Latest revision as of 19:58, 18 January 2022

Relocate RPM database to /usr

Summary

Currently, the RPM databases is located in /var. Let's move it to /usr. The move is already under way in rpm-ostree-based installations, and in (open)SUSE.

Owner

Name: Chris Murphy, Michel Alexandre Salim, Neal Gompa
Email: bugzilla@colorremedies.com, michel@michel-slm.name, ngompa13@gmail.com

Current status

Targeted release: Fedora Linux 36
Last updated: 2022-01-18
devel thread
FESCo issue: #2731
Tracker bug: #2042099
Release notes tracker: #791

Detailed Description

Current location

/var/lib/rpm

New location

/usr/lib/sysimage/rpm

/var/lib/rpm will be a symlink pointing to /usr/lib/sysimage/rpm

The RPM database primarily describes the state of /usr. Storing the databases in /usr will more easily facilitate OS snapshots and rollback, without affecting /var.
The need for moving rpmdb to /usr was brought up in a 2017 thread on the upstream rpm-maint@ list. Various locations for rpmdb (and similar databases) is discussed in the thread, with the end result being /usr/lib/sysimage/rpm.
There's upstream RPM, rpm-ostree, and (open)SUSE agreement for this location.

Note: Changing the file system layout to accommodate a snapshot+rollback regime is implied, but not required by this proposal. For example, Fedora has long placed /home on a separate subvolume (or file system) so it can be isolated from system root. Likewise, it makes sense to isolate /var/log and possibly /var/lib/libvirt/images so these locations continue to carry forward in time, even if the system root does a rollback.

Feedback

There will be no change to DNF as part of this change proposal. DNF's history will remain in /var until DNF 5. Discussion continues about the effect of a snapshot+rollback regime on DNF history. Relocate DNF history to /usr.

Upstream RPM accepts the change, but institutionally don't like the loss or weakening of a very well known location for the database, and anticipate complaints.

Benefit to Fedora

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 have made this change.
Accounts for various snapshot+rollback regimes, i.e. it's a beneficial change whether Btrfs or device-mapper based.
Is a preparatory step to support boot-to-snapshot and transactional update methods for dealing with problematic updates and upgrades.

Scope

Proposal owners:
- changes in rpm package
  - create the new path
  - create a symlink for the old path pointing to new path
Other developers:
- changes in SElinux policy
- tracking bug for supermin: test if a package has been installed/updated/removed so that we can rebuild our cache
- tracking bug for libguestfs: build a "phony" Fedora image for testing with a fake RPM database
- possible bug in DNF when doing dnf list which writes to one or more rpmdb files (these might be file metadata changes not file data changes)

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 to offline upgrades, similar to the RPM sqlite database change. A systemd service will move the rpmdb from /var to /usr, then create a symlink pointing to /usr from /var.

Create /usr/lib/sysimage/rpm (rpm package will do this at preinst)
Create symlinks in /usr/lib/sysimage/rpm/ pointing to files in /var/lib/rpm/ (rpm package will do this at preinst)
Change the dbpath in /usr/lib/rpm/macros to /usr/lib/sysimage/rpm (rpm package will be patched to do this on F36+)
Request rpm rebuild the database (done via systemd service)
Remove /var/lib/rpm and create a symlink /var/lib/rpm -> /usr/lib/sysimage/rpm (done via systemd service)

How To Test

Perform a new clean install, or upgrade a system
Check that /var/lib/rpm is a symlink to /usr/lib/sysimage/rpm
Check that /usr/lib/sysimage/rpm is populated with at least rpmdb.sqlite, possibly also rpmdb.sqlite-shm and rpmdb.sqlite-wal
Confirm rpm -q <package> and/or rpm -qa still work

User Experience

symlink /var/lib/rpm -> /usr/lib/sysimage/rpm

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.
PackageKit might use inotify on /var/lib/rpm need to check if it does and whether it should be changed or add the additional path

