Using Puppet to contextualize computing resources for ATLAS analysis on Google Compute Engine

With the advent of commercial as well as institutional and national clouds, new opportunities for on-demand computing resources for the HEP community become available. With the new cloud technologies come also new challenges, and one such is the contextualization of cloud resources with regard to requirements of the user and his experiment. In particular on Google's new cloud platform Google Compute Engine (GCE) upload of user's virtual machine images is not possible, which precludes application of ready to use technologies like CernVM and forces users to build and contextualize their own VM images from scratch. We investigate the use of Puppet to facilitate contextualization of cloud resources on GCE, with particular regard to ease of configuration, dynamic resource scaling, and high degree of scalability.