[RFC] can we just extend openembedded to get Isar 2.0

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

Hi,

looking at Isar it basically is a bitbake recipe to extract a bunch
of .debs into a rootfs. It also has support for a few more things, like
(cross-)compiling your own packages, basic configuration etc. Things
like image creation with wic have been added as well.

But a lot of things are still missing. For true customization one would
need a way to smuggle files into the rootfs, patch files in there,
execute scripts in there. Ideally with collision protection and special
protection for config-files etc. Claudius already suggested building
custom .debs in Isar to solve that.

Another thing i already came across is Image conversion .raw
-> .qcow2/.vdi/.vmdk all that is missing in Isar. Same was true for the
wic support until recently.

People that are coming from Yocto and want to switch to Isar will never
get their recipes to work, because all the utils-classes are missing in
Isar and would need to be ported/pulled-in.

Isar needs sudo, and someone has to integrate libpseudo.

Isar still has several small issues with correct rebuilds after config
changes etc.

OE solved all those problems already, but what it can not do is
fetch .debs from a mirror and bundle them together with multistrap. OE
most likely contains a lot of other usefull stuff that we might need
eventually. But without a doubt it also contains tons of stuff that we
do not need and that might confuse users if the have to look into it.

Does it really make sense for us to reinvent all those OE-features in
Isar, or should we just got the other way around and put the Isar
features into OE?

At a first glance it looks like you have to teach OE to get debian
packages and create a rootfs from them. Tell it to not compile anything
at first. Probably much like the do_rootfs from Isar. We might get away
with a layer on top of OE and maybe a few patches to OE that can maybe
be mainlined. Or maybe the whole thing could become mainline OE some
day.

Has anyone considered or even tried that already? Going down that road
sounds like solving a lot of the open points in Isar at once, by
adding a few 100 LoC to OE. But i might be totally wrong here.
I guess everyone working on Isar needs a good technical answer to
why we seemingly start from scratch.

Henning