Allow building livefses against a view of the archive at a fixed point in time

Bug #1765933 reported by Colin Watson on 2018-04-21
10
This bug affects 2 people
Affects Status Importance Assigned to Milestone
Launchpad itself
High
Colin Watson
livecd-rootfs (Ubuntu)
Undecided
Unassigned

Bug Description

It would be useful to be able to dispatch a set of livefs builds that all reliably build from the same point in time in the archive's history, even if they're dispatched at slightly different times. We did the InRelease-by-hash work (https://bugs.debian.org/886745, and subsequent Launchpad publisher changes) as a prerequisite for this. We're now ready to consider the next stage. I believe that there are three major chunks of work here:

1) Somebody needs to work out the livecd-rootfs/live-build bits, which I think ought to be a Foundations job (I don't expect to do this part myself). It needs to pick up the inrelease-path option from the sources.list in the environment where livecd-rootfs is run and propagate that through while building the image, but make sure that the inrelease-path option *doesn't* end up in the sources.list in the final image (just like the way we build from ftpmaster.internal but don't actually leave that in the final image, since it wouldn't work).

2) In parallel with 1), we need to improve Launchpad's internal tracking of the history of archive index files. At the moment, the only feasible interface we could offer would be that the entity scheduling livefs builds would need to work out the SHA-256 hashes of all the relevant InRelease files and tell Launchpad what to use. This is cumbersome and hard to automate. Instead, it would be much better to make it work by timestamp (perhaps even simply having an option to pick whatever's current when the builds are scheduled), but to do that we need to convert ArchiveFile into a history table, adding date_created and date_superseded columns so that we can work out which version was live at any given time.

3) Once both 1) and 2) are done, we can add the relevant options to Launchpad's livefs build code to cause the correct sources.list to be dispatched.

Related branches

Colin Watson (cjwatson) on 2018-04-21
Changed in launchpad:
status: Triaged → In Progress
assignee: nobody → Colin Watson (cjwatson)
Launchpad Janitor (janitor) wrote :

Status changed to 'Confirmed' because the bug affects multiple users.

Changed in livecd-rootfs (Ubuntu):
status: New → Confirmed
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