Contingency Plan

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

Documentation

Release Notes

@@ Line 6: / Line 6: @@
 == Owner ==
-<!--
-For change proposals to qualify as self-contained, owners of all affected packages need to be included here. Alternatively, a SIG can be listed as an owner if it owns all affected packages.
+* Name: [[User:chrismurphy| Chris Murphy]], [[User:Salimma|Michel Alexandre Salim]], [[User:Ngompa|Neal Gompa]]
-This should link to your home wiki page so we know who you are.
+* Email: bugzilla@colorremedies.com, michel@michel-slm.name, ngompa13@gmail.com
--->
-* Name: [[User:chrismurphy| Chris Murphy]]
-<!-- 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: chrismurphy@fedoraproject.org
-* Name: [[User:Salimma|Michel Alexandre Salim]]
-* Email: salimma@fedoraproject.org
 <!--- UNCOMMENT only for Changes with assigned Shepherd (by FESCo)
 * FESCo shepherd: [[User:FASAccountName| Shehperd name]] <email address>
 -->
 == Current status ==
-[[Category:ChangePageIncomplete]]
+[[Category:ChangeAcceptedF36]]
-<!-- When your change proposal page is completed and ready for review and announcement -->
-<!-- remove Category:ChangePageIncomplete and change it to Category:ChangeReadyForWrangler -->
-<!-- The Wrangler announces the Change to the devel-announce list and changes the category to Category:ChangeAnnounced (no action required) -->
-<!-- After review, the Wrangler will move your page to Category:ChangeReadyForFesco... if it still needs more work it will move back to Category:ChangePageIncomplete-->
-<!-- Select proper category, default is Self Contained Change -->
-<!-- [[Category:SelfContainedChange]] -->
 [[Category:SystemWideChange]]
@@ Line 39: / Line 25: @@
 ON_QA -> change is fully code complete
 -->
-* FESCo issue: <will be assigned by the Wrangler>
+* [https://lists.fedoraproject.org/archives/list/devel@lists.fedoraproject.org/thread/G6LFNGOXZXFWZM3IWT6MLZWGMNSIZCWM/ devel thread]
-* Tracker bug: <will be assigned by the Wrangler>
+* FESCo issue: [https://pagure.io/fesco/issue/2731 #2731]
-* Release notes tracker: <will be assigned by the Wrangler>
+* Tracker bug: [https://bugzilla.redhat.com/show_bug.cgi?id=2042099 #2042099]
+* Release notes tracker: [https://pagure.io/fedora-docs/release-notes/issue/791 #791]
 == Detailed Description ==
@@ Line 50: / Line 37: @@
 <pre>/usr/lib/sysimage/rpm</pre>
-The proposal is to apply the new location only to new clean installs only. It will not apply to upgrades.
+<code>/var/lib/rpm</code> will be a symlink pointing to <code>/usr/lib/sysimage/rpm</code>
+* The RPM database primarily describes the state of `/usr`. Storing the databases in `/usr` will more easily facilitate OS snapshots and rollback, without affecting `/var`.
+* The need for moving rpmdb to /usr was brought up in a [http://lists.rpm.org/pipermail/rpm-maint/2017-October/006681.html 2017 thread] on the upstream rpm-maint@ list. Various locations for rpmdb (and similar databases) is discussed in the thread, with the end result being `/usr/lib/sysimage/rpm`.
+* There's upstream RPM, rpm-ostree, and (open)SUSE agreement for this location.
-<code>/var/lib/rpm</code> will be a symlink pointing to <code>/usr/lib/sysimage/rpm</code>
-Changing the file system layout to accommodate a snapshot+rollback regime is implied, but not required by this proposal. For example, Fedora has long placed `/home` on a separate subvolume (or file system) so it can be isolated from system root. Likewise, it makes sense to isolate `/var/log` and possibly `/var/lib/libvirt/images` so these locations continue to carry forward in time, even if the system root does a rollback.
+Note: Changing the file system layout to accommodate a snapshot+rollback regime is implied, but not required by this proposal. For example, Fedora has long placed `/home` on a separate subvolume (or file system) so it can be isolated from system root. Likewise, it makes sense to isolate `/var/log` and possibly `/var/lib/libvirt/images` so these locations continue to carry forward in time, even if the system root does a rollback.
 == Feedback ==
@@ Line 60: / Line 51: @@
 There will be no change to DNF as part of this change proposal. DNF's history will remain in `/var` until DNF 5. Discussion continues about the effect of a snapshot+rollback regime on DNF history. [http://lists.rpm.org/pipermail/rpm-ecosystem/2021-December/000769.html Relocate DNF history to /usr.]
-Upstream RPM accept the change, but institutionally don't like the loss or weakening of a [http://lists.rpm.org/pipermail/rpm-ecosystem/2021-December/000781.html very well known location] for the database, and [http://lists.rpm.org/pipermail/rpm-ecosystem/2021-December/000781.html anticipate complaints].
+Upstream RPM accepts the change, but institutionally don't like the loss or weakening of a [http://lists.rpm.org/pipermail/rpm-ecosystem/2021-December/000781.html very well known location] for the database, and [http://lists.rpm.org/pipermail/rpm-ecosystem/2021-December/000781.html anticipate complaints].
 == Benefit to Fedora ==
-* The RPM database primarily describes the state of `/usr`. Storing the 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 have made this change.
+* Accounts for various snapshot+rollback regimes, i.e. it's a beneficial change whether Btrfs or device-mapper based.
+* Is a preparatory step to support boot-to-snapshot and transactional update methods for dealing with problematic updates and upgrades.
-* Consistency with another RPM-based distro, (open)SUSE has made this change
-* Accounts for various snapshot+rollback regimes, i.e. it's a beneficial change whether Btrfs or device-mapper based regimes.
 == Scope ==
@@ Line 79: / Line 68: @@
 *** create the new path
 *** create a symlink for the old path pointing to new path
-<!-- What work do the feature owners have to accomplish to complete the feature in time for release?  Is it a large change affecting many parts of the distribution or is it a very isolated change? What are those changes?-->
+* Other developers:
