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

[Free Ekanayaka]

Hi Raphaël,

|--==> On Wed, 15 Jul 2009 13:53:32 +0200, Raphaël Pinson <raphink at gmail.com> said:

  > As we are in this subject, Augeas support was implemented in rpm some
  > time ago.

Out of curiosity, how does rpm support it exactly? Pointers are
welcome (sorry I'm pretty new to the subject)

  > 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).

That's correct AFAICT.

  >    - they use an augeas lens provided by the package providing the
  > configuration file.

This sounds like a nice idea. The main problem I see is the work
overhead for the maintainer.

The whole point of the policy is to support smooth upgrades of
configuration files which haven't been touched directly by the system
administrators. So letting other packages modify a configuration file
via augeas would probably imply that in case of changes in the format
of that configuration file, the maintainer of the package providing
the file should ensure a smooth migration from the previous one to the
new, including possible modifications performed by other packages (and
that's why there very few packages providing scripts to modify their
configuration files).

However this a general problem, non strictly augeas-related, and
actually augeas would provide a good base to tackle it. So all in all
I'm for pushing the idea to debian-devel.

  > 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 another bad situation this idea would contribute to alleviate.

Ciao!

Free