Module: Gitlab::Database::Migrations::ReestablishedConnectionStack

Included in:
Gitlab::Database::MigrationHelpers
Defined in:
lib/gitlab/database/migrations/reestablished_connection_stack.rb

Instance Method Summary collapse

Instance Method Details

#with_restored_connection_stack(&block) ⇒ Object

This is workaround for ‘db:migrate` that switches `ActiveRecord::Base.connection` depending on execution. This is subject to be removed once proper fix is implemented: gitlab.com/gitlab-org/gitlab/-/issues/362341

In some cases when we run application code we need to restore application connection stack:

  • ApplicationRecord (in fact ActiveRecord::Base): points to main

  • Ci::ApplicationRecord: points to ci

rubocop:disable Database/MultipleDatabases



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# File 'lib/gitlab/database/migrations/reestablished_connection_stack.rb', line 16

def with_restored_connection_stack(&block)
  original_handler = ActiveRecord::Base.connection_handler

  original_db_config = ActiveRecord::Base.connection_db_config
  if ActiveRecord::Base.configurations.primary?(original_db_config.name)
    return yield(ActiveRecord::Base.connection)
  end

  # If the `ActiveRecord::Base` connection is different than `:main`
  # re-establish and configure `SharedModel` context accordingly
  # to previously established `ActiveRecord::Base` to allow the application
  # code to use `ApplicationRecord` and `Ci::ApplicationRecord` usual way.
  # We swap a connection handler as migration context does hold an actual
  # connection which we cannot close.
  base_model = Gitlab::Database.database_base_models.fetch(original_db_config.name.to_sym)

  # copy connections over to new connection handler
  db_configs = original_handler.connection_pool_names.map do |connection_pool_name|
    [connection_pool_name.constantize, connection_pool_name.constantize.connection_db_config]
  end

  new_handler = ActiveRecord::ConnectionAdapters::ConnectionHandler.new
  ActiveRecord::Base.connection_handler = new_handler

  db_configs.each do |klass, db_config|
    new_handler.establish_connection(db_config, owner_name: klass)
  end

  # re-establish ActiveRecord::Base to main
  ActiveRecord::Base.establish_connection :main # rubocop:disable Database/EstablishConnection

  Gitlab::Database::SharedModel.using_connection(base_model.connection) do
    yield(base_model.connection)
  end
ensure
  ActiveRecord::Base.connection_handler = original_handler
  new_handler&.clear_all_connections!
end