CircleCI rubyonrails 4.2, Yarn, React, Ruby 2.3, MySQL

config.yml

version: 2 # use CircleCI 2.0
jobs: # a collection of steps
  build: # runs not using Workflows must have a `build` job as entry point
    parallelism: 1 # run three instances of this job in parallel
    docker: # run the steps with Docker
      - image: circleci/ruby:2.3.4-jessie-node # ...with this image as the primary container; this is where all `steps` will run
        environment: # environment variables for primary container
          BUNDLE_JOBS: 3
          BUNDLE_RETRY: 3
          BUNDLE_PATH: vendor/bundle
          RAILS_ENV: test
      - image: circleci/mysql:5.7.28 # database image
        environment: # environment variables for database
          MYSQL_ALLOW_EMPTY_PASSWORD: 'yes'
    steps: # a collection of executable commands
      - checkout # special step to check out source code to working directory


      # - run:
      #     name: Dependencies
      #     command: |
      #       sudo apt-get update && \
      #       DEBIAN_FRONTEND=noninteractive apt-get install -y \
      #       build-essential mysql-client nodejs yarn && \
      #       apt-get clean && \
      #       rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*


      # Which version of bundler?
      - run:
          name: Which bundler?
          command: bundle -v

      # Restore bundle cache
      # Read about caching dependencies: https://circleci.com/docs/2.0/caching/
      - restore_cache:
          keys:
            - rails-demo-bundle-v2-{{ checksum "Gemfile.lock" }}
            - rails-demo-bundle-v2-

      - run: # Install Ruby dependencies
          name: Bundle Install
          command: bundle check --path vendor/bundle || bundle install --deployment

      # Store bundle cache for Ruby dependencies
      - save_cache:
          key: rails-demo-bundle-v2-{{ checksum "Gemfile.lock" }}
          paths:
            - vendor/bundle

      # Only necessary if app uses webpacker or yarn in some other way
      - restore_cache:
          keys:
            - rails-demo-yarn-{{ checksum "yarn.lock" }}
            - rails-demo-yarn-

      - run:
          name: Yarn Install
          command: yarn install --cache-folder ~/.cache/yarn

      # Store yarn / webpacker cache
      - save_cache:
          key: rails-demo-yarn-{{ checksum "yarn.lock" }}
          paths:
            - ~/.cache/yarn

      - run:
          name: Wait for DB
          command: |
            for i in `seq 1 10`;
            do
              nc -z 127.0.0.1 3306 && echo Success && exit 0
              echo -n .
              sleep 1
            done
            echo Failed waiting for MySQL && exit 1

      - run:
          name: Database setup
          command: bundle exec rake db:create db:migrate

      - run:
          name: Run rspec in parallel
          command: |
            bundle exec rspec --profile 10 \
                              --format documentation \
                              --out test_results/rspec.xml \
                              --format progress \
                              $(circleci tests glob "spec/**/*_spec.rb" | circleci tests split --split-by=timings)

      # Save test results for timing analysis
      - store_test_results: # Upload test results for display in Test Summary: https://circleci.com/docs/2.0/collect-test-data/
          path: test_results
      # See https://circleci.com/docs/2.0/deployment-integrations/ for example deploy configs