[Freedombox-discuss] don't write code - user-friendly configuration

[Jonas Smedegaard]

On Wed, Sep 01, 2010 at 12:48:58AM +0200, intrigeri wrote:
>Hi,
>
>Jonas Smedegaard wrote (31 Aug 2010 09:55:54 GMT) :
>> Package *reconfiguration* needs the ability to query current status. 
>> In current debconf you can query the debconf _cache_ of earlier 
>> responses, but cannot query the current choice as written to disk, so 
>> a user interface cannot inform the sysadmin of the consequences of 
>> making a choice - i.e. there is no "keep current choice" option.
>
>Config::Model and Config::Model::Backend::Augeas (Debian packages: 
>libconfig-model-perl and libconfig-model-backend-augeas-perl) might 
>help implementing such functionality in debconf or enabling Ægir to act 
>as a sysadmin without needing to fully take over conffiles (if it 
>actually does, which I have not checked).

Ah, yes, I simply forgot to praise these in my former (embarrassingly 
long) post.

I don't see them as debconf enhancements, though, but complements:

Debconf deals with package configurability, not what to do with the 
answers to questions asked.

Config::Model deals with configfile settings - it can be seen as a 
powerful replacement for dpkg-internal "conffile" mechanism and ucf, 
offering more reliable semantic 3-way merging (as opposed to 
line-based).

Config::Model::Backend::Augeas links (as I understand it) the semantic 
merging of Config::Model with UIs of Augeas - so may be an alternative 
to debconf.

Perhaps a debconf "lense" for Augeas could be implemented, to link it 
all together, but I am uncertain if that would simplify more than it 
complicates...

Above is technical details relevant for package maintainers to 
strengthen reliability of the configurability they offer through the 
packaging interface.

It may also be relevant for sysadmins wanting to grow a reliable 
configfile handling on top of Debian, essentially overruling the 
configfile maintainance offered by Debian.  FAI, CFEngine and Puppet 
belong in this category too.


Main point of my prior post was that I strongly recommend FreedomBox to 
be a Debian thing, rather than an on-top-of-Debian thing. I.e. *not* act 
on configfiles from a sysadmin point of view but as part of Debian, 
obeying Debian Policy which mandates no automated interaction directly 
with the content of other packages.  We should not make same mistake as 
Debian Edu in relying on Debian only for a) initial install and b) 
maintainance of _binary_ packaging parts, but also for c) maintainance 
of configfiles.

It is a *much* slower process to convince a Debian package maintainer to 
implement reliable packaging configurability for our needs than to hack 
ourselves on top of an installed package, but all hacks we invent we 
must *maintain* too, which is too likely to bit-rot down the road.


Regards,

  - Jonas

-- 
  * Jonas Smedegaard - idealist & Internet-arkitekt
  * Tlf.: +45 40843136  Website: http://dr.jones.dk/

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