Rails5.1 で導入された環境変数の暗号化機能
2018-10-02 追記 Rails 5.2 以降では encrypted secrets は廃止された模様.代わりに credentials を使うようにとのこと. https://github.com/rails/rails/blob/v5.2.0/activesupport/CHANGELOG.md Add config/credentials.yml.enc to store production app secrets. Allows saving any authentication credentials for third party services directly in repo encrypted with config/master.key or ENV["RAILS_MASTER_KEY"]. This will eventually replace Rails.application.secrets and the encrypted secrets...