Docker is an open-source project that automates the deployment of Linux applications inside software containers. Docker containers wrap up a piece of software in a complete filesystem that contains everything it needs to run: code, runtime, system tools, system libraries – anything you can install on a server. This guarantees that the software will always run in the same manner, regardless of the environment in which it is executing.
This material covers two ways of deploying ATLAS software in docker containers. Firstly, a light-weight docker image, containing a basic Scientific Linux OS, provides ATLAS software through mounted CVMFS volumes. Secondly, a complete release is installed in a docker image, which only depends on external CVMFS volumes for conditions and geometry. In the topic materials provided in this guide, detailed information is given to install Docker on a personal Mac and an Ubuntu machine. This represents the current strategy for using ATLAS offline and/or analysis software on more modern OS platforms than e.g. CentOS 7.