Latest revision as of 12:34, 9 February 2024

DNF: Do not download filelists by default

Summary

Change the DNF behavior to not download filelists by default. These metadata, which describe all the files contained within each package, are unnecessary in the majority of use cases. Additionally, these metadata files can be large in size, leading to a significant slowdown in the user experience.

Owner

Name: Jan Kolarik
Email: jkolarik@redhat.com

Current status

Targeted release: Fedora Linux 40
Last updated: 2024-02-09
Announced
Discussion thread
FESCo issue: #3097
Tracker bug: #2254789
Release notes tracker: #1064

Detailed Description

Until now, filelists were always downloaded together with other metadata. This was hardcoded and unable to change from the outside of DNF.

With these changes, we are proposing to not download the filelists metadata by default. This default behavior can be modified through the new DNF configuration option. Additionally, specific commands can override this behavior and request loading the filelists metadata at runtime using the existing demands object in DNF.

Note that after this change, users can still use DNF without filelists metadata when querying file provides located in /usr/bin, /usr/sbin or /etc directories.

The proposed behavior has already been incorporated into the future successor, DNF5 project, where they were implemented around the beginning of this year (see this PR for more details).

Feedback

Benefit to Fedora

As DNF is integral to various infrastructure tasks like package building and installation, testing environment creation, and server integration tests, this change significantly reduces processing time and resource usage for these processes.

This change reduces the RAM requirements of the DNF process, addressing existing issues when running the Fedora system on low-memory machines such as the Raspberry Pi (see f.e. Bug 1907030).

Also, omitting the filelists metadata download overall decreases the costs of a Fedora mirror server operation.

As the described behavior already exists in its extended form in DNF5 within the current Fedora release, allowing any optional metadata types to be conditionally loaded, and considering that DNF5 is planned to replace DNF as the main package manager for Fedora 41, implementing these changes will facilitate a smoother and more compatible transition process.

Scope

Proposal owners:
- libdnf
  - Modify the Repo object to enable conditional filelists metadata download
  - Introduce a new main configuration option to set the default behavior
- dnf
  - Enable configuration of filelists download from commandline, DNF commands and DNF plugins
  - Implement filename pattern argument detection heuristics

Other developers:
- Dependencies using the existing DNF C interface may need to adapt if they expect the filelists metadata to be available and explicitly request loading filelists using the existing API due to this change:
  - PackageKit
  - microdnf
  - API users

Release engineering: N/A

Policies and guidelines:
- Package maintainers must follow Fedora's packaging guidelines, particularly concerning file dependency specifications (see here)
  - Adopting the MUST NOT rule in these guidelines would help prevent future issues with the installability of such packages.
  - A few packages in the current Fedora developmental release are not following these rules. Pull requests have already been prepared to fix their spec files. Please refer to Bug 2180842 for details.

Trademark approval: N/A

Alignment with Community Initiatives: N/A (no currently active initiatives)

Upgrade/compatibility impact

In general, applying these changes should not affect any existing user workflows and no additional manual changes are required.

However, the absence of filelists would cause issues for packages that do not follow the recommended file dependencies outlined in the packaging guidelines. This change would render such packages uninstal‌lable without the presence of filelists. In the current Fedora release repository, only a few packages are affected, and none of them is critical to the system. Also, trivial pull requests have already been prepared for each, resolving the issue upon merging.

If DNF fails to resolve a transaction due to a missing file dependency, and the filelists metadata are not currently present on the system, users will receive a hint on how to request the download of filelists from the command line. This action may assist in resolving the situation.

For more information, refer to the Bug 2180842 and the discussion thread on this proposal.

How To Test

When using DNF commands without a filename pattern passed as the argument, filelists metadata should not be downloaded from the remote repositories and should not be needed for the command execution. This can be tested with the following steps:

Clean the local metadata cache (dnf clean metadata)
Run a DNF command not involving the filename spec (e.g. dnf repoquery rpm)
Verify that no *-filelists.* metadata files were downloaded inside the cache subdirectories (by default under the /var/cache/dnf for root)
Check the command works as expected

The same should also apply to RPM package arguments (files ending with .rpm extension).

