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How can I know WHY dnf pulls in packages, or sees a conflict?

asked 2014-10-01 15:54:35 -0600

goeran gravatar image

Sometimes when I do an install of a package, dnf pulls in a lot of other, seemingly unrelated packages. Sometimes when I try some non-standard package combination, dnf replies it can't do it because

package X requires Y but none of the providers can be installed

where neither X nor Y appears to be related to the package I try to install.

Is there a way to ask dnf to explain why it's doing what it's doing? With yum you could get an explanation with a lot of lines like

Processing Dependency: A for package: B Package C will be updated

Where C typically provides A. And so on. By studying these messages, I were able to figure out the unexpected dependencies and decide what to do.

But dnf doesn't seem to have anything similar. I've looked at the output form --debugsolver, but it doesn't seem to help. Is there a way to figure this out with dnf?

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answered 2014-10-01 16:07:41 -0600

mether gravatar image

updated 2014-10-01 17:26:36 -0600

You should try dnf -v for more verbosity. For example dnf -v install package-name

However also read https://rpm-software-management.github.io/dnf/cli_vs_yum.html#dependency-processing-details-are-not-shown-in-the-cli

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I should have said I had tried -v. But it doesn't answer this particular question.

Maybe I misunderstood the web page you refer to. I thought it meant that the output had been reduced to remove confusion and verbosity. That makes sense, It shouldn't be there by default. But reading the bug referred once more, maybe it means there is no way to get the information. Is that what it says?

(While yum still is available, I guess I could use that tool to get the information. But I suppose that is not a permanent solution, yum will be phased out I suppose.)

goeran gravatar imagegoeran ( 2014-10-01 16:31:54 -0600 )edit

@goeran, dnf internals at this point are quite different and I am not sure that info is readily available but if you have requirements that are unsatisfied, you should file a bug report/enhancement request in bugzilla

mether gravatar imagemether ( 2014-10-01 17:08:45 -0600 )edit

Ok, got it. Thanks!

goeran gravatar imagegoeran ( 2014-10-01 17:15:47 -0600 )edit

I have filed a bug report at https://bugzilla.redhat.com/show_bug.cgi?id=1148627 . Hope that helps.

mether gravatar imagemether ( 2014-10-01 17:49:41 -0600 )edit
FranciscoD_ gravatar imageFranciscoD_ ( 2014-10-03 03:28:23 -0600 )edit
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answered 2014-10-01 16:30:57 -0600

msuchy gravatar image
dnf upgrade --best
dnf install --best

This will alway force latest available version and possibly fail giving a reason why the latest version can not be installed.

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It forces the latest version, but the reason often is of the form

package X requires Y but none of the providers can be installed

where both X and Y appears unrelated to the package I'm installing, as I described above.

goeran gravatar imagegoeran ( 2014-10-01 16:34:02 -0600 )edit

@goeran it would be easier to demonstrate what's going on and how to explain it if you would be specific about the packages involved.

randomuser gravatar imagerandomuser ( 2014-10-01 18:44:39 -0600 )edit

I wasn't very specific since I didn't want a reply to the question "what is wrong" but to the question "how can I find out what is wrong". It was help in getting information out of dnf/hawkey/libsolv I wanted.

I was going to file a bugzilla, but Rahul beat me to it. I've added a concrete example as a comment in it.

goeran gravatar imagegoeran ( 2014-10-02 15:22:53 -0600 )edit
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answered 2014-10-02 17:13:03 -0600

FeRDNYC gravatar image

The dnf developers made an implementation decision not to "show their work" by emitting "Processing" lines, which they claim is a feature.

In this closed Fedora bug from 2013-12-19, Ales Kozumplik makes the following assertion:

Yum shows these 'Processing Dependency' lines but they do more confusion than good. I'll document this properly so people know we don't do it on purpose.

(By which he means, "we purposely don't do it".)

The "more confusion than good" argument — a personal-opinion/bias sounding claim (IMHO) which is never justified or even furnished with any supporting evidence — I find extremely dubious, as it directly contradicts my own 10+ years of Fedora package management experience and observations.

I can think of several scenarios (including the one in your question) where yum's "Processing..." lines are quite useful, for practical reasons (not mere "user curiosity"). And although I'm sure at least one instance of someone, somewhere being confused by them has occurred throughout yum's history, the idea that this is a common problem, or one which outweighs their usefulness, is very much [citation needed].

However, multiple requests (see the same bug) to reconsider that decision, or at least provide some rationale for it, have been ignored.

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Ales is no longer leading the project and more open bug reports have been filed (refer to the one I filed and referenced here). We may get some progress.

mether gravatar imagemether ( 2014-10-02 17:31:19 -0600 )edit

Interesting, thanks for the info. Here's hoping. I was finding it extremely troubling that dnf was being positioned as "a yum rewrite", while at the same time useful and desired features from yum were being consciously and explicitly removed/excluded, on no stronger justification than "we don't think you need this".

...In the interest of civility (mostly mine, as I doubt I'd be able to resist profanity), I shall refrain from drawing any parallels to desktop environments.

FeRDNYC gravatar imageFeRDNYC ( 2014-10-02 18:37:13 -0600 )edit

I wouldn't want Ask Fedora to be a discussion forum but do write me an email with any missing features you find useful and I will try to keep track of that before the replacement happens. Thanks

mether gravatar imagemether ( 2014-10-02 18:40:03 -0600 )edit

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Asked: 2014-10-01 15:54:35 -0600

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Last updated: Oct 02 '14