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docker-composeを使用してDockerfileでrake db：createを実行できません

Dockerfileとdocker-compose.ymltutorial と同様ですが、既存のアプリから始めます。

ぼくの docker-compose.ymlは次のようになります。

db:
  image: postgres
  ports:
    - "5432"
web:
  build: .
  command: bundle exec Rails s -p 3000 -b '0.0.0.0'
  volumes:
    - .:/myapp
  ports:
    - "3030:3030"
  links:
    - db

およびDockerfile：

FROM Ruby:2.1.4
RUN apt-get update -qq && apt-get install -y build-essential libpq-dev nodejs
RUN mkdir /myapp
WORKDIR /myapp
ADD Gemfile /myapp/Gemfile
RUN bundle install
ADD . /myapp
# RUN bundle exec rake db:create
# RUN bundle exec rake db:migrate
# RUN bundle exec rake db:seed

およびdatabase.yml

development:
  adapter: postgresql
  encoding: utf8
  database: myapp_development
  Host: db
  pool: 5
  username: postgres
  password:

ご覧のとおり、私はRUN bundle exec rake db:createエラーが発生したため：

could not translate Host name "db" to address: Name or service not known
/usr/local/bundle/gems/activerecord-3.2.21/lib/active_record/connection_adapters/postgresql_adapter.rb:1222:in `initialize'
/usr/local/bundle/gems/activerecord-3.2.21/lib/active_record/connection_adapters/postgresql_adapter.rb:1222:in `new'
/usr/local/bundle/gems/activerecord-3.2.21/lib/active_record/connection_adapters/postgresql_adapter.rb:1222:in `connect'
/usr/local/bundle/gems/activerecord-3.2.21/lib/active_record/connection_adapters/postgresql_adapter.rb:324:in `initialize'
/usr/local/bundle/gems/activerecord-3.2.21/lib/active_record/connection_adapters/postgresql_adapter.rb:28:in `new'
/usr/local/bundle/gems/activerecord-3.2.21/lib/active_record/connection_adapters/postgresql_adapter.rb:28:in `postgresql_connection'
/usr/local/bundle/gems/activerecord-3.2.21/lib/active_record/connection_adapters/abstract/connection_pool.rb:315:in `new_connection'
/usr/local/bundle/gems/activerecord-3.2.21/lib/active_record/connection_adapters/abstract/connection_pool.rb:325:in `checkout_new_connection'
/usr/local/bundle/gems/activerecord-3.2.21/lib/active_record/connection_adapters/abstract/connection_pool.rb:247:in `block (2 levels) in checkout'
/usr/local/bundle/gems/activerecord-3.2.21/lib/active_record/connection_adapters/abstract/connection_pool.rb:242:in `loop'
/usr/local/bundle/gems/activerecord-3.2.21/lib/active_record/connection_adapters/abstract/connection_pool.rb:242:in `block in checkout'
/usr/local/lib/Ruby/2.1.0/monitor.rb:211:in `mon_synchronize'
/usr/local/bundle/gems/activerecord-3.2.21/lib/active_record/connection_adapters/abstract/connection_pool.rb:239:in `checkout'
/usr/local/bundle/gems/activerecord-3.2.21/lib/active_record/connection_adapters/abstract/connection_pool.rb:102:in `block in connection'
/usr/local/lib/Ruby/2.1.0/monitor.rb:211:in `mon_synchronize'
/usr/local/bundle/gems/activerecord-3.2.21/lib/active_record/connection_adapters/abstract/connection_pool.rb:101:in `connection'
/usr/local/bundle/gems/activerecord-3.2.21/lib/active_record/connection_adapters/abstract/connection_pool.rb:410:in `retrieve_connection'
