開発環境

AWSサーバー使用
自動デプロイツールcapistrano使用

状況

ローカル環境で、データベースを一度削除し、作り直して、'bundle exec cap production deploy'コマンドを実行した際に、以下のようなエラーが出た。

Caused by:
 DEBUG [7ec9cb7c] 	ArgumentError: Index name 'index_boards_on_user_id' on table 'boards' already exists
 DEBUG [7ec9cb7c] 	/var/www/forum-lastapp/shared/bundle/ruby/2.6.0/gems/activerecord-6.0.3.6/lib/active_record/connection_adapters/abstract/schema_statements.rb:1197:in `add_index_options'
/var/www/forum-lastapp/shared/bundle/ruby/2.6.0/gems/activerecord-6.0.3.6/lib/active_record/connection_adapters/mysql/schema_creation.rb:65:in `index_in_create'
/var/www/forum-lastapp/shared/bundle/ruby/2.6.0/gems/activerecord-6.0.3.6/lib/active_record/connection_adapters/abstract/schema_creation.rb:49:in `block in visit_TableDefinition'
/var/www/forum-lastapp/shared/bundle/ruby/2.6.0/gems/activerecord-6.0.3.6/lib/active_record/connection_adapters/abstract/schema_creation.rb:49:in `map'
/var/www/forum-lastapp/shared/bundle/ruby/2.6.0/gems/activerecord-6.0.3.6/lib/active_record/connection_adapters/abstract/schema_creation.rb:49:in `visit_TableDefinition'
/var/www/forum-lastapp/shared/bundle/ruby/2.6.0/gems/activerecord-6.0.3.6/lib/active_record/connection_adapters/abstract/schema_creation.rb:14:in `accept'
/var/www/forum-lastapp/shared/bundle/ruby/2.6.0/gems/activerecord-6.0.3.6/lib/active_record/connection_adapters/abstract/schema_statements.rb:315:in `create_table'
/var/www/forum-lastapp/shared/bundle/ruby/2.6.0/gems/activerecord-6.0.3.6/lib/active_record/connection_adapters/mysql/schema_statements.rb:81:in `create_table'
/var/www/forum-lastapp/shared/bundle/ruby/2.6.0/gems/activerecord-6.0.3.6/lib/active_record/migration.rb:890:in `block in method_missing'
/var/www/forum-lastapp/shared/bundle/ruby/2.6.0/gems/activerecord-6.0.3.6/lib/active_record/migration.rb:858:in `block in say_with_time'
/var/www/forum-lastapp/shared/bundle/ruby/2.6.0/gems/activerecord-6.0.3.6/lib/active_record/migration.rb:858:in `say_with_time'
以下省略

解決法

ローカルでデータベース関連の内容を修正した場合の対処が必要となる。

本番環境で以下二つのコマンドを実行する
% rails db:drop RAILS_ENV=production DISABLE_DATABASE_ENVIRONMENT_CHECK=1
% rails db:create RAILS_ENV=production

その後、一度プロセスをkillした上で「bundle exec cap production deploy」を実行すると、エラーは解決された。