

Installing Redmine

Step 1 - Create a database

Create a MySQL database and assign a user to it inside cPanel. Make a note of the database name, username, and password.

Step 2 - Configure the database connection

1. Navigate to myapps/redmine/config/.
2. Copy database.yml.example to database.yml.
3. Edit database.yml, keeping only the production block and updating it with your database details:

production:
  adapter: mysql2
  database: user_redmine
  host: localhost
  username: user_redmine
  password: my_password

Step 3 - Activate Ruby and install Bundler

Bundler reads the Gemfile in your application root and installs all required gems. First, activate the Ruby virtual environment using the command shown by the Ruby Selector, then install Bundler:

source /home/rubytest/rubyvenv/myapps_redmine/2.4/bin/activate
gem install bundler

Step 4 - Install dependencies

From the application root directory (where Gemfile is located), run:

bundle install --without development test

The --without development test flag tells Bundler to skip gems that are only needed for development and testing environments.

Step 5 - Resolve missing gem errors

If you see an error such as LoadError: cannot load such file -- bigdecimal, a required gem is missing from the Gemfile. The most reliable fix is to add it explicitly rather than installing it outside Bundler.

1. Open Gemfile in your application root.
2. Add the missing gem, for example:

gem "bigdecimal"

3. Run bundle install again to install the new dependency.

Step 6 - Generate a secret token

This command generates a random key that Rails uses to sign and encrypt session cookies. Run it from the application root:

bundle exec rake generate_secret_token

Generating a new token will invalidate any existing sessions after the next restart.

Step 7 - Set up the database schema

Create the database tables by running:

RAILS_ENV=production bundle exec rake db:migrate

Step 8 - Load default data

Populate the database with Redmine's default configuration data:

RAILS_ENV=production bundle exec rake redmine:load_default_data

Viewing your application

Once all steps are complete, visit your domain name in a browser. You should see your Ruby on Rails application running.