The NorduGrid is a collaboration aiming at development, maintenance and support of the free Grid middleware, known as the Advanced Resource Connector (ARC). . For grid computing, a major challenge is to keep the working environments homogeneous between the sites. To help this situation, runtime environments have been developed. Those can be added to or removed from a site, and this Janitor service helps automating this process. . The Janitor is a recent development and the community to prepare catalogues of dynamically installable packages still needs to evolve.