[CentOS-devel] Balancing the needs around the CentOS platform

On Mon, 21 Dec 2020 at 14:31, Mark Mielke <mark.mielke at gmail.com> wrote:

> On Mon, Dec 21, 2020 at 7:59 AM Stephen John Smoogen <smooge at gmail.com>
> wrote:
> > On Sun, 20 Dec 2020 at 22:19, Mark Mielke <mark.mielke at gmail.com> wrote:
> >> > > CentOS point releases do *not* match as closely as possible the
> >> > > corresponding RHEL point release?
> >> > No, no one is saying that.  Matthew said that you can stay at a minor
> >> > release of RHEL and still get security updates.  CentOS does not
> offer that.
> >> This is not correct. Please stop saying it. CentOS is bug-for-bug
> >> compatible with RHEL for *active* releases.
> > We came up with the phrase "bug-for-bug" compatible during EL5 as a GOAL
> to aim for. CentOS was NEVER bug-for-bug compatible. We aimed for it like a
> target to get to but we also had to release the software eventually and
> don't have the extensive testing mechanisms to prove 'bug-for-bug'
> compatibility. Sometimes CentOS shipped packages which did not have a
> particular bug because we could not exactly duplicate the build environment
> and other times we added new bugs because our build environment is not
> exactly the same.
>
> This is a good point of clarification. But, to be clear in both
> directions, please let us know if you agree that these points are
> correct:
>
> 1. CentOS was intended to be "bug-for-bug" compatible with RHEL as a GOAL.
> 2. This was especially difficult when Red Hat was not contributing to
> the project, as it involved a lot of guesswork and trial and error.
> 3. This became easier when Red Hat began contributing, including
> staging the source for build, and providing the build engines.
>

The methods for building the source to solution changed from dropping
.src.rpm to git pushes in EL7 time frame. The build engine changed from
running a highly modified version of plague? (reimzul) to koji. This did
not make things easier or worse overall. Some things became easier and some
things became harder.

What became easier was that Red Hat provided a lot of hardware and steady
paychecks for 5 or 6 people who had been doing the builds in their spare
time and out of pocket expenses.

4. It's still not perfect, however, in almost every way there is
> currently a 1:1 relationship between the exact .spec file and patch
> set being used to build CentOS releases, in parallel (or a short time
> later) to RHEL minor release.
>

A spec file is the tiniest part of making something match. Build order,
hardware, etc have a larger effect.



> 5. CentOS 8 Stream is a departure from the above. What is built in
> CentOS 8 Stream is *not* intended to be "bug-for-bug" compatible, but
>

CentOS-8 has not been bug-for-bug compatible in the first place. We would
still be working the initial release if we were trying that.  So please let
us rephrase this

5. CentOS 8 Stream is not intended to have the goal of being "bug-for-bug"
compatible. It is recognizing this is not possible and has not been
possible since probably EL5. At any given time it is not necessarily
aligned with RHEL X.Y or RHEL X.Y+1 but may be something in between or
beyond depending on when the release cycle is happening.

[That is the best over-simplification I can come up with this for.]

-- 
Stephen J Smoogen.
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