mozilla-devscripts makes packaging extensions for XUL based applications easy. It provides a bunch of scripts and the CDBS snippet /usr/share/mozilla-devscripts/xpi.mk, which can be included by debian/rules. You only have to build a .xpi file, everything else will be done by mozilla-devscripts. It will extract the xpi file, remove extra license files, install it and set the links.

debian/rules

simplified dh 7

You can use this simplified dh 7 rule if your source contains the extracted .xpi file. This requires mozilla-devscripts (>= 0.22~).

#!/usr/bin/make -f

%:
        dh $@ --with xul-ext --buildsystem=xul_ext

extended dh 7

The xul_ext build system does nothing else than the following rule file. This rule file required only mozilla-devscripts (>= 0.19~). You can use this snippet if your extension provides a build system (like ant or make) and you need to override the dh_auto_build rule.

#!/usr/bin/make -f

%:
        dh $@ --with xul-ext

override_dh_auto_build:
        # put here the commands used for building the xpi file, for example:
        xpi-pack . xul-ext-fubar.xpi

override_dh_auto_install:
        install-xpi xul-ext-fubar.xpi

override_dh_auto_clean:
        rm -f xul-ext-fubar.xpi

multiple xpi files

Installing multiple xpi file is supported too.

#!/usr/bin/make -f

%:
        dh $@ --with xul-ext

override_dh_auto_build:
        # put here the commands used for building the xpi files, for example:
        make

override_dh_auto_install:
        install-xpi -p xul-ext-bla bla.xpi
        install-xpi -p xul-ext-keks keks.xpi

override_dh_auto_clean:
        rm -f *.xpi

CDBS

CDBS is support by mozilla-devscripts.

building from source

You have to run one command if you build the xpi file from source. Some extensions will provide a makefile to create the xpi file and you have to run "make", some will use ant and you have to run "ant", some will provide a shell script and you have to run "sh build.sh". Your debian/rules file will look like this with CDBS:

#!/usr/bin/make -f

MOZ_XPI_BUILD_COMMAND = sh build.sh

include /usr/share/cdbs/1/rules/debhelper.mk
include /usr/share/mozilla-devscripts/xpi.mk

An example for this design is notify-extension.

using xpi file

You should use med-xpi-unpack to create the source file if you use the xpi file from upstream. Please do not drop the xpi file into your sources. Your debian/rules file will be very simple if you use med-xpi-unpack to create the source. mozilla-devscripts will pack the files for you. You do not have to set MOZ_XPI_BUILD_COMMAND.

#!/usr/bin/make -f

include /usr/share/cdbs/1/rules/debhelper.mk
include /usr/share/mozilla-devscripts/xpi.mk

An example for this design is flashgot.

debian/control

The debian/control file will normally look like:

Source: EXTENSIONNAME
Section: web
Priority: optional
Maintainer: Debian Mozilla Extension Maintainers <pkg-mozext-maintainers@lists.alioth.debian.org>
Uploaders: Your Fullname <your@email.tld>
Build-Depends: debhelper (>= 9), mozilla-devscripts (>= 0.34~)
Standards-Version: 3.9.4
Homepage: http://example-extension.com/
Vcs-Git: git://git.debian.org/pkg-mozext/EXTENSIONNAME.git
Vcs-Browser: http://git.debian.org/?p=pkg-mozext/EXTENSIONNAME.git;a=summary

Package: xul-ext-EXTENSIONNAME
Architecture: all
Depends: ${misc:Depends}, ${xpi:Depends}
Recommends: ${xpi:Recommends}
Breaks: ${xpi:Breaks}
Provides: ${xpi:Provides}
Enhances: ${xpi:Enhances}
Description: one line for short description
 Long descriptions can span
 multiple lines
 .
 and as above empty lines

We maintain the extensions in git in the pkg-mozext group.
EXTENSIONNAME is the name of the extension. EXTENSIONNAME should not contain mozilla, iceape, icedove, iceape, firefox, thunderbird, seamonkey in its name. Append -extension to the source package name if EXTENSIONNAME is too generic without these name (The source package name for firefoxnotify is notify-extension and the binary package name is xul-ext-notify).
You need at least version 0.34~ of mozilla-devscripts for all features mentioned here.

debian/watch

This is an example watch file for an extension that is available on https://addons.mozilla.org/:

version=3
ftp://ftp.mozilla.org/pub/mozilla.org/addons/9622/firefoxnotify-([\d\.]+)-.*\.xpi

9622 needs to be replaces with the correct addon number.
firefoxnotify needs to be replaces with the name of the extension.
([\d\.]+) needs to be replaces by ([^-]+) (or similar) if the version of the extension contains alphabetical characters.
You might want to add xpi-repack to your debian/watch file (more details in the man page of xpi-repack).

This is an alternative example for the watch file which is supposed to be more up-to-date and more able to work since it uses the public website:

version=3
https://addons.mozilla.org/en-US/thunderbird/addon/stationery/ .*/stationery-([\d\.]+)-tb\.xpi.* debian xpi-repack