Switch from Livepatch service to UA client

[Robert Ancell]

software-properties currently uses a HTTP over Unix domain socket service from the livepatch snap to get the status and enable/disable it. This service is being deprecated with the 'ua' command line tool now providing this functionality. software-properties also installed the snap to gain access to this service. This is no longer required as the 'ua' tool does this.

(*) The Livepatch service is a HTTP over Unix domain service running on livepatchd.sock inside the livepatch snap.

[Robert Ancell (robert-ancell)]

The current implementation shows "Last check for updates". As far as I can tell this information is not available via the UA client. It also shows a list of applied CVE fixes, which again I don't think is available from the UA client.

See attached screenshot of current implementation in 18.04 LTS.

[Sebastien Bacher (seb128)]

After discussing that a bit it sounds like we only want to replace the use of the livepatch auth service and enable livepatch using UA, we can keep using the socket to get the other informations

[Sebastien Bacher (seb128)]

it's not going to be ready for impish

[Ken VanDine (ken-vandine)]

@robert-ancell: IIRC you had some code for this already? Or am I misremembering it?

[Robert Ancell (robert-ancell)]

I had a WIP branch done as part of the ESM work. That's now been rescheduled to April 2022, and the Livepatch migration will be done as part of that.