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<!-- The actual name of your proposed change page should look something like: Changes/Your_Change_Proposal_Name. This keeps all change proposals in the same namespace --> | <!-- The actual name of your proposed change page should look something like: Changes/Your_Change_Proposal_Name. This keeps all change proposals in the same namespace --> | ||
= DNF Make Best Mode the Default <!-- The name of your change proposal --> = | |||
{{Change_Rejected_Banner}} | |||
== Summary == | == Summary == | ||
Currently, DNF prefers clean dependency resolution over package updates; | |||
a package (almost) silently won't get updated to a newer version if the new | |||
version has dependency problems. DNF will be changed to prefer updates and fail | |||
if they have dependency resolution issues, while the failure has a temporal or permanent workaround | |||
hint for users who want to use the older behavior. | |||
== Owner == | == Owner == | ||
Line 33: | Line 16: | ||
This should link to your home wiki page so we know who you are. | This should link to your home wiki page so we know who you are. | ||
--> | --> | ||
* Name: [[User: | * Name: [[User:jmracek| Jaroslav Mracek]] | ||
<!-- Include you email address that you can be reached should people want to contact you about helping with your change, status is requested, or technical issues need to be resolved. If the change proposal is owned by a SIG, please also add a primary contact person. --> | <!-- Include you email address that you can be reached should people want to contact you about helping with your change, status is requested, or technical issues need to be resolved. If the change proposal is owned by a SIG, please also add a primary contact person. --> | ||
* Email: | * Email: jmracek@redhat.com | ||
* Release notes owner: <!--- To be assigned by docs team [[User:FASAccountName| Release notes owner name]] <email address> --> | * Release notes owner: <!--- To be assigned by docs team [[User:FASAccountName| Release notes owner name]] <email address> --> | ||
<!--- UNCOMMENT only for Changes with assigned Shepherd (by FESCo) | <!--- UNCOMMENT only for Changes with assigned Shepherd (by FESCo) | ||
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== Current status == | == Current status == | ||
* Targeted release: [[Releases/ | * Targeted release: [[Releases/31 | Fedora 31 ]] | ||
* Last updated: <!-- this is an automatic macro — you don't need to change this line --> {{REVISIONYEAR}}-{{REVISIONMONTH}}-{{REVISIONDAY2}} | * Last updated: <!-- this is an automatic macro — you don't need to change this line --> {{REVISIONYEAR}}-{{REVISIONMONTH}}-{{REVISIONDAY2}} | ||
* FESCo issue: [https://pagure.io/fesco/issue/2168 #2168] | |||
<!-- After the change proposal is accepted by FESCo, tracking bug is created in Bugzilla and linked to this page | <!-- After the change proposal is accepted by FESCo, tracking bug is created in Bugzilla and linked to this page | ||
Bugzilla states meaning as usual: | Bugzilla states meaning as usual: | ||
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== Detailed Description == | == Detailed Description == | ||
Change the built-in default value of the `best` configuration option from `0` (false) to `1` (true). | |||
As a result, unless `best` is overridden in the `/etc/dnf/dnf.conf` file or using `--setopt`, it will default to `1`. As a convenience, we will also put the explicit `best=1` assignment in the shipped `/etc/dnf/dnf.conf` file for better transparency, and introduce the new `--nobest` command-line switch. | |||
Relevant excerpt from | The purpose of the `--nobest` switch (as a shorthand for `--setopt=best=0`) is to make it easy for the user to override the default setting when needed, and it will also be [https://github.com/rpm-software-management/dnf/pull/1311/commits/9a3e8fd0da49291d30fd1fef527cffb0bf3f047d#diff-6c823931c6d150295e5011fac6529ab9R144 suggested] in the DNF output when a dependency error occurs. | ||
Relevant excerpt from the updated `dnf.conf(5)`: | |||
<pre> | <pre> | ||
best boolean | best boolean | ||
When upgrading a package, always try to install its highest version available, even only to find out some of its deps are not satisfiable. Enable this if you want to experience broken dependencies in the repositories firsthand. The default is | When upgrading a package, always try to install its highest version available, even only to find out some of its deps are not satisfiable. Enable this if you want to experience broken dependencies in the repositories firsthand. The default is True. | ||
</pre> | </pre> | ||
Relevant excerpt from | Relevant excerpt from the updated `dnf(8)`: | ||
<pre> | <pre> | ||
--nobest | --nobest | ||
Set best option as false, therefore transactions are not limited to only best candidates. | Set best option as false, therefore transactions are not limited to only best candidates. | ||
</pre> | </pre> | ||
'''Change in DNF output - missing vim-enhanced-2:8.1.1561-1.fc30''' | |||
Original output. DNF succeed with return code 0: | |||
<pre> | |||
sudo dnf upgrade | |||
Last metadata expiration check: 2:16:40 ago on Mon 24 Jun 2019 04:27:16 PM CEST. | |||
