This is a tracking bug for Change: Replace Yum With DNF
For more details, see: https://fedoraproject.org//wiki/Changes/ReplaceYumWithDNF
Make DNF (Dandified Yum)/Yum4 the new default packaging tool in F22.
Marking 1183835 as blocking this because I'm not convinced by 'oh, just fix it with an RPM feature we don't have yet, in potentially dozens of packages' as an approach to dealing with a situation where dnf's behaviour is clearly inferior to yum's.
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I claim that DNF is stable and ready to go to F22. Differences between DNF and yum are documented here .
WRT yum plugins, most of the yum-utils are ported to DNF . We are working on porting the rest.
From Fedora 22 Server x86_64 (base) the packages depending on yum are:
rolekit - patch posted here  and update is coming soon.
libreport-python - port is almost finished, only one DNF feature is needed  (PR created).
In Fedora 22 Cloud x86_64 there are no packages requiring yum.
Some core components from Fedora 22 Workstation already rely on DNF:
* openlmi-providers - not requires DNF itself but shares DNF core libraries
* gnome-software - not requires DNF itself but shares DNF core libraries
Switching back to yum backend would need to revert these changes.
Since Python 2 is still default in F22, DNF will run on it as well. However DNF is ready to run on Python 3 - it's matter of one line change.
The heuristic of choosing provides (bug 1192225 and bug 1183835 referenced by Adam) will be improved in libsolv (depsolver) too .
To be fair I am referencing again the tracker bug 1156491 of all non-core components depending on yum/yum-utils which are currently being ported.
rolekit package has been switched to use DNF - see http://koji.fedoraproject.org/koji/buildinfo?buildID=614325
I wrote some copy about this change at https://fedoraproject.org/wiki/Documentation_Server_Configuration_Tools_Beat#yum_replaced_by_dnf - feedback and edits welcome.
Can we clarify the plans for yum-dnf?
The change page indicates it should be installed by default in f22, and it's not.
If we do install it, it will break all those things still not ported over to dnf.
IMHO, it shouldn't be ever installed by default, but if change owners/fesco agree, we should adjust the change page on the wiki to no longer refer to it.
> Can we clarify the plans for yum-dnf?
> The change page indicates it should be installed by default in f22, and it's
As far as I can see in my Fedora 22 Alpha installation dnf is installed by default. So the change page is correct.
> If we do install it, it will break all those things still not ported over to
All packages in Cloud or minimal Server or Workstation installation depends on dnf. Not ported packages can still pull in yum as their dependency so nothing breaks.
(In reply to Michael Mráka from comment #8)
> > Can we clarify the plans for yum-dnf?
> > The change page indicates it should be installed by default in f22, and it's
> > not.
> As far as I can see in my Fedora 22 Alpha installation dnf is installed by
> default. So the change page is correct.
You misunderstand. I was talking about "yum-dnf" which is a subpackage that replaces /usr/bin/yum with a call to dnf. That is NOT installed by default anywhere (but the change page says it will be).
> > If we do install it, it will break all those things still not ported over to
> > dnf.
> All packages in Cloud or minimal Server or Workstation installation depends
> on dnf. Not ported packages can still pull in yum as their dependency so
> nothing breaks.
Unless dnf-yum is installed, because it conflicts with yum and then you would be unable to install.
This message is a reminder that Fedora 22 "Change Checkpoint: 100% Code Complete Deadline" is on 2015-03-31 .
All Accepted Changes has to be code complete and ready to be validated in the Beta release (optionally by Fedora QA). Required bug state at this point is ON_QA.
As for several System Wide Changes, Beta Freeze is a point of contingency plan, all incomplete Changes will be reported to FESCo for 2015-04-01 meeting. In case of any questions, don't hesitate to ask Wrangler (jreznik).
* python-libreport does not depend on yum
* dnf-yum package does not conflict with yum and /usr/bin/yum executable runs DNF 
* dnf migration plugin was made to transfer package, groups and transaction metadata from yum to DNF
All changes are in updates (bug 1207726)