Gitlab CI installation error - Could not find JavaScript runtime

Question

I am trying to configure Gitlab CI for my Ruby on Rails project, but have encountered an error that I do not know how to fix.

The application runs on Ruby 2.3.1, Rails 5.0 and uses the postgreSQL database.

My current .gitlab.ci.yml file is as follows:

# https://hub.docker.com/r/library/ruby/tags/
image: "ruby:2.3.0"

# Pick zero or more services to be used on all builds.
# Only needed when using a docker container to run your tests in.
# Check out: http://docs.gitlab.com/ce/ci/docker/using_docker_images.html#what-is-service
services:
  - redis:latest
  - postgres:latest
  - node:latest

# This is a basic example for a gem or script which doesn't use
# services such as redis or postgres
before_script:
  - gem install bundler         # Bundler is not installed with the image
  - bundle install -j $(nproc)  # Install dependencies

rubocop:
  script:
  - rubocop

rspec:
  script:
  - rspec spec

rails:
  script:
  - rails db:migrate
  - rspec spec

Therefore, it should use NodeJS as runtime. However, I get the following error:

$ rails db:migrate
rails aborted!
Bundler::GemRequireError: There was an error while trying to load the gem 'uglifier'.
Gem Load Error is: Could not find a JavaScript runtime. See https://github.com/rails/execjs for a list of available runtimes.
Backtrace for gem load error is:
/usr/local/bundle/gems/execjs-2.7.0/lib/execjs/runtimes.rb:58:in `autodetect'
/usr/local/bundle/gems/execjs-2.7.0/lib/execjs.rb:5:in `<module:ExecJS>'
/usr/local/bundle/gems/execjs-2.7.0/lib/execjs.rb:4:in `<top (required)>'
/usr/local/bundle/gems/activesupport-5.0.0.rc2/lib/active_support/dependencies.rb:293:in `require'
/usr/local/bundle/gems/activesupport-5.0.0.rc2/lib/active_support/dependencies.rb:293:in `block in require'
/usr/local/bundle/gems/activesupport-5.0.0.rc2/lib/active_support/dependencies.rb:259:in `load_dependency'
/usr/local/bundle/gems/activesupport-5.0.0.rc2/lib/active_support/dependencies.rb:293:in `require'
/usr/local/bundle/gems/uglifier-3.0.0/lib/uglifier.rb:5:in `<top (required)>'

Answer 1

You need javascript runtime (nodejs), install them.

Ubuntu Users

sudo apt-get install nodejs

CentOS / RedHat Users

sudo yum install nodejs

nodejs, therubyracer gem. :

JavaScript V8 Ruby.

Gemfile

gem 'therubyracer', platforms: :ruby