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

[Claudius Heine <claudius.heine.ext@siemens.com>]

Hi agani, was a bit to fast sending the mail before,

On 08/31/2017 10:38 AM, [ext] Claudius Heine wrote:
> Hi
> 
> On 08/30/2017 09:03 PM, [ext] 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.
>>
>> 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
> 
> Also not a big fan of this name. 'custom' is a bit too unspecific for 
> what it does. I get that your idea that those packages are *custom* 
> made, but at the same time, so are all the packages that are directly 
> created within isar.
> 
> I liked the old 'dpkg-bin' name more, but maybe even this is a bit to 
> unspecific. How about 'dpkg-plain'? That describes better that those 
> packages are very simple, created impromptu without much to it, IMO.
> 
> Cheers,
> Claudius
> 
>>
>> 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() {

OE has a slightly different naming scheme for these tasks. They would 
call them 'do_package_deb_prepare' or similar [1]. Might cause confusion 
if we have different naming schemes between those two projects.

>> +    cat<<-__EOF__ > ${D}/DEBIAN/control
>> +        Package: ${PN}
>> +        Architecture: `dpkg --print-architecture`

Are you sure that this works when cross building? Wouldn't dpkg print 
the architecture of the host system instead of the target system? I 
think this kind of information has to come from the machine variables.

Cheers,
Claudius

>> +        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
>>
> 

[1] 
http://git.openembedded.org/openembedded-core/tree/meta/classes/package_deb.bbclass#n43

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