Dependencies resolved. | |||
Problem: package vim-enhanced-2:8.1.1471-1.fc30.x86_64 requires vim-common = 2:8.1.1471-1.fc30, but none of the providers can be installed | |||
- cannot install both vim-common-2:8.1.1561-1.fc30.x86_64 and vim-common-2:8.1.1471-1.fc30.x86_64 | |||
- problem with installed package vim-enhanced-2:8.1.1471-1.fc30.x86_64 | |||
- cannot install the best update candidate for package vim-common-2:8.1.1471-1.fc30.x86_64 | |||
- package vim-enhanced-2:8.1.1561-1.fc30.x86_64 is excluded | |||
=================================================================================================================================== | |||
Package Architecture Version Repository Size | |||
=================================================================================================================================== | |||
Skipping packages with conflicts: | |||
(add '--best --allowerasing' to command line to force their upgrade): | |||
vim-common x86_64 2:8.1.1561-1.fc30 updates 6.7 M | |||
Transaction Summary | |||
=================================================================================================================================== | |||
Skip 1 Package | |||
Nothing to do. | |||
Complete! | |||
</pre> | |||
Output after the change. DNF fails with return code 1, but proposing `--nobest` option as an option to resolve the issue: | |||
<pre> | |||
sudo dnf upgrade | |||
Last metadata expiration check: 2:16:36 ago on Mon 24 Jun 2019 04:27:16 PM CEST. | |||
Error: | |||
Problem: package vim-enhanced-2:8.1.1471-1.fc30.x86_64 requires vim-common = 2:8.1.1471-1.fc30, but none of the providers can be installed | |||
- cannot install both vim-common-2:8.1.1561-1.fc30.x86_64 and vim-common-2:8.1.1471-1.fc30.x86_64 | |||
- problem with installed package vim-enhanced-2:8.1.1471-1.fc30.x86_64 | |||
- cannot install the best update candidate for package vim-common-2:8.1.1471-1.fc30.x86_64 | |||
- package vim-enhanced-2:8.1.1561-1.fc30.x86_64 is excluded | |||
(try to add '--allowerasing' to command line to replace conflicting packages or '--skip-broken' to skip uninstallable packages or '--nobest' to use not only best candidate packages) | |||
</pre> | |||
'''Q&A''' | |||
Can be a default of the best configuration option overwritten easily and permanently by user? | |||
Yes, just add `best=false` to `/etc/dnf/dnf.conf` | |||
<pre> | |||
[main] | |||
best=False | |||
</pre> | |||
Can be a default of the best configuration option overwritten easily from commandline? | |||
Yes, just add `--nobest` to command | |||
<pre> | |||
dnf upgrade --nobest | |||
</pre> | |||
What about PackageKit and Gnome Software? | |||
<pre> | |||
PackageKit and Gnome Software will be not affected by the change. In case that the same behavior will be desired for PackageKit, It will require changes in PackageKit code. | |||
</pre> | |||
What about Microdnf? | |||
<pre> | |||
Microdnf will be not affected by the change. There is a plan to unify functional parity and behavior DNF with Microdnf but not before Fedora 33. | |||
</pre> | |||
== Benefit to Fedora == | == Benefit to Fedora == | ||
This change allows the | This change allows the users to be properly notified when a package cannot be upgraded to the latest version, instead of silently ignoring it as an upgrade candidate. | ||
Right now, when DNF runs in `best=0` mode, if a package cannot be upgraded due to dependency problems, it is skipped and a warning is printed in the transaction summary table. However, this poses a risk of important security fixes being overlooked by the user in case they are broken for some reason, such as due to a repository misconfiguration or inconsistency within the metadata itself. | |||
Moreover, since DNF always exits with the return code `0` (success) when in `best=0` mode, this mode is especially risky in automated scripts invoking DNF in `assumeyes` mode in which case such unsuccessful package upgrades could easily go unnoticed unless the logs are manually examined after the fact. | |||
The new behavior is also more in line with the generally accepted software development practice of failing early and failing fast. | The new behavior is also more in line with the generally accepted software development practice of failing early and failing fast. | ||
As a secondary benefit, broken upgrade paths in the Fedora repositories will hopefully be noticed, reported and therefore fixed sooner. Although, we would prefer if such problems would be detected before we ship them to users. | |||
'''Summary of benefits:''' | |||
# No silently passed problems with updates | |||
# Broken dependencies faster disappear from Fedora distribution | |||
# Problems will be reported more often - opportunity to fix issues | |||
# Increase in stability of Fedora distribution | |||
# Less issues after branching | |||
# Identical behavior of DNF in all distributions - Fedora/RHEL/Mageia/OpenSuse | |||
== Scope == | == Scope == | ||
* Proposal owners: | * Proposal owners: | ||
The change is already part of the upstream (dnf-4.1.0) and reverted in Fedora downstream. The change was composed by following pull requests: | |||