When using DNF commands with a filename pattern passed as the argument, filelists metadata should be downloaded from the remote repositores as before.

User Experience

Large filelists could be over 200MB in size. It could take 1-2 minutes to download which is greatly slowing down the user experience.

For many operations the filelists metadata are not needed, so downloading them is wasting the resources. Without filelists being downloaded, DNF performance will be improved significantly, mainly regarding the network, CPU and disk space resources. Metadata download size will be reduced by about 60%. The improvement includes deployments of customer built RPMS to containers that have no need for filelists level dependencies.

Dependencies

No changes should be required for any package depending on DNF to implement this behavior.

Contingency Plan

Contingency mechanism: Change the configuration option to download the filelists by default
Contingency deadline: Branch Fedora Linux 40 from Rawhide
Blocks release? No

Documentation

New configuration option optional_metadata_types was added to allow requesting filelists metadata on demand, see configuration docs here.

Release Notes

@@ Line 1: / Line 1: @@
-{{admon/important | Comments and Explanations | The page source contains comments providing guidance to fill out each section. They are invisible when viewing this page. To read it, choose the "view source" link.<br/> '''Copy the source to a ''new page'' before making changes!  DO NOT EDIT THIS TEMPLATE FOR YOUR CHANGE PROPOSAL.'''}}
-{{admon/tip | Guidance | For details on how to fill out this form, see the [https://docs.fedoraproject.org/en-US/program_management/changes_guide/ documentation].}}
-{{admon/tip | Report issues | To report an issue with this template, file an issue in the [https://pagure.io/fedora-pgm/pgm_docs pgm_docs repo].}}
-<!-- 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: Do not download filelists by default <!-- The name of your change proposal --> =
-{{Change_Proposal_Banner}}
 == Summary ==
@@ Line 27: / Line 17: @@
 == Current status ==
-[[Category:ChangePageIncomplete]]
+[[Category:ChangeAcceptedF40]]
 <!-- When your change proposal page is completed and ready for review and announcement -->
 <!-- remove Category:ChangePageIncomplete and change it to Category:ChangeReadyForWrangler -->
@@ Line 34: / Line 24: @@
 <!-- Select proper category, default is Self Contained Change -->
-[[Category:SelfContainedChange]]
+[[Category:SystemWideChange]]
 <!-- [[Category:SystemWideChange]] -->
@@ Line 45: / Line 35: @@
 ON_QA -> change is fully code complete
 -->
-* [<will be assigned by the Wrangler> devel thread]
+* [https://lists.fedoraproject.org/archives/list/devel-announce@lists.fedoraproject.org/thread/5UFFIAR5ITBS7YFS4N5HM5GGPXYVPF7E/ Announced]
-* FESCo issue: <will be assigned by the Wrangler>
+* [https://discussion.fedoraproject.org/t/f40-change-proposal-dnfconditionalfilelists-system-wide/94939 Discussion thread]
-* Tracker bug: <will be assigned by the Wrangler>
+* FESCo issue: [https://pagure.io/fesco/issue/3097 #3097]
-* Release notes tracker: <will be assigned by the Wrangler>
+* Tracker bug: [https://bugzilla.redhat.com/show_bug.cgi?id=2254789 #2254789]
+* Release notes tracker: [https://pagure.io/fedora-docs/release-notes/issue/1064 #1064]
 == Detailed Description ==
@@ Line 56: / Line 47: @@
 Note that after this change, users can still use DNF without filelists metadata when querying file provides located in `/usr/bin`, `/usr/sbin` or `/etc` directories.
+The proposed behavior has already been incorporated into the future successor, DNF5 project, where they were implemented around the beginning of this year (see [https://github.com/rpm-software-management/dnf5/pull/123 this PR] for more details).
 == Feedback ==
@@ Line 62: / Line 55: @@
 == Benefit to Fedora ==
 As DNF is integral to various infrastructure tasks like package building and installation, testing environment creation, and server integration tests, this change significantly reduces processing time and resource usage for these processes.
+This change reduces the RAM requirements of the DNF process, addressing existing issues when running the Fedora system on low-memory machines such as the Raspberry Pi (see f.e. [https://bugzilla.redhat.com/show_bug.cgi?id=1907030 Bug 1907030]).
