dnf replacing yum and dnf-yum

[Pete Travis]

On Apr 13, 2015 5:07 AM, "Radek Holy" <rholy at redhat.com> wrote:
>
>
> ________________________________
>>
>> From: "Pete Travis" <lists at petetravis.com>
>> To: "Development discussions related to Fedora" <
devel at lists.fedoraproject.org>
>> Sent: Friday, April 10, 2015 5:31:08 PM
>> Subject: Re: dnf replacing yum and dnf-yum
>>
>>
>>
>> On Apr 10, 2015 4:39 AM, "Radek Holy" <rholy at redhat.com> wrote:
>> >
>>
>> >
>> > Hm, I think that it depends on the use case. AFAIK, distro-sync is
mostly used to upgrade Fedora (an unsupported approach AFAIK) and to
replace some testing/3rd-party versions of package with the "official"
ones. (BTW, I'd appreciate if anyone will share their use case) While in
the first case, I think that the upgrade's behaviour is preferred, in the
other case, the install's behaviour is better IMO. (Which dangerously
indicates that the --skip-broken switch is a good solution :( )
>> >
>> > Anyway, file an RFE (if it isn't filed already) please. We can
track/discuss it there.
>> >
>> > Thank you in advance
>> > --
>> > Radek Holý
>> >
>>
>> (lots of trimming, and skipping an RFE, as this just pertains to the
distro-sync use case question)
>>
>> distro-sync is useful for getting to a sane state after temporarily
enabling some repo that interacts with the primary ones.  This can happen
with third party repos, but we can consider an entirely in-house situation:
>>
>> The user finds a bug in widget-2.5.7 and reports it.  A fix for widget
is shipped and the user is asked to test via `dnf update widget
--enablerepo updates-testing`.  The transaction pulls in many requires from
updates-testing (although at this point, I realize dnf may not be upgrading
the requires in this transaction if they are not versioned).  The new
widget is tested, life goes on.
>>
>> Later, the user wants to install or update some package whizbang that
shares requires with widget.  That package has versioned requires on
packages from the updates repo, but some of the installed packages are from
updates-testing and don't provide what whizbang needs.
>>
>> Something like `dnf --allowerasing install whizbang` might be the
appropriate and precise tool to get through that transaction.  `dnf
distro-sync` is the less precise, big-hammer tool for the user that doesn't
know or care to track down the intricacies of widget and whizbang
dependencies.   They ran some command from a bug report a while ago and
moved on, and now they run distro-sync to return their system to a
known-good state and move on.
>>
>> This sort of thing is most common during the prerelease cycle, when
users will have updates-testing on then off, and there are freezes, and
branching, and lots of activity that might leave early adopters in an
unsane state.
>>
>> And yeah, it is very useful for upgrades.  Even when ran after a proper
fedup upgrade.
>>
>> --Pete
>>
>>
> Yeah, that's basically what I meant by 'replace some testing versions of
package with the "official" ones'. Anyway, thank you for elaborating on it.
I'll definitely make a test case from it.
>
> I'd like to let those doing the actions described above know that there
is also a not very well known command "dnf repository-packages <repoid>
remove-or-distro-sync" which is specifically designed for switching from
packages installed from testing/3rd-party repositories
> --
> Radek Holý
> Associate Software Engineer
> Software Management Team
> Red Hat Czech
>
> --

Nice! That's <repoid> as the stable/updates repo, not the
testing/3rd-party/problem repo, right? I'll add this to my dnf writeup.

--Pete
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