マルチテナント用の gem である apartment を使っている Rails アプリを、
Heroku に push すると下記のエラーが発生した。
Preparing app for Rails asset pipeline
Running: rake assets:precompile
rake aborted!
Gem::LoadError: Specified 'sqlite3' for database adapter, but the gem is not loaded. Add `gem 'sqlite3'` to your Gemfile (and ensure its version is at the minimum required by ActiveRecord).
/tmp/build_4f21ff1d-af6a-46cb-ba2e-935e4be9cdd8/vendor/bundle/ruby/2.0.0/gems/activerecord-4.1.0/lib/active_record/connection_adapters/connection_specification.rb:190:in `rescue in spec'
/tmp/build_4f21ff1d-af6a-46cb-ba2e-935e4be9cdd8/vendor/bundle/ruby/2.0.0/gems/activerecord-4.1.0/lib/active_record/connection_adapters/connection_specification.rb:187:in `spec'
/tmp/build_4f21ff1d-af6a-46cb-ba2e-935e4be9cdd8/vendor/bundle/ruby/2.0.0/gems/activerecord-4.1.0/lib/active_record/connection_handling.rb:50:in `establish_connection'
/tmp/build_4f21ff1d-af6a-46cb-ba2e-935e4be9cdd8/vendor/bundle/ruby/2.0.0/gems/apartment-0.24.3/lib/apartment/adapters/abstract_adapter.rb:82:in `block in process_excluded_models'
/tmp/build_4f21ff1d-af6a-46cb-ba2e-935e4be9cdd8/vendor/bundle/ruby/2.0.0/gems/apartment-0.24.3/lib/apartment/adapters/abstract_adapter.rb:81:in `each'
/tmp/build_4f21ff1d-af6a-46cb-ba2e-935e4be9cdd8/vendor/bundle/ruby/2.0.0/gems/apartment-0.24.3/lib/apartment/adapters/abstract_adapter.rb:81:in `process_excluded_models'
/tmp/build_4f21ff1d-af6a-46cb-ba2e-935e4be9cdd8/vendor/bundle/ruby/2.0.0/gems/apartment-0.24.3/lib/apartment/database.rb:18:in `init'
/tmp/build_4f21ff1d-af6a-46cb-ba2e-935e4be9cdd8/vendor/bundle/ruby/2.0.0/gems/apartment-0.24.3/lib/apartment/railtie.rb:31:in `block in <class:Railtie>'
/tmp/build_4f21ff1d-af6a-46cb-ba2e-935e4be9cdd8/vendor/bundle/ruby/2.0.0/gems/activesupport-4.1.0/lib/active_support/callbacks.rb:438:in `instance_exec'
/tmp/build_4f21ff1d-af6a-46cb-ba2e-935e4be9cdd8/vendor/bundle/ruby/2.0.0/gems/activesupport-4.1.0/lib/active_support/callbacks.rb:438:in `block in make_lambda'
/tmp/build_4f21ff1d-af6a-46cb-ba2e-935e4be9cdd8/vendor/bundle/ruby/2.0.0/gems/activesupport-4.1.0/lib/active_support/callbacks.rb:184:in `call'
/tmp/build_4f21ff1d-af6a-46cb-ba2e-935e4be9cdd8/vendor/bundle/ruby/2.0.0/gems/activesupport-4.1.0/lib/active_support/callbacks.rb:184:in `block in simple'
/tmp/build_4f21ff1d-af6a-46cb-ba2e-935e4be9cdd8/vendor/bundle/ruby/2.0.0/gems/activesupport-4.1.0/lib/active_support/callbacks.rb:185:in `call'
/tmp/build_4f21ff1d-af6a-46cb-ba2e-935e4be9cdd8/vendor/bundle/ruby/2.0.0/gems/activesupport-4.1.0/lib/active_support/callbacks.rb:185:in `block in simple'
/tmp/build_4f21ff1d-af6a-46cb-ba2e-935e4be9cdd8/vendor/bundle/ruby/2.0.0/gems/activesupport-4.1.0/lib/active_support/callbacks.rb:86:in `call'
/tmp/build_4f21ff1d-af6a-46cb-ba2e-935e4be9cdd8/vendor/bundle/ruby/2.0.0/gems/activesupport-4.1.0/lib/active_support/callbacks.rb:86:in `run_callbacks'
/tmp/build_4f21ff1d-af6a-46cb-ba2e-935e4be9cdd8/vendor/bundle/ruby/2.0.0/gems/actionpack-4.1.0/lib/action_dispatch/middleware/reloader.rb:83:in `prepare!'
