Rails 6 connection management to handle Amazon Aurora's failover

reconnect.rb

# frozen_string_literal: true

require 'active_record/connection_adapters/reconnect_on_error_management'

Rails.application.config.middleware.insert_before ActionDispatch::Executor, ActiveRecord::ConnectionAdapters::ReconnectOnErrorManagement unless Rails.env.test?

reconnect_on_error_management.rb

# frozen_string_literal: true

module ActiveRecord
  module ConnectionAdapters
    class ReconnectOnErrorManagement
      CONNECTION_ERROR = ['Lost connection', 'gone away', '--read-only'].freeze
      CONNECTION_ERROR_RE = /#{CONNECTION_ERROR.map { |w| Regexp.escape(w) }
.join('|')}/.freeze
      CONNECTION_ERROR_RE.freeze

      def initialize(app)
        @app = app
      end

      def call(env)
        testing = env.key?('rack.test')

        response = @app.call(env)
        response[2] = ::Rack::BodyProxy.new(response[2]) do
          ActiveRecord::Base.clear_active_connections! unless testing
        end

        response
      rescue Exception => e
        unless testing
          if should_clear_all_connections?(e)
            ActiveRecord::Base.clear_all_connections!
          else
            ActiveRecord::Base.clear_active_connections!
          end
        end
        raise
      end

      def should_clear_all_connections?(e)
        return CONNECTION_ERROR_RE === e.message if e.is_a?(ActiveRecord::StatementInvalid)

        false
      end
    end
  end
end