+** changes in SElinux policy
+** tracking bug for supermin: test if a package has been installed/updated/removed so that we can rebuild our cache
+** tracking bug for libguestfs: build a "phony" Fedora image for testing with a fake RPM database
+** possible bug in DNF when doing `dnf list` which writes to one or more rpmdb files (these might be file metadata changes not file data changes)
-* Other developers: <!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
-<!-- What work do other developers have to accomplish to complete the feature in time for release?  Is it a large change affecting many parts of the distribution or is it a very isolated change? What are those changes?-->
-** changes in SElinux policy
 * Release engineering: [https://pagure.io/releng/issue/10441 #Releng issue 10441]
-* Policies and guidelines: N/A (not needed for this Change) <!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
+* Policies and guidelines: N/A (not needed for this Change)
-<!-- Do the packaging guidelines or other documents need to be updated for this feature?  If so, does it need to happen before or after the implementation is done?  If a FPC ticket exists, add a link here. Please submit a pull request with the proposed changes before submitting your Change proposal. -->
 * Trademark approval: N/A (not needed for this Change)
-<!-- If your Change may require trademark approval (for example, if it is a new Spin), file a ticket ( https://pagure.io/Fedora-Council/tickets/issues ) requesting trademark approval from the Fedora Council. This approval will be done via the Council's consensus-based process. -->
+* Alignment with Objectives:
-* Alignment with Objectives:
 == Upgrade/compatibility impact ==
 <!-- What happens to systems that have had a previous versions of Fedora installed and are updated to the version containing this change? Will anything require manual configuration or data migration? Will any existing functionality be no longer supported? -->
-Change will not be applied to upgrades.
+Change will be applied to offline upgrades, similar to the RPM sqlite database change. A systemd service will move the rpmdb from /var to /usr, then create a symlink pointing to /usr from /var.
+# Create `/usr/lib/sysimage/rpm` (rpm package will do this at preinst)
+# Create symlinks in `/usr/lib/sysimage/rpm/` pointing to files in `/var/lib/rpm/` (rpm package will do this at preinst)
+# Change the dbpath in `/usr/lib/rpm/macros` to `/usr/lib/sysimage/rpm` (rpm package will be patched to do this on F36+)
+# Request rpm rebuild the database (done via systemd service)
+# Remove `/var/lib/rpm` and create a symlink `/var/lib/rpm` -> `/usr/lib/sysimage/rpm` (done via systemd service)
 <!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
 == How To Test ==
-<!-- This does not need to be a full-fledged document. Describe the dimensions of tests that this change implementation is expected to pass when it is done.  If it needs to be tested with different hardware or software configurations, indicate them.  The more specific you can be, the better the community testing can be.
+<!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
+# Perform a new clean install, or upgrade a system
+# Check that `/var/lib/rpm` is a symlink to `/usr/lib/sysimage/rpm`
+# Check that `/usr/lib/sysimage/rpm` is populated with at least `rpmdb.sqlite`, possibly also `rpmdb.sqlite-shm` and `rpmdb.sqlite-wal`
+# Confirm `rpm -q <package>` and/or `rpm -qa` still work
-Remember that you are writing this how to for interested testers to use to check out your change implementation - documenting what you do for testing is OK, but it's much better to document what *I* can do to test your change.
-A good "how to test" should answer these four questions:
-. What special hardware / data / etc. is needed (if any)?
-. How do I prepare my system to test this change? What packages
-need to be installed, config files edited, etc.?
-. What specific actions do I perform to check that the change is
-working like it's supposed to?
-. What are the expected results of those actions?
--->
-* 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.
-<pre>dnf history
-rpm -qa</pre>
-<!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
 == User Experience ==
-<!-- If this change proposal is noticeable by users, how will their experiences change as a result?
- This section partially overlaps with the Benefit to Fedora section above. This section should be primarily about the User Experience, written in a way that does not assume deep technical knowledge. More detailed technical description should be left for the Benefit to Fedora section.
- Describe what Users will see or notice, for example:
+* symlink `/var/lib/rpm` -> `/usr/lib/sysimage/rpm`
-  - Packages are compressed more efficiently, making downloads and upgrades faster by 10%.
-  - Kerberos tickets can be renewed automatically. Users will now have to authenticate less and become more productive. Credential management improvements mean a user can start their work day with a single sign on and not have to pause for reauthentication during their entire day.
- - Libreoffice is one of the most commonly installed applications on Fedora and it is now available by default to help users "hit the ground running".
- - Green has been scientifically proven to be the most relaxing color. The move to a default background color of green with green text will result in Fedora users being the most relaxed users of any operating system.
--->
-Users will notice:
-* symlink in the old locations for the databases, pointing to the new location
 Otherwise, the change should be invisible to users.
@@ Line 154: / Line 122: @@
 <!-- Does finishing this feature block the release, or can we ship with the feature in incomplete state? -->
 * Blocks release? Yes <!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
 == Documentation ==
@@ Line 159: / Line 128: @@
 <!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
 == Release Notes ==

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