docker-compose で　Mysql2::Error: No database selected

docker-compose で　railsアプリのコンテナとDBのコンテナを連携させようと試みています。
コンテナを起動して、ポートから接続を確認したところ、データベース関連のエラーを確認しました。

エラー文
Migrations are pending. To resolve this issue, run: rails db:migrate RAILS_ENV=development

migrationをしろとのことなので、migrationしようとしましたが、

DEPRECATION WARNING: Single arity template handlers are deprecated. Template handlers must
now accept two parameters, the view object and the source for the view object.
Change:
  >> Coffee::Rails::TemplateHandler.call(template)
To:
  >> Coffee::Rails::TemplateHandler.call(template, source)
 (called from <top (required)> at /myproject/rakefile:6)
rake aborted!
ActiveRecord::StatementInvalid: Mysql2::Error: No database selected
/usr/local/bundle/gems/mysql2-0.5.3/lib/mysql2/client.rb:131:in `_query'
/usr/local/bundle/gems/mysql2-0.5.3/lib/mysql2/client.rb:131:in `block in query'
/usr/local/bundle/gems/mysql2-0.5.3/lib/mysql2/client.rb:130:in `handle_interrupt'
/usr/local/bundle/gems/mysql2-0.5.3/lib/mysql2/client.rb:130:in `query'
/usr/local/bundle/gems/activerecord-6.0.2.1/lib/active_record/connection_adapters/abstract_mysql_adapter.rb:202:in `block (2 levels) in execute'
/usr/local/bundle/gems/activesupport-6.0.2.1/lib/active_support/dependencies/interlock.rb:48:in `block in permit_concurrent_loads'
/usr/local/bundle/gems/activesupport-6.0.2.1/lib/active_support/concurrency/share_lock.rb:187:in `yield_shares'
/usr/local/bundle/gems/activesupport-6.0.2.1/lib/active_support/dependencies/interlock.rb:47:in `permit_concurrent_loads'
/usr/local/bundle/gems/activerecord-6.0.2.1/lib/active_record/connection_adapters/abstract_mysql_adapter.rb:201:in `block in execute'
/usr/local/bundle/gems/activerecord-6.0.2.1/lib/active_record/connection_adapters/abstract_adapter.rb:718:in `block (2 levels) in log'
/usr/local/bundle/gems/activerecord-6.0.2.1/lib/active_record/connection_adapters/abstract_adapter.rb:717:in `block in log'
/usr/local/bundle/gems/activesupport-6.0.2.1/lib/active_support/notifications/instrumenter.rb:24:in `instrument'
/usr/local/bundle/gems/activerecord-6.0.2.1/lib/active_record/connection_adapters/abstract_adapter.rb:708:in `log'
/usr/local/bundle/gems/activerecord-6.0.2.1/lib/active_record/connection_adapters/abstract_mysql_adapter.rb:200:in `execute'
/usr/local/bundle/gems/activerecord-6.0.2.1/lib/active_record/connection_adapters/mysql/database_statements.rb:41:in `execute'
/usr/local/bundle/gems/activerecord-6.0.2.1/lib/active_record/connection_adapters/abstract/schema_statements.rb:315:in `create_table'
/usr/local/bundle/gems/activerecord-6.0.2.1/lib/active_record/connection_adapters/mysql/schema_statements.rb:81:in `create_table'
/usr/local/bundle/gems/activerecord-6.0.2.1/lib/active_record/schema_migration.rb:33:in `create_table'
/usr/local/bundle/gems/activerecord-6.0.2.1/lib/active_record/migration.rb:1206:in `initialize'
/usr/local/bundle/gems/activerecord-6.0.2.1/lib/active_record/migration.rb:1061:in `new'
/usr/local/bundle/gems/activerecord-6.0.2.1/lib/active_record/migration.rb:1061:in `up'
/usr/local/bundle/gems/activerecord-6.0.2.1/lib/active_record/migration.rb:1036:in `migrate'
/usr/local/bundle/gems/activerecord-6.0.2.1/lib/active_record/tasks/database_tasks.rb:238:in `migrate'
/usr/local/bundle/gems/activerecord-6.0.2.1/lib/active_record/railties/databases.rake:86:in `block (3 levels) in <top (required)>'
/usr/local/bundle/gems/activerecord-6.0.2.1/lib/active_record/railties/databases.rake:84:in `each'
/usr/local/bundle/gems/activerecord-6.0.2.1/lib/active_record/railties/databases.rake:84:in `block (2 levels) in <top (required)>'
/usr/local/bundle/gems/rake-13.0.1/exe/rake:27:in `<top (required)>'

Mysql2::Error: No database selected　というエラーがでてしまい、migrationができません。

database.yml

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

development:
  <<: *default

docker-compose.yml

version: '3'
services:
  db:
    image: mysql:5.6
    environment:
      MYSQL_DATABASE: root
      MYSQL_ROOT_PASSWORD: password
    volumes:
      - mysql-data:/var/lib/mysql
    ports:
      - "4306:3306"

  app:
    tty: true
    stdin_open: true
    build: .
    command: bundle exec rails s -p 3000 -b '0.0.0.0'
    ports:
      - "0.0.0.0:3000:3000"
    volumes:
      - .:/myproject
      - bundle:/usr/local/bundle
    links:
      - db

volumes:
  mysql-data:
  bundle:

おそらくDB関連の記述で間違えているのだと思いますが、色々試行錯誤しましたが解決できません。
どなたか、解決方法が分かる方、いらっしゃいませんか？

行動規範の内容に同意します

回答1件

ベストアンサー

database.yml に development 環境の database 名が入っていないように思いました。
（datanase.yml が途中で切られていなければですが...）

Railsの公式ドキュメントからの引用ですが、以下のように環境ごとに database の指定が必要だと思います。

yml
1development:
2  adapter: mysql2
3  encoding: utf8
4  database: blog_development # ここです
5  pool: 5
6  username: root
7  password:
8  socket: /tmp/mysql.sock