Support inclusion of snap from specific track/channel/branch

Bug #1882374 reported by Stéphane Graber on 2020-06-06
This bug affects 1 person
Affects Status Importance Assigned to Milestone
livecd-rootfs (Ubuntu)

Bug Description


 * Can only seed snaps from latest track, yet there is desire to support "LTS" tracks.

 * Add support for snap:$SNAP=$TRACK/$RISK/$BRANCH syntax in seeds, e.g.

* snap:lxd=4.0/stable/ubuntu-20.10

[Test Case]

 * Use full-channel specification in the seed and test build ubuntu-server, subproject live build.

[Regression Potential]

 * Backwards compatible with existing seeds.
 * New code only used when full channel is specified in the seed.

[Other Info]

 * Original bug report

We have a bit of a problem right now with LXD in Ubuntu 20.04.

Users upgrading from 18.04 to 20.04 or those installing LXD through the deb shim, will correctly detect that they are on a LTS and auto-select a LTS branch of LXD (defaults to 4.0).

That's however not the case for the images we publish which all default to "latest" and so currently pull in LXD 4.1 and soon 4.2.

This isn't good as the behavior we're aiming for is that LTS users should get an LTS track of LXD (4.0) and non-LTS users should get the latest track.

To fix this, we need to be able to specify a track/channel/branch alongside the snap we want to seed and have livecd-rootfs pull that.

For LXD that would mean "lxd 4.0/stable/ubuntu-20.04" in focal and "lxd latest/stable/ubuntu-20.10" on groovy. The exact syntax doesn't matter and it's probably fair to assume that the ubuntu branch will exist so won't need specifying.

We would like this issue sorted in time for Ubuntu 20.04.1 so we have a good consistent story for those upgrading and those deploying new systems at that time.

Related branches

Steve Langasek (vorlon) on 2020-06-08
Changed in livecd-rootfs (Ubuntu Focal):
milestone: none → ubuntu-20.04.1
importance: Undecided → High
Changed in livecd-rootfs (Ubuntu):
importance: Undecided → High
tags: added: id-5ede6f21cd111d43e8ff3188
Éric St-Jean (esj) on 2020-06-12
Changed in cloud-images:
status: New → Triaged
Launchpad Janitor (janitor) wrote :

This bug was fixed in the package livecd-rootfs - 2.670

livecd-rootfs (2.670) groovy; urgency=medium

  * snap_preseed: support channel specification with snap name (LP: #1882374)

 -- Dimitri John Ledkov <email address hidden> Thu, 09 Jul 2020 18:34:43 +0100

Changed in livecd-rootfs (Ubuntu):
status: New → Fix Released
description: updated
Changed in livecd-rootfs (Ubuntu Focal):
status: New → In Progress

Hello Stéphane, or anyone else affected,

Accepted livecd-rootfs into focal-proposed. The package will build now and be available at in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See for documentation on how to enable and use -proposed. Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested, what testing has been performed on the package and change the tag from verification-needed-focal to verification-done-focal. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-focal. In either case, without details of your testing we will not be able to proceed.

Further information regarding the verification process can be found at . Thank you in advance for helping!

N.B. The updated package will be released to -updates after the bug(s) fixed by this package have been verified and the package has been in -proposed for a minimum of 7 days.

Changed in livecd-rootfs (Ubuntu Focal):
status: In Progress → Fix Committed
tags: added: verification-needed verification-needed-focal
Dimitri John Ledkov (xnox) wrote :

* Stock build done on s390x, no regressions, correct seeding done with backwards compatible stable/ubuntu-20.04.

Dimitri John Ledkov (xnox) wrote :

* Modified build with 4.0/stable/ubuntu-20.04 completed with correct seeding too.

Dimitri John Ledkov (xnox) wrote :

Both builds done against primary archive with livecd-rootfs 2.664.4

tags: added: verification-done verification-done-focal
removed: verification-needed verification-needed-focal
Launchpad Janitor (janitor) wrote :

This bug was fixed in the package livecd-rootfs - 2.664.4

livecd-rootfs (2.664.4) focal; urgency=medium

  * snap_preseed: support channel specification with snap name (LP: #1882374)

 -- Dimitri John Ledkov <email address hidden> Thu, 23 Jul 2020 19:12:10 +0100

Changed in livecd-rootfs (Ubuntu Focal):
status: Fix Committed → Fix Released

The verification of the Stable Release Update for livecd-rootfs has completed successfully and the package is now being released to -updates. Subsequently, the Ubuntu Stable Release Updates Team is being unsubscribed and will not receive messages about this bug report. In the event that you encounter a regression using the package from -updates please report a new bug using ubuntu-bug and tag the bug report regression-update so we can easily find any regressions.

Joshua Powers (powersj) on 2020-10-09
Changed in cloud-images:
status: Triaged → Fix Released
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