= How to Install QWG Templates =
[[TracNav]]

[[TOC(inline)]]

''Note : QWG templates are intended to work both with original CVS-based CDB and the new Subversion-based [wiki:Doc/SCDB SCDB]. But their integration has been tested mainly with SCDB and tools described here applies mainly to SCDB. Report any problem you could encounter with original CDB.''


== Initial Installation ==

For an initial installation of QWG templates, you first need to initialize you repository with a base configuration database. If you want to use [wiki:Doc/SCDB SCDB], follow instructions on how to [wiki:Download/SCDB#SCDBInitialization configure] your Quattor server with SCDB, in particular [https://trac.lal.in2p3.fr/LCGQWG/wiki/Download/SCDB#SCDBInitialization SCDB initialization].

== Upgrading an existing repository ==

If you are using the recommended [wiki:Doc/TemplateCustom template layout] with separate areas for standard templates in your configuration database, upgrading should be no more than replacing the previous version of the templates.

We do our best to ensure that new versions are backward compatible. This means that if you made site customization using the [wiki:Doc described method] (pro_lcg2_config_site, pro_site_cluster_info...) and didn't modify standard templates, no changes should be required to use new version of the templates. When this is really required to introduce a new feature or bring more flexibility for configuring a service, it can happen that this full compatibility cannot be retained. This is normally stated in release announcement. You are always better to check...

Standard templates are made of 3 areas (see [wiki:Doc/TemplateCustom template layout]) :
 * OS templates : they are never modified, except for fixes. The only modifications apply to errata RPM list. These errata are not installed by default.
 * Middleware templates (if using them) : they bring both changes and fixes at each release. They are intended to be backward compatible : that means the resulting configuration should be the same if you don't change your local configuration. As part of QWG releases, they deliver gLite updates : `GLITE_UPDATE_VERSION` allows to control deployment of gLite updates as part of QWG templates update.
 * Standard templates : all modifications in this area are entirely backward compatible

There are 2 methods to upgrade QWG templates, according to the structure and constraints of your site :
 * In place upgrade : in this scenario, existing templates will be upgraded and the changes will be deployed on all clusters of your site. You can control the gLite updates you deploy on a per node basis.
 * Fresh installation of new middleware templates : this allows to control on a per cluster basis the deployement of new QWG templates. In this scenario, you are still doing an in-place upgrade of standard and OS templates.
 
=== In-place Upgrade ===

An in-place upgrade basically involves :
 * Checking out the QWG template release you need, in a separate area from your configuration database.
 * Synchronize your configuration database with your local copy of QWG templates.

''Note : you are advised to maintain an area where you have checked out QWG templates from [https://svn.lal.in2p3.fr/LCG/QWG/templates QWG repository] (never check out the whole `templates `branch` but only the version you need, [source:templates browse] through the repository to find it). This way updgrading to a new version is much more efficient : you can use `svn update` or `svn switch` to download only the changed bits.''

To integrate new/changed templates in your configuration database, you can use the tool documented at [wiki:Development/RepUpdate], originally developped to do the reverse synchronization (update QWG repository from a real configuration database). This tool can be used '''only''' with [wiki:Doc/SCDB SCDB], as it relies on [http://subversion.tigris.org Subversion] to do a non destructive update. As a benefit, it cannot damage your configuration database as every change made by this tool can be reverted with Subversion.

After importing all the changes with `directory-sync` (or manually), you need to commit them into your SCDB, after checking it compiles successfully and the changes in the profiles look appropriate (generally mainly some RPMS update). For this last check you can use `src/utils/profiles/compare_xml` script. After integrating the new templates, identify the changed templates, review the change if necessary and revert those not appropriate. You'll probably need to revert changes of all templates in directories `repository` (these templates are site specific but some of them are required to reside in standard directories for multiple version support).

''Note : when checking for changes brought by a new version, you can temporaly define `GLITE_UPDATE_VERSION` to your current version. This way you should have no changed RPMs.''


=== Fresh Installation of New Middleware Templates ===

In this scenario, you first have to download the new version of the templates, as in previous scenario. After, rather than sync'ing your templates with the release, you can copy the middleware templates provided by the release (e.g. `grid/glite-3.0.0`) in a new directory under `cfg/grid` in your CDB/SCDB and add them to the repository (use `svn add` for SCDB).

After you can select the deployment of the new release on a per cluster basis. For this, you have to edit `cluster.build.properties` of the cluster and update the include path, replacing references to previous release of middleware templates by reference to the new one you just added.