F23 System Wide Change: DNF System Upgrades

= Proposed System Wide Change: DNF System Upgrades = https://fedoraproject.org/wiki/Changes/DNF_System_Upgrades Change owner(s): * Will Woods (fedup author) * Zbigniew Jędrzejewski-Szmek (systemd developer) * Radek Holy (DNF developer) == Detailed Description == While fedup worked well in many circumstances, there were a lot of problems resulting from using upgrade.img. This has caused nasty, hard-to-debug blocker bugs for every release since it was introduced. It turns out that upgrade.img was relying on some undocumented, unsupported systemd behavior. After F22 this was discussed on the systemd-devel mailing list, and the conclusion was that fedup's boot behavior is broken by design, and systemd can't (and won't) continue to support it. systemd already supports a simpler, more reliable method for performing Offline System Updates; the systemd team suggests using that to perform system upgrades. Most of the remaining problems with fedup were caused by the fact that it was separate from the system packaging tools, and therefore had slight (and confusing) differences from the normal package update mechanisms. Therefore, we propose that system upgrades should be handled by the system packaging tools, using systemd's Offline System Updates facility. dnf-plugin-fedup is a proof-of-concept implementation; we propose to integrate support for this into DNF itself. == Scope == Proposal owners: Make DNF able to send progress output to Plymouth (basically done; see dnf #281 and #313) Modify Offline System Updates spec as needed to support major system upgrades (in progress, see this systemd-devel thread) Support Offline System Updates in DNF (dnf-plugin-fedup does this, but it could be integrated into DNF itself) Add plugin to dnf-plugins-core or dnf Write man pages and other documentation Obsolete and retire fedup Other developers: Fix any conflicts with packagekit-offline-update.service In the unlikely event that some kind of offline system migration is necessary (like UsrMove), it should be handled the same way as UsrMove - i.e. by a dracut script that runs the first time the new system boots after the upgrade. Release engineering: Drop upgrade.img from image builds Policies and guidelines: FedUp, Upgrading, and other documentation will need changes