CircleCIでテストを実行する時に発生するデータベースを作成できないエラーの解決方法

実務未経験の初学者です。Docker, Rails, MySQLで開発して、CircleCIでテストを実行しようとすると、エラーが出てしまいます。
Ruby2.5.1
Rails5.2
MySQL5.7
docker-compose1.24.1
Docker19.03.4
エラーメッセージ

#!/bin/bash -eo pipefail
bundle exec rake db:create
Unknown MySQL server host 'db' (-2)
Couldn't create 'myapp_development' database. Please check your configuration.
rake aborted!
Mysql2::Error: Unknown MySQL server host 'db' (-2)
/home/circleci/repo/vendor/bundle/ruby/2.5.0/gems/mysql2-0.4.10/lib/mysql2/client.rb:89:in `connect'
/home/circleci/repo/vendor/bundle/ruby/2.5.0/gems/mysql2-0.4.10/lib/mysql2/client.rb:89:in `initialize'
/home/circleci/repo/vendor/bundle/ruby/2.5.0/gems/activerecord-5.2.4/lib/active_record/connection_adapters/mysql2_adapter.rb:22:in `new'
/home/circleci/repo/vendor/bundle/ruby/2.5.0/gems/activerecord-5.2.4/lib/active_record/connection_adapters/mysql2_adapter.rb:22:in `mysql2_connection'
/home/circleci/repo/vendor/bundle/ruby/2.5.0/gems/activerecord-5.2.4/lib/active_record/connection_adapters/abstract/connection_pool.rb:830:in `new_connection'
/home/circleci/repo/vendor/bundle/ruby/2.5.0/gems/activerecord-5.2.4/lib/active_record/connection_adapters/abstract/connection_pool.rb:874:in `checkout_new_connection'
/home/circleci/repo/vendor/bundle/ruby/2.5.0/gems/activerecord-5.2.4/lib/active_record/connection_adapters/abstract/connection_pool.rb:853:in `try_to_checkout_new_connection'
/home/circleci/repo/vendor/bundle/ruby/2.5.0/gems/activerecord-5.2.4/lib/active_record/connection_adapters/abstract/connection_pool.rb:814:in `acquire_connection'
/home/circleci/repo/vendor/bundle/ruby/2.5.0/gems/activerecord-5.2.4/lib/active_record/connection_adapters/abstract/connection_pool.rb:538:in `checkout'
/home/circleci/repo/vendor/bundle/ruby/2.5.0/gems/activerecord-5.2.4/lib/active_record/connection_adapters/abstract/connection_pool.rb:382:in `connection'
/home/circleci/repo/vendor/bundle/ruby/2.5.0/gems/activerecord-5.2.4/lib/active_record/connection_adapters/abstract/connection_pool.rb:1033:in `retrieve_connection'
/home/circleci/repo/vendor/bundle/ruby/2.5.0/gems/activerecord-5.2.4/lib/active_record/connection_handling.rb:118:in `retrieve_connection'
/home/circleci/repo/vendor/bundle/ruby/2.5.0/gems/activerecord-5.2.4/lib/active_record/connection_handling.rb:90:in `connection'
/home/circleci/repo/vendor/bundle/ruby/2.5.0/gems/activerecord-5.2.4/lib/active_record/tasks/mysql_database_tasks.rb:6:in `connection'
/home/circleci/repo/vendor/bundle/ruby/2.5.0/gems/activerecord-5.2.4/lib/active_record/tasks/mysql_database_tasks.rb:14:in `create'
/home/circleci/repo/vendor/bundle/ruby/2.5.0/gems/activerecord-5.2.4/lib/active_record/tasks/database_tasks.rb:119:in `create'
/home/circleci/repo/vendor/bundle/ruby/2.5.0/gems/activerecord-5.2.4/lib/active_record/tasks/database_tasks.rb:139:in `block in create_current'
/home/circleci/repo/vendor/bundle/ruby/2.5.0/gems/activerecord-5.2.4/lib/active_record/tasks/database_tasks.rb:316:in `block in each_current_configuration'
/home/circleci/repo/vendor/bundle/ruby/2.5.0/gems/activerecord-5.2.4/lib/active_record/tasks/database_tasks.rb:313:in `each'
/home/circleci/repo/vendor/bundle/ruby/2.5.0/gems/activerecord-5.2.4/lib/active_record/tasks/database_tasks.rb:313:in `each_current_configuration'
/home/circleci/repo/vendor/bundle/ruby/2.5.0/gems/activerecord-5.2.4/lib/active_record/tasks/database_tasks.rb:138:in `create_current'
/home/circleci/repo/vendor/bundle/ruby/2.5.0/gems/activerecord-5.2.4/lib/active_record/railties/databases.rake:29:in `block (2 levels) in <top (required)>'
/home/circleci/repo/vendor/bundle/ruby/2.5.0/gems/rake-13.0.1/exe/rake:27:in `<top (required)>'
/usr/local/bin/bundle:30:in `block in <main>'
/usr/local/bin/bundle:22:in `<main>'
Tasks: TOP => db:create
(See full trace by running task with --trace)
Exited with code 1

