Changes/RelocateRPMDNFToUsr

Relocate RPM/DNF databases to /usr

Summary

Currently, the RPM and DNF databases are located in /var. Let's move them to /usr.

Owner

• Name: Chris Murphy
• Email: chrismurphy@fedoraproject.org

Current status

• Targeted release: Fedora Linux 36
• Last updated: 2021-12-06
• FESCo issue: <will be assigned by the Wrangler>
• Tracker bug: <will be assigned by the Wrangler>
• Release notes tracker: <will be assigned by the Wrangler>

Detailed Description

Current location

/var/lib/rpm 
/var/lib/dnf

New location

/usr/lib/sysimage/rpm 
/usr/lib/sysimage/dnf

Benefit to Fedora

• The RPM and DNF databases describe the state of (primarily) /usr. Storing these databases in /usr will more easily facilitate OS rollback, without affecting /var.

• Helps align Fedora variants with each other
  • rpm-ostree based systems (including CoreOS, IoT, Silverblue, Kinoite) already use /usr/lib/sysimage for rpmdb.

• Consistency with another RPM-based distro, (open)SUSE has made this change

Scope

• Proposal owners:

• Other developers:
  • changes in rpm and dnf-data packages
    • create the new path instead of old
    • create symlinks for the old path to new path
  • changes in SElinux policy

• Release engineering: #Releng issue 10441
• Policies and guidelines: N/A (not needed for this Change)

• Trademark approval: N/A (not needed for this Change)

• Alignment with Objectives:

Upgrade/compatibility impact

Change will be applied on upgrades to Fedora 36.

How To Test

• Clean install or upgrade an existing Fedora system
• Note the changed database paths (new location) and symlinks in the old location
• Check that rpm and dnf commands work as expected, e.g.

dnf history  
rpm -qa

User Experience

Users will notice:

• symlinks in the old locations for the databases, pointing to the new locations;
• paths existing in the new locations.

Otherwise, the change should be invisible to users.

Dependencies

• rpm-ostree probably should make /usr/share/rpm a symlink to /usr/lib/sysimage/rpm rather than the reverse, as it is currently.

Contingency Plan

• Contingency mechanism: Revert the change, try again the next Fedora release.
• Contingency deadline: Beta freeze
• Blocks release? Yes