[augeas-devel] Re: New example at creating a lens

[Raphaël Pinson]

Hi there,

As we are in this subject, Augeas support was implemented in rpm some
time ago, but I don't think we have anything similar in dpkg. I don't
think it is very Debian-like to implement Augeas support within dpkg
directly, but obviously Augeas could solve a problem we currently have
when packaging for Debian. The current situation is (Debian Policy
masters, please correct me if I'm wrong) :

Packages are not supposed to modify existing configuration files unless :
   - they provide this file, or
   - they use a program provided by the package providing the
configuration file in order to modify it (e.g. useradd).

This makes it complicated because very few programs ship a
program/script to modify their configuration files. With Augeas
spreading, maybe Debian Policy could slightly modified to read :

Packages are not supposed to modify existing configuration files unless :
   - they provide this file, or
   - they use a program provided by the package providing the
configuration file in order to modify it, or
   - they use an augeas lens provided by the package providing the
configuration file.


This means that lenses should be provided with the programs they're
meant for. For example, the ntp package would provide ntp.aug, while
the sudo package would provide sudoers.aug, etc. This would also solve
the issue of configuration files versions. Currently, the lenses
shipped with Augeas do not take in consideration the version of the
program, and the specific fields/values of the configuration files
linked to this version. Shipping the lenses with the programs would
allow the lenses to be versionned together with the programs.

This is not a great new idea of course, as I think that David always
intended to let the upstream devs of each program take care of the
lenses in the future, but I think that shipping them in each package
in Debian could be a first step towards this, as long as package
maintainers are willing to do it, and maintain them for the time
being.

I have not put debian-devel in the recipients of this email because I
would like the opinion of the people on this list first.



Raphaël




On Wed, Jul 15, 2009 at 12:04 PM, Free Ekanayaka<free at 64studio.com> wrote:
> Hi,
>
> |--==> On Tue, 14 Jul 2009 20:55:53 +0200, Dominique Dumont <domi.dumont at free.fr> said:
>
>  > Hello
>  > As part of my mentor activity for GSoC 2009, I had to create a lens for Debian
>  > control files.
>
> Great!
>
> Out of curiosity, is the control lens targeted to some specific use
> case you're facing? Or is it just something you think it will possibly
> be useful in the future?
>
> Ciao,
>
> Free
>
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