/usr/local/bundle/gems/activerecord-3.2.21/lib/active_record/connection_adapters/abstract/connection_specification.rb:171:in `retrieve_connection'
/usr/local/bundle/gems/activerecord-3.2.21/lib/active_record/connection_adapters/abstract/connection_specification.rb:145:in `connection'
/usr/local/bundle/gems/activerecord-3.2.21/lib/active_record/railties/databases.rake:144:in `rescue in create_database'
/usr/local/bundle/gems/activerecord-3.2.21/lib/active_record/railties/databases.rake:85:in `create_database'
/usr/local/bundle/gems/activerecord-3.2.21/lib/active_record/railties/databases.rake:62:in `block (3 levels) in <top (required)>'
/usr/local/bundle/gems/activerecord-3.2.21/lib/active_record/railties/databases.rake:62:in `each'
/usr/local/bundle/gems/activerecord-3.2.21/lib/active_record/railties/databases.rake:62:in `block (2 levels) in <top (required)>'
/usr/local/bundle/gems/rake-10.4.2/lib/rake/task.rb:240:in `call'
/usr/local/bundle/gems/rake-10.4.2/lib/rake/task.rb:240:in `block in execute'
/usr/local/bundle/gems/rake-10.4.2/lib/rake/task.rb:235:in `each'
/usr/local/bundle/gems/rake-10.4.2/lib/rake/task.rb:235:in `execute'
/usr/local/bundle/gems/rake-10.4.2/lib/rake/task.rb:179:in `block in invoke_with_call_chain'
/usr/local/lib/Ruby/2.1.0/monitor.rb:211:in `mon_synchronize'
/usr/local/bundle/gems/rake-10.4.2/lib/rake/task.rb:172:in `invoke_with_call_chain'
/usr/local/bundle/gems/rake-10.4.2/lib/rake/task.rb:165:in `invoke'
/usr/local/bundle/gems/rake-10.4.2/lib/rake/application.rb:150:in `invoke_task'
/usr/local/bundle/gems/rake-10.4.2/lib/rake/application.rb:106:in `block (2 levels) in top_level'
/usr/local/bundle/gems/rake-10.4.2/lib/rake/application.rb:106:in `each'
/usr/local/bundle/gems/rake-10.4.2/lib/rake/application.rb:106:in `block in top_level'
/usr/local/bundle/gems/rake-10.4.2/lib/rake/application.rb:115:in `run_with_threads'
/usr/local/bundle/gems/rake-10.4.2/lib/rake/application.rb:100:in `top_level'
/usr/local/bundle/gems/rake-10.4.2/lib/rake/application.rb:78:in `block in run'
/usr/local/bundle/gems/rake-10.4.2/lib/rake/application.rb:176:in `standard_exception_handling'
/usr/local/bundle/gems/rake-10.4.2/lib/rake/application.rb:75:in `run'
/usr/local/bundle/gems/rake-10.4.2/bin/rake:33:in `<top (required)>'
/usr/local/bundle/bin/rake:16:in `load'
/usr/local/bundle/bin/rake:16:in `<main>'
Couldn't create database for {"adapter"=>"postgresql", "encoding"=>"utf8", "database"=>"myapp_development", "Host"=>"db", "pool"=>5, "username"=>"postgres", "password"=>nil}

代わりにdocker-compose build次にdocker-compose run web rake db:createなど.

Dockerfileにdb-creation/migrationを含めることができないのはなぜですか。それは非常に明確になります。それを達成できますか？

ruby-on-railsdockerdocker-compose
20
Augustin Riedinger

webイメージがビルドされたとき（Dockerfileの指示に従って）、dbコンテナーへの接続がありません。

Webサーバーとデータベースの画像は独立していますとコンテナーは起動時にリンクされます（docker-compose.ymlファイルの定義に従います）。

イメージビルドは再現可能でなければならないという原則を破るため、イメージビルド中にコンテナーにリンクすることはできません。同様に、イメージのビルド中にホストマシンからボリュームをマウントすることもできません。

使用したdocker-compose run web rake db:createコマンドは、データベースを初期化する正しい方法です。

または、docker-composeを使用して通常どおりコンテナを起動し、docker execコマンドを使用してwebコンテナでrake db:createを実行することもできます。

22
Alexis N-o