Re: [PATCH 5/6] meta/dpkg: add dpkg-custom class

[Alexander Smirnov <asmirnov@ilbers.de>]

On 08/30/2017 10:03 PM, Henning Schild wrote:
> Issues:
> 1. full customizations of the images is hard to impossible to
> realize in a layer without touching Isar
> 1.1. there is no easy way to just copy a file into the image
> 1.2. configuration (passwords, groups, cfg-files changes) can not be
> done in a layer, there is no way too hook into multistrap or the
> configure-script
> 
> Change:
> Introduce a class that lets users create custom debian packages on the
> fly, without having to create a /debian directory and actually building.
> That allows you to pull in debian-dependencies, you could have a
> package that has no content and is just there to install what you need
> for a feature of your product.
> Using package hooks (preinst, postinst ..) you can configure pretty much
> all you want when installing the package.
> The package can contain actual payload as well, basically any files that
> come from "somewhere else". Say binary data like wallpapers, sound files
> or application binaries.
> 
> Impact:
> This patch addresses the metioned issue in a way that uses debian
> mechanism. All the customizations will enjoy features like
> - collission protection (multiple packages providing the same file)
> - config file protection
> - versioning and the ability to deploy your changes in an updateable way
> 
> This patch introduces a major new feature to Isar.
> 
> This class introduces a new class for building debian packages on the
> fly. They can basically contain anything from random sources, where
> building happens outside of Isar. It also allows to create meta-packages
> that contain nothing but pull in dependencies, once all our packets come
> in via multistrap that will come in handy.
> For rootfs configuration you would use post- and pre- scripts just like
> regular debian packages do.
> 

Good idea.

> Signed-off-by: Henning Schild <henning.schild@siemens.com>
> ---
>   meta/classes/dpkg-custom.bbclass | 57 ++++++++++++++++++++++++++++++++++++++++
>   1 file changed, 57 insertions(+)
>   create mode 100644 meta/classes/dpkg-custom.bbclass
> 
> diff --git a/meta/classes/dpkg-custom.bbclass b/meta/classes/dpkg-custom.bbclass
> new file mode 100644
> index 0000000..e4e743f
> --- /dev/null
> +++ b/meta/classes/dpkg-custom.bbclass
> @@ -0,0 +1,57 @@
> +# This software is a part of ISAR.
> +# Copyright (C) 2017 Siemens AG
> +
> +inherit dpkg
> +
> +DEBIAN_DEPENDS ?= ""
> +MAINTAINER ?= "FIXME Unknown maintainer"
> +
> +D = "${WORKDIR}/image/"
> +
> +# Populate folder that will be picked up as package
> +# TODO this should be called 'do_install'
> +do_populate_package() {
> +	bbnote "Put your files for this package in ${D}"
> +}
> +
> +addtask populate_package after do_unpack before do_deb_package_prepare
> +
> +# so we can put hooks etc. in there already
> +do_populate_package[dirs] = "${D}/DEBIAN"
> +
> +do_deb_package_prepare() {
> +	cat<<-__EOF__ > ${D}/DEBIAN/control
> +		Package: ${PN}
> +		Architecture: `dpkg --print-architecture`
> +		Section: misc
> +		Priority: optional
> +		Maintainer: ${MAINTAINER}
> +		Depends: `echo ${DEBIAN_DEPENDS} | tr '[:blank:]' ','`
> +		Version: ${PV}+isar
> +		Description: ${DESCRIPTION}
> +	__EOF__
> +	for t in pre post
> +	do
> +		for a in inst rm
> +		do
> +			chmod -f +x ${D}/DEBIAN/${t}${a} || true
> +		done
> +	done
> +}
> +
> +addtask deb_package_prepare after do_populate_package before do_deb_package_conffiles
> +
> +do_deb_package_conffiles() {
> +	CONFFILES=${D}/DEBIAN/conffiles
> +	find ${D} -type f -path '*/etc/*' | sed -e 's|^${D}|/|' >> $CONFFILES
> +	test -s $CONFFILES || rm $CONFFILES
> +}
> +
> +addtask deb_package_conffiles after do_deb_package_prepare before do_deb_package
> +
> +do_deb_package() {
> +	sudo chown -R root:root ${D}/DEBIAN/
> +	sudo dpkg-deb --build ${D} ${WORKDIR}
> +}
> +
> +addtask deb_package after do_deb_package_conffiles before do_install
> 

If I got this correctly, the difference from dpkg-debian flow is that 
you generate 'debian' folder on the fly. So:

1. Why we need another do_deb_package, while do_build from dpkg class 
does the same?

2. Can we just add optional task to generic pipeline which generates 
debian folder? Or make it as a part of do_build: if [ ! -d ${D}/debian 
]; then blablabla.

-- 
With best regards,
Alexander Smirnov

ilbers GmbH
Baierbrunner Str. 28c
D-81379 Munich
+49 (89) 122 67 24-0
http://ilbers.de/
Commercial register Munich, HRB 214197
General manager: Baurzhan Ismagulov