Rack middleware to close Mongoid's connections to MongoDB. See https://github.com/mongoid/mongoid/issues/2369.

mongoid_close_connections.rb

require 'mongoid'

class MongoidCloseConnections
  def initialize(app)
    @app = app
  end
  
  def call(env)
    path = env['PATH_INFO'] || ''
    begin
      @app.call env
    ensure
      unless path.start_with?('/assets/')
        Mongoid.default_session.disconnect
      end
    end
  end
end