/tmp/build_4f21ff1d-af6a-46cb-ba2e-935e4be9cdd8/vendor/bundle/ruby/2.0.0/gems/actionpack-4.1.0/lib/action_dispatch/middleware/reloader.rb:55:in `prepare!'
/tmp/build_4f21ff1d-af6a-46cb-ba2e-935e4be9cdd8/vendor/bundle/ruby/2.0.0/gems/railties-4.1.0/lib/rails/application/finisher.rb:52:in `block in <module:Finisher>'
/tmp/build_4f21ff1d-af6a-46cb-ba2e-935e4be9cdd8/vendor/bundle/ruby/2.0.0/gems/railties-4.1.0/lib/rails/initializable.rb:30:in `instance_exec'
/tmp/build_4f21ff1d-af6a-46cb-ba2e-935e4be9cdd8/vendor/bundle/ruby/2.0.0/gems/railties-4.1.0/lib/rails/initializable.rb:30:in `run'
/tmp/build_4f21ff1d-af6a-46cb-ba2e-935e4be9cdd8/vendor/bundle/ruby/2.0.0/gems/railties-4.1.0/lib/rails/initializable.rb:55:in `block in run_initializers'
/tmp/build_4f21ff1d-af6a-46cb-ba2e-935e4be9cdd8/vendor/bundle/ruby/2.0.0/gems/railties-4.1.0/lib/rails/initializable.rb:54:in `run_initializers'
/tmp/build_4f21ff1d-af6a-46cb-ba2e-935e4be9cdd8/vendor/bundle/ruby/2.0.0/gems/railties-4.1.0/lib/rails/application.rb:288:in `initialize!'
/tmp/build_4f21ff1d-af6a-46cb-ba2e-935e4be9cdd8/config/environment.rb:5:in `<top (required)>'
/tmp/build_4f21ff1d-af6a-46cb-ba2e-935e4be9cdd8/vendor/bundle/ruby/2.0.0/gems/activesupport-4.1.0/lib/active_support/dependencies.rb:247:in `require'
/tmp/build_4f21ff1d-af6a-46cb-ba2e-935e4be9cdd8/vendor/bundle/ruby/2.0.0/gems/activesupport-4.1.0/lib/active_support/dependencies.rb:247:in `block in require'
/tmp/build_4f21ff1d-af6a-46cb-ba2e-935e4be9cdd8/vendor/bundle/ruby/2.0.0/gems/activesupport-4.1.0/lib/active_support/dependencies.rb:232:in `load_dependency'
/tmp/build_4f21ff1d-af6a-46cb-ba2e-935e4be9cdd8/vendor/bundle/ruby/2.0.0/gems/activesupport-4.1.0/lib/active_support/dependencies.rb:247:in `require'
/tmp/build_4f21ff1d-af6a-46cb-ba2e-935e4be9cdd8/vendor/bundle/ruby/2.0.0/gems/railties-4.1.0/lib/rails/application.rb:264:in `require_environment!'
/tmp/build_4f21ff1d-af6a-46cb-ba2e-935e4be9cdd8/vendor/bundle/ruby/2.0.0/gems/railties-4.1.0/lib/rails/application.rb:367:in `block in run_tasks_blocks'
/tmp/build_4f21ff1d-af6a-46cb-ba2e-935e4be9cdd8/vendor/bundle/ruby/2.0.0/gems/sprockets-rails-2.1.3/lib/sprockets/rails/task.rb:55:in `block (2 levels) in define'
Tasks: TOP => environment
(See full trace by running task with --trace)
!
! Precompiling assets failed.
!
! Push rejected, failed to compile Ruby app
Rails 初期化時に apartment の初期化を行っており、
database.yml に書かれている production 環境のアダプタを読み込もうとしてエラーが発生していた。
SQLite のアダプタを読み込もうとしたのが原因みたい。
Heroku に push したとき、
Heroku Postgres を使うように database.yml が自動で書き換わるんだけど、
Rails 初期化のタイミングではまだ書き換わっていなかったようだ。
database.yml で
production:
adapter: postgresql
host: HerokuPostgresホスト名
port: 5432
username: ユーザー名
password: パスワード
database: データベース名
という風に、SQLite ではなく PostgreSQL のアダプタを使うように書いておけば回避できた。