On Fri, Aug 23, 2019 at 01:56:09PM -0400, Stephen Gallagher wrote:
So, I see the following options for how to handle default streams in
RHEL 8
Option 1: We disallow assigning default streams at all within EPEL 8.
This will protect us against a future change where RHEL wants to set a
default. Additionally, it means that all EPEL modules are explicitly
opt-in and so we don't ever surprise anyone.
Option 2: We allow making EPEL streams the default stream if RHEL does
not currently provide a default stream. We set strict policy regarding
what a default stream may contain (such as "must not replace any
package provided by RHEL 8"). If RHEL later decides to set a default
for this stream, the RHEL release engineering must ensure that the
`data.version` value is higher than what EPEL 8 carries.
I'm somewhat more in favor of Option 1 here, mostly because it
minimizes the chance of conflicts and ensures the opt-in nature of
EPEL. But I'm willing to hear counter-arguments.
I don't like the Option 1. It makes adding modularized packages into a build
root impossible. Efectivelly forcing everbody to modularize everything or
nothing. That's exactly the deficiency the modularity has in Fedora and does
not have in RHEL. The Option 1 makes the modularity in EPEL terrible as in
Fedora.
Example: RHEL has two perl streams:
perl:5.24
perl:5.26 [d]
You can add a non-modular perl-Foo package into EPEL bacause EPEL magically
adds perl:5.26 into the build root.
If you add a perl-Foo module into EPEL, you won't be able to set a default
stream, hence you won't be able to have it in the build root and therefore you
won't be able to add a non-modular perl-Bar package that requires a perl-Foo
module component into EPEL.
The only solution would be either add perl-Bar as a module, or not add
perl-Foo as a module. If you go the second path (i.e. no modules), it means
you won't be able build none of the packages for the non-default streams (i.e.
perl:5.24).
That effectively pushes modules into the role of leaf-only dependencies.
That's quite awkward situation if you consider that RHEL delivers language
runtimes as modules. The proposed EPEL policy would devalute the non-default
runtimes.
-- Petr