Policy for packaging extensions for XUL based applications

This is a draft and up for discussion on pkg-mozext-maintainers@lists.alioth.debian.org:

Filesystem Placement and Linking

The unpacked extension directory should be symlinked into the applications directory of every XUL application that can use the extension. For example, the package for an extension "adblock-plus" (em-id {d10d0bf8-f5b5-c8b4-a8b2-2b9879e08c5d}) which works with Iceape (app-id {92650c4d-4b8e-4d2a-b7eb-24ecf4f6b63a}) and Iceweasel (app-id {ec8030f7-c20a-464f-9b0e-13a3a9e97384}) should drop links into both /usr/share/mozilla/extensions/{ec8030f7-c20a-464f-9b0e-13a3a9e97384}/{d10d0bf8-f5b5-c8b4-a8b2-2b9879e08c5d} and /usr/share/mozilla/extensions/{92650c4d-4b8e-4d2a-b7eb-24ecf4f6b63a}/{d10d0bf8-f5b5-c8b4-a8b2-2b9879e08c5d}, each pointing to the unpacked extension directory. The extension can be installed directly into the applications directory instead of symlinking it if the extension supports only one XUL application.

Package Naming

The binary package's name should be xul-ext-<ext> with <ext> being the extension's name. E.g. xul-ext-nostalgy for Icedove's nostalgy extension. The source package's name should be <ext> or <ext>-extension if the name is too generic. E.g. adblock-plus, nostalgy, notify-extension.

In order to ease finding extensions for a given application the packages should

Provides: <xul-based-app1>-<extension>, <xul-based-app2>-<extension>, ...

and

Enhances: <xul-based-app1>, <xul-based-app2>, ...

where xul-based-app1 and xul-based-app2 are e.g. iceweasel and iceape.

Rationale:

Config Files

Note that many extensions contain default preferences files (e.g. defaults/preferences/fubar.js). Site administrators may want to override these preferences for their users, so they should be treated as conffiles. The simplest way to do this is to place an empty file under /etc/xul-ext (e.g. /etc/xul-ext/fubar.js), and create a symlink from defaults/preferences/000system.js in the unpacked xpi tree pointing to the file under /etc/xul-ext.

Implementation/Tools

It is recommended to use mozilla-devscripts. It will realize the policy for you.