Suppose user enabled module perl-DBD-SQLite:1.58
# dnf module reset perl-DBD-SQLite
# dnf module enable perl-DBD-SQLite
At this point user enabled all modules: "perl-DBD-SQLite" that have stream "1.58"
Next user wants to install specific version of module "perl-DBD-SQLite" specifying: NSVC
# dnf module install perl-DBD-SQLite:1.58:8010020190322125518:e74546ca
Remember? Module is enabled.
But this command will fail. Because required modules are not installed:
Modulemd for perl-DBD-SQLite:1.58:8010020190322125518:e74546ca has:
DNF doesn't print any understanding explanation, why NSVC cannot be installed. However, module is enabled.
Currently user must also do:
# dnf module reset perl
# dnf module enable perl:5.24
This is not obvious. Child-module-expansion must install required parent-modules.
Otherwise, user cannot understand why module is enabled but is not installable.
I doubt that user will go and read read modulemd for perl-DBD-SQLite what it requires.
If you do not want to do this, than please, just print some useful info such as:
Requirements to install perl-DBD-SQLite:1.58:8010020190322125518:e74546ca is not satisfied.
Missing required installed modules:
I investigated the issue, and I found that the problem is caused by preferring of a context using default stream. This is more restrictive behaviorDue to latest changes that should not allow stream switch I would not recommend to change the behavior.
The issue could be resolved enabling perl:5.24 manually.
I agree that "The issue could be resolved enabling perl:5.24 manually."
But, problem is users doesn't know that he needs enable perl:5.24 manually. Or Perl:5.26 or perl:6.01
DNF doesn't give any clue/hint why it fails.
There should be some meaningful info from DNF. something like: this NSVC has next requires:
| # DEPENDENCY |
| Modules to be enabled: |
| * perl:5.24 |
| * perl-DBI:1.641 |
1. user will blame DNF.
2. user mast manually inspect md file to figure out why it fails.
Now DNF fails in very unfriendly manner.
Hope for your understanding.
We need an opinion about required behavior from Modularity team.
I agree the current behavior is a consequence of the restrictive stream switching behavior and should be kept.
However, I also agree DNF should provide some more information to guide the user in the right direction; even if just by saying that the required context is available but couldn't be installed because of unment module-level dependencies. Would that be possible?
I enhanced the error message (see output bellow) - https://github.com/rpm-software-management/dnf/pull/1532. Please do you agree with proposed solution?
# dnf module install perl-DBI:1.641:820190116185335:082fdf2f
All matches for argument 'perl-DBI:1.641:820190116185335:082fdf2f' in module 'perl-DBI:1.641' are not active
Error: Problems in request:
broken groups or modules: perl-DBI:1.641:820190116185335:082fdf2f
It looks match better now. Thank you.
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.
For information on the advisory, and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.