Automated software packaging and installation for the ATLAS experiment

Authors: Michael Gardner (RHUL), Simon George (RHUL), Roger Jones (Lancaster), 
Christian Arnault (Orsay), Saul Youssef (Boston)

Keyword: ATLAS experiment; installation; packaging; deployment

   Managing the distribution and installation of large and complex 
   software suites such as the ATLAS offline software[1] gives rise  
   to  a variety of problems. To be able to deploy software on the Grid 
   it must have a completely automated installation procedure which
   addresses issues such compatability, updates and external software 
   required. Installations are needed to satisfy the different
   requirements of the production run, a developer (with his/her own
   code) and the possibility to rebuild from source.

   A solution to this problem has been developed in the context of
   ATLAS offline software.  ATLAS uses CMT[2] to configure and manage
   `packages', which are the basic units of the software. Crucially
   for this project, CMT allows the definition and imposition of
   conventations for package metadata. Pacman[3] is a package manager
   that facilitates transparent fetching, installation and management
   of software packages. These two pieces of widely used software
   provide much of the functionality required to meet the distribution
   and installation needs of ATLAS; the main work is to interface them
   and solve some problems of the ATLAS software itself. To this end,
   additional tools have been developed to extract files in common
   package formats (such as tar and rpm) and make the Pacman cache
   files. The cache files describe all the information needed to fetch
   and install a package, including its dependencies on other
   packages. These tools work closely with cmt to exploit the conventions
   for expresseing package metadata.

   External packages are handled by additional metadata written in
   interface packages, thus allowing them to be packaged in a similar way. The
   presence of basic system packages is tested before the download and
   installation commences.

[1] ATLAS offline software http://atlas.web.cern.ch/Atlas/GROUPS/SOFTWARE/OO/
[2] CMT http://www.cmtsite.org/
[3] Pacman http://physics.bu.edu/~youssef/pacman/