PygtkDebconf

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⇤ ← Revision 10 as of 2005-04-27 02:30:03 →
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Comment: make rationale a bit clearer
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Size: 3182
Editor: intern146
Comment: some cleanups
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The goal is to have an installer on the Live CD with a pretty graphical user interface. PyGTK may allow rapid development of such a GUI. The goal is to have an installer on the Live CD with a pretty graphical user interface. PyGTK should allow rapid development of such a GUI.
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== Scope and Use Cases ==

== Implementation Plan ==
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== Scope and Use Cases == It does not seem possible for an independent program to manipulate the debconf database directly. However, you can run arbitrary programs under debconf, which can then communicate with debconf in the same way that package install scripts do.
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== Implementation Plan == For example, to set a number of debconf keys, a shell script like the following could be used:
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Debconf questions are defined by template files in {{{/var/lib/dpkg/info/*.templates}}} files. The template files include the following info:
 * a key for the question (usually composed of the package name plus a unique identifier)
 * the type of the question (note, boolean, string, text, select, multiselect, etc)
 * descriptions in various languages.

We can set debconf database values by running a script under debconf. Implemented in shell, the script might look something like this:
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And could be run through debconf like this: The script would then be invoked like this:
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The noninteractive flag ensures that no debconf dialogs will be displayed. By not poking around in the debconf internals, this approach should function properly with both C-DebConf and Perl-DebConf.
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From the look of it, the installer won't be able to spawn debconf and talk to it directly.

One possible way to run things is like so:		 With this particular model, the install process might run like this:

PygtkDebconf

Status

Introduction

The goal is to have an installer on the Live CD with a pretty graphical user interface. PyGTK should allow rapid development of such a GUI.

Rationale

Scope and Use Cases

Implementation Plan

The Debian packaging system uses DebConf to ask questions of the user during package install. 

Package install  <=============> confmodule <=======> debconf
     script        shell calls                stdio

The debconf system then chooses how to present the questions to the user:

  • via a GUI (GTK, Qt, etc)
  • text based (newt)
  • no question -- take answer from Debconf database

The frontends are not cleanly separated from debconf, and must be implemented in the same language as the core debconf implementation. There are two debconf implementations (C and Perl). The C implementation is more amenable to having frontend bindings to other languages implemented in the future, but for a number of reasons it is not yet ready for mainstream use by the distribution outside the installer (although this is a long-term goal among debconf implementors).

For this reason, it may be best to write a normal PyGTK application that, on completion, primes the debconf database with answers and then kicks off the install.

It does not seem possible for an independent program to manipulate the debconf database directly. However, you can run arbitrary programs under debconf, which can then communicate with debconf in the same way that package install scripts do.

For example, to set a number of debconf keys, a shell script like the following could be used: 

  • . /usr/share/debconf/confmodule

db_set $KEY1 $VALUE1
db_set $KEY2 $VALUE2
...

The script would then be invoked like this: 

  • $ debconf -fnoninteractive program.sh

The noninteractive flag ensures that no debconf dialogs will be displayed. By not poking around in the debconf internals, this approach should function properly with both C-DebConf and Perl-DebConf.

With this particular model, the install process might run like this:

  1. installer prompts the user for required data
  2. installer writes data to a file
  3. installer runs "debconf -fnoninteractive install-values.sh"

  4. install-values.sh reads the data file written by the installer, and calls db_set for each key.

  5. installer starts the package install phase.

Data Preservation and Migration

This is for installing new systems, so there is no data to preserve or migrate.

Packages Affected

User Interface Requirements

Outstanding Issues

UDU BOF Agenda

UDU Pre-Work

UbuntuDownUnder/BOFs/PygtkDebconf (last edited 2008-08-06 16:14:48 by localhost)