Le projet GRIF a choisi d’utiliser Quattor pour permettre une administration unifiée de la configuration de ses ressources distribuées sur plusieurs sites. C’est un composant clé de la mutualisation de l’administration entre les différentes composantes de GRIF.
Quattor is a software allowing to deploy and manage configuration of a huge number of systems, consistently and efficiently. It has been developped by EDG project, as part of WP4 effort (Fabric Administration). It is a critical key component in GRIF ability to share management tasks and load between all the GRIF sites.
Quattor aims to produce flexible but reproducible configurations. Instead of using imaging technology that are very efficient for initial installation but doesn’t allow to reconfigure the system after installation, Quattor is based on description of machine configuration using a language developped as part of Quattor : PAN. This language allow an efficient abstract description of the final machine configuration.
Configuration description is organized in templates. Templates can be used to describe basic services or configuration elements and are assembled to produce one machine specific configuration.
The configuration is produced by compiling templates. This compilation phase is a key feature of Quattor : it ensures consistency of the configuration and warranty that the configuration will be implemented with success.
This configuration is enforced on each node by a Quattor client that receive notification of any configuration changes applying to the current node and takes the appropriate actions, based on the difference between current and new configuration, through the execution of components.
Each component (implemented as a Perl script) is an engine responsible of one part of the configuration (account creation, filesystem management, gridmap management…). This engine receives its currents input from the configuration produced from templates and needs site customization.
Configuration compiled from templates can also be used to configure Red Hat installer (Anaconda/Kickstart) for initial installation of a system through PXE.
With these features, Quattor is unique installation and configuration management tool that provide a consistent and flexible way to manage machine configuration and apply configuration changes at any time, not just during installation.
Quattor is particularly powerful at managing a huge number (100 or 1000+ machines) sharing some common configuration. For example in the Grid context where you manage a large number of worker nodes all having the same configuration, you can change configuration on a worker node (e.g. add an AFS client) by just adding a few lines in a template and recompiling configuration. This will be deployed in a few minutes on all the worker nodes.
GRIF is a major contributor to Quattor developpement, particularly in 2 areas :
PAN compiler maintenance and improvement
Standard templates maintenance for operating system deployment (Scientific Linux or Red Hat Linux)
Templates maintenance include an important work done to allow a flexible template organization scheme. It has been driven by GRIF choice of Quattor to manage all the GRIF sites in a consistent way but preserving ability for each site to implement some specifities. Current Quattor templates organization is based on 3 set of templates :
Standard templates : 95% of the templates, can be used unmodified by every site
Site templates : site specific templates or site customization of standard templates.
Cluster templates : cluster specific templates or cluster customization of standard templates. A cluster is an arbitrary grouping of systems sharing some configuration.