.circleci/config.yml

version: 2
jobs:
  build:
    docker:
      - image: circleci/ruby:2.5-node-browsers-legacy
        environment:
        RAILS_ENV: test
        DB_HOST: 127.0.0.1
      - image: mysql:5.7
        environment:
          MYSQL_USER: root
          MYSQL_ROOT_PASSWORD: ramadan
    working_directory: ~/repo
    steps:
      - checkout
      - restore_cache:
          keys:
            - v1-dependencies-{{ checksum "Gemfile.lock" }}
            - v1-dependencies-
      - run:
          name: install dependencies
          command: |
            bundle install --jobs=4 --retry=3 --path vendor/bundle
      - save_cache:
          paths:
            - ./vendor/bundle
          key: v1-dependencies-{{ checksum "Gemfile.lock" }}
      - run: bundle exec rake db:create
      - run: bundle exec rake db:schema:load
      - run:
          name: Update ChromeDriver Version
          command: |
            bundle exec rake webdrivers:chromedriver:update
      - run:
          name: Rspec
          command: |
            mkdir /tmp/test-results
            TEST_FILES="$(circleci tests glob "spec/**/*_spec.rb" | \
              circleci tests split --split-by=timings)"
            bundle exec rspec \
              --format progress \
              --out /tmp/test-results/rspec.xml \
              --format progress \
              $TEST_FILES
.
.
.

datebase.yml

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

development:
  <<: *default
  database: myapp_development
# Warning: The database defined as "test" will be erased and
# re-generated from your development database when you run "rake".
# Do not set this db to the same as development or production.
test:
  <<: *default
  database: myapp_test

docker-compose

version: '3'
services:
  rails:
    build: .
    ports:
      - "3000:3000"
    command: bundle exec rails s -p 3000 -b '0.0.0.0'
    volumes:
      - .:/myapp
    environment:
      - "SELENIUM_DRIVER_URL=http://selenium_chrome:4444/wd/hub"
    links:
      - db
  selenium_chrome:
    image: selenium/standalone-chrome-debug
    logging:
      driver: none
    depends_on:
      - db
    restart: unless-stopped 
  db:
    image: mysql:5.7
    environment:
      MYSQL_ROOT_PASSWORD: ramadan
      MYSQL_DATEBASE: root
    ports:
      - '3306:3306'
    volumes:
      - mysql_data:/var/lib/mysql
volumes:
  mysql_data:

Orlofsky

2019/12/03 09:30

エラーメッセージはキャプチャではなく、文字を https://teratail.com/help/question-tips#questionTips3-7 の [コード] に修正してください。

Aker

2019/12/03 09:37

了解です！

Orlofsky

2019/12/03 10:13

キャプチャは削っては？

Aker

2019/12/03 10:17

削りました

行動規範の内容に同意します

回答3件

自己解決

CircleCIのMySQLイメージをCircleCIが配布しているMySQLのイメージに変更したところうまく動きました。回答ありがとうございました。

circleci/.config.yml

 - image: mysql:5.7
      ↓
 - image: circleci/mysql:5.7

投稿2019/12/08 03:51

Aker

総合スコア15

docker-composeのdbイメージ側に、下記exposeの設定を追加したらどうなりますか?

docker
1expose:
2  - "3306"

※CircleCI上ではなく、ローカルでのdocker-compose実行はうまくできているのでしょうか？
もしそうならdocker-composeの問題ではないのかもしれないですが・・・

投稿2019/12/07 17:46

knr

総合スコア20

Aker

2019/12/08 03:40

回答ありがとうございます。docker-composeは実行できています。

行動規範の内容に同意します

docker-compose.ymlのrailsに

yaml
1links:
2  - db

を追加しないといけない気がします。この感じ：

yaml
1rails:
2  build: .
3  ports:
4    - "3000:3000"
5  command: bundle exec rails s -p 3000 -b '0.0.0.0'
6  volumes:
7    - .:/myapp
8  environment:
9    - "SELENIUM_DRIVER_URL=http://selenium_chrome:4444/wd/hub"
10  links:
11    - db