Re: [Modularity] Module streams with two different, non-overlapping, package sets?

[Petr Šabata]

On Wed, Jun 20, 2018 at 02:15:00PM +0200, Severin Gehwolf wrote:
>  On Wed, 2018-06-20 at 07:59 -0400, Josh Boyer wrote:
>  > On Wed, Jun 20, 2018 at 7:52 AM Severin Gehwolf <sgehwolf(a)redhat.com&gt; wrote:
>  > > 
>  > > Hi,
>  > > 
>  > > I'm exploring the Fedora Modularity world and would like to know
>  > > whether it's possible to have two different module streams install two
>  > > different sets of packages? If that's possible, would installing one
>  > > stream remove the packages from the other stream even though the set of
>  > > packages don't overlap? I'm aware that it's not a goal of
> modularity to
>  > > support parallel installability. But what if the packages themselves
>  > > already allow parallel installability?
>  > > 
>  > > Example:
>  > > 
>  > > Module name: jdk
>  > > Streams: 8, 11
>  > > 
>  > > 1) "dnf module install jdk:8/default" installs these packages:
>  > > 
>  > > java-1.8.0-openjdk
>  > > java-1.8.0-openjdk-devel
>  > > java-1.8.0-openjdk-headless
>  > > 
>  > > 2) "dnf module install jdk:11/default" installs these packages:
>  > > 
>  > > java-11-openjdk
>  > > java-11-openjdk-headless
>  > > java-11-openjdk-devel
>  > > 
>  > > After 1) *and* 2) would I have both module streams' packages on my
>  > > system? Would I have only the set from 2) with 1) removed?
>  > 
>  > I think you would only have the set from 2.
>  > 
>  > Parallel installation can't be done via streams, so it must be done at
>  > the module level.  So you'd have jdk8 and jdk11 modules, each with a
>  > default stream.  Given the default is specified, an installation would
>  > look something like:
>  > 
>  > "dnf module install jdk8; dnf module install jdk11"
>  
>  That's interesting, thanks!
>  
>  FWIW, I've tried the reverse :) I had jdk10 and jdk11 both specifying
>  packages java-openjdk{,-devel,-headless} and the install of jdk11
>  *upgraded* packages from the other (jdk10) module. 
You could still do it with streams and simply encourage users
who need both to use containers, one with each stream stream
enabled :)

Parallel installation of streams on a single system indeed
isn't supported at this point and isn't planned anytime in the
near future.  In general it's a more complicated problem than
it might seem at first.

P