Re: [meta-eid] multistrap support

[Baurzhan Ismagulov <ibr@radix50.net>]

On Wed, Feb 13, 2019 at 01:14:57PM +0000, kazuhiro3.hayashi@toshiba.co.jp wrote:
> I would like to know if isar still has some plans to use multistrap again
> (or similar existing tools if exists) to generate target images.
> 
> Multistrap for isar-image-base has been removed by the following commit:
> https://github.com/ilbers/isar/commit/19a314559178f7afd93ce3dafe8c8647ca6c8884
> and replaced by setup_root_file_system() in isar-bootstrap-helper.bbclass,
> which seems to use (pre-built?) isar-bootstrap-$ROOTFS_DISTRO-$ROOTFS_ARCH
> as the base tree instead of running the debootstrap process.
> 
> I guess that the main purposes of quitting multistrap is that
> there is no big update for a few years (though the last update is 2.2.10 on Nov. 2018)
> Are there any other reasons?
> (Some bugs difficult to be fixed, mismatches with isar specification, etc.)
> 
> The current isar-bootstrap based approach would work fine for isar system,
> but in that case, it might be difficult to share efforts for
> developing and maintaining the functionality with non isar users.
> I'm just interested in the future plan of isar.

Neil told us that he doesn't maintain multistrap anymore. We also encountered
issues (e.g., https://github.com/ilbers/isar/issues/16). For me personally,
Perl is an obstacle (I go through Perl tutorials every couple of years :) ). So
switching to debootstrap was easier at the time.

That is not to say that debootstrap is the tool we want to have. The focus of
debootstrap is to create Debian rootfss on Debian and non-Debian systems with
the least possible dependencies. Given that, it is developed in shell, which is
also not maintainable.

In the long run, we'll need more and more introspection into apt & Co. for more
advanced features. One way could be multistrap re-implementation in Python, as
suggested by Wookey. ELBE has good experiences with libapt. aptly also promises
some features we would like to use (though probably not multistrapping OOTB).

Bootstrapping hybrid repos is also a useful use case. It can be achieved by
making the "secondary" distribution upgradable from Debian, but if one has a
lot of customized packages, using multistrap would require less effort and be
less error-prone as well. In Isar, we try to stay away from massive
modifications, but there are projects ending up tuning significant parts of
Debian.

The specific tools don't have to be mutually exclusive; Python offers enough
polymorphism to include both as plugins (bitbake support has to be checked).
With quite diverse requirements and opinions we already have today, we'll need
pluggability, be it for multistrap or other features; the earlier we start
playing with it, the better. For me, it is the question of enough itch rather
than resources.

For your specific use case, I don't see a problem using multistrap for meta-eid
till we have a better alternative.

With kind regards,
Baurzhan.