In response to receipt of a notification from a third service, a scaling policy specified by a customer of a computing resource service provider to be associated with the notification is obtained, with the scaling policy including a set of parameters that includes an identity of a resource of a second service of the computing resource service provider. As a result of processing the scaling policy in accordance with the set of parameters, a request is submitted to a second service to scale the resource, and output is provided that indicates whether the scaling request has been fulfilled.