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

[Henning Schild <henning.schild@siemens.com>]

Am Fri, 8 Sep 2017 11:31:23 +0300
schrieb Alexander Smirnov <asmirnov@ilbers.de>:

> On 09/08/2017 11:15 AM, Henning Schild wrote:
> > Am Mon, 4 Sep 2017 18:36:23 +0300
> > schrieb 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:  
> > 
> > Well it is a capital "DEBIAN" folder that contains the package
> > metadata and no build instructions like 'debian'.
> >   
> >> 1. Why we need another do_deb_package, while do_build from dpkg
> >> class does the same?  
> > 
> > do_build does not do the same. It eventually calls
> > 'dpkg-buildpackage' which does "configure; make; make install; make
> > deb"
> > 
> > Using the same language this step is just "make deb" and it uses the
> > debian tool 'dpkg-deb'.
> > 
> > Custom steps for "configure; make;" could be added in the future.
> > "make install" is do_populate_package.  
> 
> Ok, I see now. But why it's done by host dpkg-deb tool? This should
> be done inside buildchroot to keep version compatibility. If you use
> host stretch and build for wheezy, there will be big gap in versions.

Thanks for pointing that out. That is a mistake just like the ARCH
thing Claudius pointed out. I will look into that.
I kindly ask you to review the patch again and provide such feedback
inline.

Henning

> >   
> >> 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.  
> > 
> > That would be adding support for 'debian'-izing a source package.
> > 
> > This patch is more about packaging binaries and creating
> > meta-packages. 
> 
> Ok.
>