RFC: Profile support

[Loïc Minier]

        Hey folks

 A very large number of people running pbuilder use it with multiple
 build environments.  Backports, sponsoring, company builds, Debian from
 Ubuntu or Ubuntu from Debian uploads, local repo, ...

 For instance, the ubuntu-dev-tools package ships two wrappers
 (pbuilder-dist and pbuilder-dist-simple) around pbuilder to manage
 multiple tarballs (one per $DIST).  I recently discovered another
 package of pbuilder scripts which would wrap pbuilder to offer one
 tarball per "project".  I use a relatively large set of wrappers
 myself.

 So I think pbuilder should support this better; it's easy to customize
 almost everything pbuilder does, but there is no standard way to save
 and re-use these customizations.

 I think we should consider a "profile" feature.  This would be a
 simple unix-name which would:
 - point to a /etc/pbuilder/$profile.pbuilderrc main config file
 - adapt pbuilder's pathnames for the tarball and result dirs, e.g.
   /var/cache/pbuilder/base-$profile.tgz and
   /var/cache/pbuilder/result-$profile or similar
 - store custom settings in the $profile.pbuilderrc, notably:
   * --distribution => DISRIBUTION=, --components etc.
   *  --mirror => MIRROR=, --othermirror etc.

 So on --create, the profile would be created with the settings used at
 this time, and subsequent --build, --update etc. with --profile foo
 would use the same settings automatically.  It's some kind of glorified
 --configfile.

 A couple of other related things I think would be worth improving are:
 * cross-arch support; this should simply work out of the box for the
   bi-arch cases (e.g. i386/amd64), but I'd also like to work 
 * support of multiple APT repos; currently this is supported via
   aptconfdir, but is not too nice to setup IMHO

 What do other maintainers think of the profile concept?

   Thanks,
-- 
Loïc Minier