https://github.com/rpm-software-management/libdnf/pull/678<br> | https://github.com/rpm-software-management/libdnf/pull/678<br> | ||
Line 91: | Line 157: | ||
https://github.com/rpm-software-management/dnf/pull/1316<br> | https://github.com/rpm-software-management/dnf/pull/1316<br> | ||
https://github.com/rpm-software-management/dnf/pull/1319 | https://github.com/rpm-software-management/dnf/pull/1319 | ||
We would like to stop the reverting the changes. | |||
* Other developers: N/A (not a System Wide Change) <!-- REQUIRED FOR SYSTEM WIDE CHANGES --> | * Other developers: N/A (not a System Wide Change) <!-- REQUIRED FOR SYSTEM WIDE CHANGES --> | ||
Line 132: | Line 200: | ||
== User Experience == | == User Experience == | ||
Broken upgrades are recognized early, enabling the | Broken upgrades are recognized early, enabling the users to act upon them by double-checking their repository configuration or filing bugs, instead of assuming no upgrades are available. | ||
== Dependencies == | == Dependencies == | ||
Line 141: | Line 209: | ||
== Contingency Plan == | == Contingency Plan == | ||
If there is a massive negative feedback by the rawhide and pre-beta users, we can revert the | |||
change at the beta freeze. If there is a massive negative feedback by the beta users, we can | |||
revert the change at final freeze. | |||
<!-- If you cannot complete your feature by the final development freeze, what is the backup plan? This might be as simple as "Revert the shipped configuration". Or it might not (e.g. rebuilding a number of dependent packages). If you feature is not completed in time we want to assure others that other parts of Fedora will not be in jeopardy. --> | <!-- If you cannot complete your feature by the final development freeze, what is the backup plan? This might be as simple as "Revert the shipped configuration". Or it might not (e.g. rebuilding a number of dependent packages). If you feature is not completed in time we want to assure others that other parts of Fedora will not be in jeopardy. --> |
Latest revision as of 17:56, 18 July 2023
DNF Make Best Mode the Default
Summary
Currently, DNF prefers clean dependency resolution over package updates; a package (almost) silently won't get updated to a newer version if the new version has dependency problems. DNF will be changed to prefer updates and fail if they have dependency resolution issues, while the failure has a temporal or permanent workaround hint for users who want to use the older behavior.
Owner
- Name: Jaroslav Mracek
- Email: jmracek@redhat.com
- Release notes owner:
Current status
- Targeted release: Fedora 31
- Last updated: 2023-07-18
- FESCo issue: #2168
- Tracker bug: <will be assigned by the Wrangler>
Detailed Description
Change the built-in default value of the best
configuration option from 0
(false) to 1
(true).
As a result, unless best
is overridden in the /etc/dnf/dnf.conf
file or using --setopt
, it will default to 1
. As a convenience, we will also put the explicit best=1
assignment in the shipped /etc/dnf/dnf.conf
file for better transparency, and introduce the new --nobest
command-line switch.
The purpose of the --nobest
switch (as a shorthand for --setopt=best=0
) is to make it easy for the user to override the default setting when needed, and it will also be suggested in the DNF output when a dependency error occurs.
Relevant excerpt from the updated dnf.conf(5)
:
best boolean When upgrading a package, always try to install its highest version available, even only to find out some of its deps are not satisfiable. Enable this if you want to experience broken dependencies in the repositories firsthand. The default is True.
Relevant excerpt from the updated dnf(8)
:
--nobest Set best option as false, therefore transactions are not limited to only best candidates.
Change in DNF output - missing vim-enhanced-2:8.1.1561-1.fc30
Original output. DNF succeed with return code 0:
sudo dnf upgrade Last metadata expiration check: 2:16:40 ago on Mon 24 Jun 2019 04:27:16 PM CEST. Dependencies resolved. Problem: package vim-enhanced-2:8.1.1471-1.fc30.x86_64 requires vim-common = 2:8.1.1471-1.fc30, but none of the providers can be installed - cannot install both vim-common-2:8.1.1561-1.fc30.x86_64 and vim-common-2:8.1.1471-1.fc30.x86_64 - problem with installed package vim-enhanced-2:8.1.1471-1.fc30.x86_64 - cannot install the best update candidate for package vim-common-2:8.1.1471-1.fc30.x86_64 - package vim-enhanced-2:8.1.1561-1.fc30.x86_64 is excluded =================================================================================================================================== Package Architecture Version Repository Size =================================================================================================================================== Skipping packages with conflicts: (add '--best --allowerasing' to command line to force their upgrade): vim-common x86_64 2:8.1.1561-1.fc30 updates 6.7 M Transaction Summary =================================================================================================================================== Skip 1 Package Nothing to do. Complete!
