Using containers with ATLAS offline software

This paper describes the deployment of ATLAS offline software in containers for software development. For this we are using Docker, which is a lightweight virtualization technology that encapsulates a piece of software inside a complete file system snapshot. The deployment of offline releases via containers removes the strict requirement of compatibility between the runtime environment needed for job execution and the configuration of worker nodes at computing sites. If these two are decoupled from each other, sites can upgrade their nodes whenever and however they see fit. In this work, ATLAS software is distributed in containers either via the CernVM File System (CVMFS) or by means of a full ATLAS offline release installation. In software development, separating the build and runtime environment from the development environment allows users to take advantage of many modern code development tools that may not be available in production runtime setups like SLC6. It also frees developers from depending on resources like lxplus at CERN, allowing the use of an average laptop for ATLAS code development. We include in this document a basic comparison in performance of the two deployment options in two popular host operating systems: Ubuntu and OS X.