[SRU] updates to the maas deb2snap package

[Alberto Donato]

The current (1:0.6) maas packages in focal provide transition to the MAAS snap.

This is currently done by getting maas from "stable/ubuntu-$release" for the default branch (which is currently 2.7).
We want to change this to ensure a consistent behavior, always installing 2.7 even once a new release becomes the default track.

The attached MP implement this, along with a few fixes/cleanups for the current preinst logic.
Specifically, the current package doesn't handle an upgrade from a previous version of the transitional package.

[Impact]
* upgrading to focal currently migrates to the stable/ubuntu-20.04 snap, which is currently 2.7 but will be 2.8 in the future

[Testcase]
* Install maas on bionic (either from archive or ppa:maas/2.6)
* Upgrade to focal.
* `snap info maas` shows snap installed from `2.7/stable/ubuntu-20.04`

[Regression potential]
* Regression potential is low, aside from the desired change in behavior selecting snap channel the branch prvoides a fix for the case of upgrading the transitional package to a newer version.

[Steve Langasek (vorlon)]

Hello Alberto, or anyone else affected,

Accepted maas into focal-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/maas/1:0.7 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed 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 https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . 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.

[Alberto Donato (ack)]

Hi Steve,

thanks for uploading the package.

I ran the following test scenarios, confirmed upgrade logic worked in both cases:

1)
- clean bionic install
- install maas 2.6 from ppa:maas/2.6
- install 1:0.7 packages
- the snap gets installed from "2.7/stable/ubuntu-20.04"

2)
- clean focal install
- enabled focal-proposed
- install "maas"
- the snap gets installed from "2.7/stable/ubuntu-20.04"

[Chris Halse Rogers (raof)]

Does this need to be fixed in groovy before I release the SRU to focal-updates?

[Alberto Donato (ack)]

@raof, no maas has been removed from the archive in Groovy

[Launchpad Janitor (janitor)]

This bug was fixed in the package maas - 1:0.7

---------------
maas (1:0.7) focal; urgency=medium

  * When a track is not specified, default to 2.7/stable. If MAAS deb
    version is higher than 2.7, pick the same track. LP: #1878769
  * Fix issue where "MAAS not currently set up" notice shows even when the
    snap is configured.
  * No-op when upgrading from a transitional deb, as migration already
    happened.
  * Rename "get_snap_mode" to "snap_mode".
  * Rename DEFAULT_SNAP_* variables to align with snap terminology.

 -- Alberto Donato <email address hidden> Wed, 06 May 2020 13:48:50 +0200

[Łukasz Zemczak (sil2100)]

The verification of the Stable Release Update for maas 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.