Output after the change. DNF fails with return code 1, but proposing --nobest
option as an option to resolve the issue:
sudo dnf upgrade Last metadata expiration check: 2:16:36 ago on Mon 24 Jun 2019 04:27:16 PM CEST. Error: Problem: package vim-enhanced-2:8.1.1471-1.fc30.x86_64 requires vim-common = 2:8.1.1471-1.fc30, but none of the providers can be installed - cannot install both vim-common-2:8.1.1561-1.fc30.x86_64 and vim-common-2:8.1.1471-1.fc30.x86_64 - problem with installed package vim-enhanced-2:8.1.1471-1.fc30.x86_64 - cannot install the best update candidate for package vim-common-2:8.1.1471-1.fc30.x86_64 - package vim-enhanced-2:8.1.1561-1.fc30.x86_64 is excluded (try to add '--allowerasing' to command line to replace conflicting packages or '--skip-broken' to skip uninstallable packages or '--nobest' to use not only best candidate packages)
Q&A
Can be a default of the best configuration option overwritten easily and permanently by user?
Yes, just add best=false
to /etc/dnf/dnf.conf
[main] best=False
Can be a default of the best configuration option overwritten easily from commandline?
Yes, just add --nobest
to command
dnf upgrade --nobest
What about PackageKit and Gnome Software?
PackageKit and Gnome Software will be not affected by the change. In case that the same behavior will be desired for PackageKit, It will require changes in PackageKit code.
What about Microdnf?
Microdnf will be not affected by the change. There is a plan to unify functional parity and behavior DNF with Microdnf but not before Fedora 33.
Benefit to Fedora
This change allows the users to be properly notified when a package cannot be upgraded to the latest version, instead of silently ignoring it as an upgrade candidate.
Right now, when DNF runs in best=0
mode, if a package cannot be upgraded due to dependency problems, it is skipped and a warning is printed in the transaction summary table. However, this poses a risk of important security fixes being overlooked by the user in case they are broken for some reason, such as due to a repository misconfiguration or inconsistency within the metadata itself.
Moreover, since DNF always exits with the return code 0
(success) when in best=0
mode, this mode is especially risky in automated scripts invoking DNF in assumeyes
mode in which case such unsuccessful package upgrades could easily go unnoticed unless the logs are manually examined after the fact.
The new behavior is also more in line with the generally accepted software development practice of failing early and failing fast.
As a secondary benefit, broken upgrade paths in the Fedora repositories will hopefully be noticed, reported and therefore fixed sooner. Although, we would prefer if such problems would be detected before we ship them to users.
Summary of benefits:
- No silently passed problems with updates
- Broken dependencies faster disappear from Fedora distribution
- Problems will be reported more often - opportunity to fix issues
- Increase in stability of Fedora distribution
- Less issues after branching
- Identical behavior of DNF in all distributions - Fedora/RHEL/Mageia/OpenSuse
Scope
- Proposal owners:
The change is already part of the upstream (dnf-4.1.0) and reverted in Fedora downstream. The change was composed by following pull requests:
https://github.com/rpm-software-management/libdnf/pull/678
https://github.com/rpm-software-management/dnf/pull/1311
https://github.com/rpm-software-management/dnf/pull/1316
https://github.com/rpm-software-management/dnf/pull/1319
We would like to stop the reverting the changes.
- Other developers: N/A (not a System Wide Change)
- Release engineering: #Releng issue number (a check of an impact with Release Engineering is needed)
- List of deliverables: N/A (not a System Wide Change)
- Policies and guidelines: N/A (not a System Wide Change)
- Trademark approval: N/A (not needed for this Change)
Upgrade/compatibility impact
N/A (not a System Wide Change)
How To Test
N/A (not a System Wide Change)
User Experience
Broken upgrades are recognized early, enabling the users to act upon them by double-checking their repository configuration or filing bugs, instead of assuming no upgrades are available.
Dependencies
N/A (not a System Wide Change)
Contingency Plan
If there is a massive negative feedback by the rawhide and pre-beta users, we can revert the change at the beta freeze. If there is a massive negative feedback by the beta users, we can revert the change at final freeze.
- Contingency mechanism: (What to do? Who will do it?) N/A (not a System Wide Change)
- Contingency deadline: N/A (not a System Wide Change)
- Blocks release? N/A (not a System Wide Change), Yes/No
- Blocks product? product
Documentation
N/A (not a System Wide Change)