Re: [gentoo-dev] Gentoo LTS or: proper backward compatibility?

[m1027]

sam:

> > On 2 Jan 2023, at 12:48, m1027 <m1027@××××××.net> wrote:
> >
> > Hi and happy new year.
> >
> > When we create apps on Gentoo they become easily incompatible for
> > older Gentoo systems in production where unattended remote world
> > updates are risky. This is due to new glibc, openssl-3 etc.

[...]

> I'd really suggest just using stable in production and a mix
> for developers so you can catch any problems beforehand.
>
> We try to be quite conservative about things like OpenSSL 3,
> glibc updates, etc.

Thanks, a misunderstanding then: I am talking about stable only.

Whilst Gentoo may be conservative and all of you do an excellent job
on keeping things smooth, incompatibilities of software being newly
created on up-to-date developer systems (and then tried to be
distributed to outdated production systems) may arise multiple times
per year; *any* of the following alone may trigger a incompatibility.

Just some random examples:

(1) Most prominent, glibc updates. It has its sophisticated function
versioning. You may or may not be hit. It is not depending on
glibc's version but the internal function versions which are updated
in a quite subtile way. (Function versioning is without doubt an
impressive feature.)

(2) libjpeg: In the past, libjpeg reached version 9 (like on Ubuntu
today) but later was versioned 62 or 6.2 AFAIK. If you have an old
Gentoo production system still on libjpeg-9, you have a hard time to
update and distribute a new version of your app, as this version of
libjpeg is not present in Gentoo anymore. (Don't get me wrong, there
have probably been good reasons for this downgrade.) BTW: This
little incompatibility is one of the reasons why it is hard to
compile a app on Ubuntu for Gentoo.

(3) An older one: libressl was removed. Well, we all remember the
debate whether to keep it or not.

(4) There is openssl-3 showing up on the horizon. I expect
incompatibilities when distributing newly built software.

(5) Portage EAPIs: If there is a new EAPI and you emerge --sync,
then you need to update portage. This however, might require
surprisingly many other updates. New python, setuptools and friends.

I am not complaining here. Hey, we are on rolling release. Some of
you may even know individual solutions to work around each of it.
However, we just may get into trouble when distributing newly
compiled apps (on new Gentoo systems) to older Gentoo systems. And
we don't know in advance. I am looking for the best way to avoid
that.

Thanks