+Also, omitting the filelists metadata download overall decreases the costs of a Fedora mirror server operation.
+As the described behavior already exists in its extended form in DNF5 within the current Fedora release, allowing any optional metadata types to be conditionally loaded, and considering that DNF5 is planned to replace DNF as the main package manager for Fedora 41, implementing these changes will facilitate a smoother and more compatible transition process.
 == Scope ==
@@ Line 69: / Line 68: @@
 *** Introduce a new main configuration option to set the default behavior
 ** dnf
-*** Introduce a new demand to enable specific commands to override filelists metadata download behavior
+*** Enable configuration of filelists download from commandline, DNF commands and DNF plugins
-*** Handle demand and configuration option inputs to delegate filelists loading decision to `libdnf`
 *** Implement filename pattern argument detection heuristics
 * Other developers: <!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
-** Dependencies using the existing DNF C interface may need to adapt and explicitly request loading filelists using the existing API due to this change:
+** Dependencies using the existing DNF C interface may need to adapt if they expect the filelists metadata to be available and explicitly request loading filelists using the existing API due to this change:
 *** PackageKit
 *** microdnf
@@ Line 83: / Line 81: @@
 * Policies and guidelines:
 ** Package maintainers must follow Fedora's packaging guidelines, particularly concerning file dependency specifications (see [https://docs.fedoraproject.org/en-US/packaging-guidelines/#_file_and_directory_dependencies here])
+*** Adopting the '''MUST NOT''' rule in these guidelines would help prevent future issues with the installability of such packages.
+*** A few packages in the current Fedora developmental release are not following these rules. Pull requests have already been prepared to fix their spec files. Please refer to [https://bugzilla.redhat.com/show_bug.cgi?id=2180842 Bug 2180842] for details.
 * Trademark approval: N/A
@@ Line 91: / Line 91: @@
 == Upgrade/compatibility impact ==
-In general, applying these changes should not affect any existing user workflows and no additional manual changes are required. However, the absence of filelists might create an issue with packages that are not correctly packaged, f.e. from third-party repositories.
+In general, applying these changes should not affect any existing user workflows and no additional manual changes are required.
+However, the absence of filelists would cause issues for packages that do '''not''' follow the recommended file dependencies outlined in the [https://docs.fedoraproject.org/en-US/packaging-guidelines/#_file_and_directory_dependencies packaging guidelines]. This change would render such packages uninstal‌lable without the presence of filelists. In the current Fedora release repository, only a few packages are affected, and none of them is critical to the system. Also, trivial pull requests have already been prepared for each, resolving the issue upon merging.
+If DNF fails to resolve a transaction due to a missing file dependency, and the filelists metadata are not currently present on the system, users will receive a hint on how to request the download of filelists from the command line. This action may assist in resolving the situation.
+For more information, refer to the [https://bugzilla.redhat.com/show_bug.cgi?id=2180842 Bug 2180842] and the [https://discussion.fedoraproject.org/t/f40-change-proposal-dnfconditionalfilelists-system-wide/94939 discussion thread] on this proposal.
 == How To Test ==
@@ Line 119: / Line 125: @@
 == Dependencies ==
-No changes should be required for any package depending on DNF.
+No changes should be required for any package depending on DNF to implement this behavior.
 == Contingency Plan ==
@@ Line 127: / Line 133: @@
 == Documentation ==
-Links to the relevant DNF CLI and API documentation sections will be provided here once the related pull request is created.
+New configuration option `optional_metadata_types` was added to allow requesting filelists metadata on demand, see configuration docs [https://dnf.readthedocs.io/en/latest/conf_ref.html#optional-metadata-types-label here].
 == Release Notes ==

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