[CentOS] Understanding modularity

Tue Apr 28 06:07:47 UTC 2020
Simon Matter <simon.matter at invoca.ch>

> Am 27.04.20 um 17:31 schrieb Simon Matter via CentOS:
>>> On 4/27/20 8:27 AM, Simon Matter via CentOS wrote:
>>>> Hi,
>>>> I've read the Fedora modularity docs but am still missing the big
>>>> picture
>>>> somehow. Hope someone can clarify things for me.
>>>> What I'm most wondering: does modularity have any influence on the RPM
>>>> packages at all. I mean, is there anything inside a RPM package which
>>>> says
>>>> it belongs to a module or it has a special function in a module?
>>>> >From what I understand the RPMs are just completely normal packages
>>>> and
>>>> only YUM/DNF knows from some metadata that an RPM belongs to a module.
>>>> Is
>>>> that corrent?
>>> Well .. yes and no.
>>> Individual rpm packages have requirements for install .. so if a
>>> package
>>> is built against python38 , it will require python38 libraries.  The
>>> individual RPMs though do not have knowledge specifically about Modules
>>> though, just the metadata.
>> Okay, so the rpm has it's usual provides and requires, in this case a
>> requirement for python38.
>> Still, I don't really understand how it can work for a simple example I
>> have in mind. Let's say there is this new, shiny Apache httpd version
>> 3.0.0 which requires this new and incompatible zlib version 2.0.0.
>> How can this be built with modules? Dozen of RPMs depend on zlib version
>> 1.x.x, how is this situation handled with modules.
>> Sorry, I just don't really understand.
> IIRC: A module is just a set of RPM packages that can or must be
> installed together. Modules of the same "applications" can not be
> installed at the same time (postgresql 10 or 12). Normally a core
> library would not be packaged as a module but technically possible.
> So, the new thing about "modules" is, that the package manager (dnf) can
> handle this bundles like it would be a single package (handled with the
> help of metadata).

In other words, it does not have a solution for the problem mentioned above?