Gitlab CI setup error - Could not find a JavaScript runtime

Question

I am trying to setup Gitlab CI for my Ruby on Rails project, but ran into an error that I don't know how to fix.

The application is running on Ruby 2.3.1, Rails 5.0 and is using a postgreSQL database.

My current .gitlab.ci.yml file looks like this:

# 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

So it's supposed to be using 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 to have a javascript runtime (e.g. nodejs). You can install it by using the following command:

For Ubuntu Users

sudo apt-get install nodejs

For CentOS / RedHat Users

sudo yum install nodejs

In case you can't install nodejs you can install and then use therubyracer gem.

Description from repository:

Embed the V8 JavaScript interpreter into Ruby.

Add this line to your Gemfile

gem 'therubyracer', platforms: :ruby

Answer 2

Gitlab-CI can be configured with the file .gitlab-ci.yml in this case:

before_script:
- apt-get update -qq && apt-get install -y -qq sqlite3 libsqlite3-dev nodejs

can be used to install nodejs on the setup stage (source).

A complete before_script with jekyll can look like the following code (for instance, this is required for jekyll-minifier):

image: ruby:latest

variables:
  JEKYLL_ENV: production
  LC_ALL: C.UTF-8

before_script:
  - apt-get update -qq && apt-get install -y -qq sqlite3 libsqlite3-dev nodejs
  - ruby -v
  - which ruby
  - gem install bundler
  - bundle install

test:
  stage: test
  script:
  - bundle exec jekyll build -d test
  artifacts:
    paths:
    - test
  except:
  - master

pages:
  stage: deploy
  script:
  - bundle exec jekyll build -d public
  artifacts:
    paths:
    - public
  only:
  - master