CircleCiで、mysqlのDBに接続してテストを通す。ruby on rails

ruby on railsのCircleCiで結構はまったのでメモ

データベースの接続設定

appli/config/database.yml

default: &default
  adapter: mysql2
  encoding: utf8
  pool: <%= ENV.fetch("RAILS_MAX_THREADS") { 5 } %>
  username: root
  password:
  host: localhost

test:
  <<: *default
  username: 'root'
  password: 'rootpass'
  port: 3306
  host: '127.0.0.1'
  database: ci_test

circleci/config.yml

# Ruby CircleCI 2.0 configuration file
#
# Check https://circleci.com/docs/2.0/language-ruby/ for more details
#
version: 2
jobs:
  build:
    docker:
      # specify the version you desire here 
      - image: circleci/ruby:2.6.5-node-browsers
        environment:
          BUNDLER_VERSION: 2.0.1
          RAILS_ENV: test
          DB_HOST: 127.0.0.1
          DB_USERNAME: 'root'
          DB_PASSWORD: 'rootpass'

      - image: circleci/mysql:5.7.22
        environment:
          MYSQL_DATABASE: 'ci_test'
          MYSQL_USER: 'root'
          MYSQL_ROOT_PASSWORD: 'rootpass'
      # Specify service dependencies here if necessary
      # CircleCI maintains a library of pre-built images
      # documented at https://circleci.com/docs/2.0/circleci-images/
      # - image: circleci/postgres:9.4

    working_directory: ~/repo

    steps:
      - checkout
      - run:
          name: yarn install
          command: yarn install
      - run:
          name: setup bundler
          command: |
            sudo gem update --system
            sudo gem uninstall bundler
            sudo rm /usr/local/bin/bundle
            sudo rm /usr/local/bin/bundler
            sudo gem install bundler
        # Download and cache dependencies
      - restore_cache:
          keys:
            - v1-dependencies-{{ checksum "Gemfile.lock" }}
            # fallback to using the latest cache if no exact match is found
            - v1-dependencies-

      - run:
          name: install dependencies
          command: |
            yarn install --check-files
            bundle install --jobs=4 --retry=3 --path vendor/bundle

      - save_cache:
          paths:
            - ./vendor/bundle
          key: v1-dependencies-{{ checksum "Gemfile.lock" }}

      # Database setup
      - run:
          name: bundle exec
          command: |
            dockerize -wait tcp://127.0.0.1:3306 -timeout 120s
            bundle exec rake db:create
            bundle exec rake db:schema:load

      # run tests!
      - run:
          name: run tests
          command: |
            mkdir /tmp/test-results
            TEST_FILES="$(circleci tests glob "spec/**/*_spec.rb" | \
              circleci tests split --split-by=timings)"

            sudo gem install bundler
            sudo gem install rspec
            sudo gem install rspec-core
            bundle exec rspec \
              --format progress \
              --format RspecJunitFormatter \
              --out /tmp/test-results/rspec.xml \
              --format progress \
              $TEST_FILES

      # collect reports
      - store_test_results:
          path: /tmp/test-results
      - store_artifacts:
          path: /tmp/test-results
          destination: test-results