build.snapcraft.io uses snapcraft from the deb archive

<sergiusens> cjwatson btw, mind if we work on switching snapcraft to use the snap for lp buidlers?
<cjwatson> sergiusens: I don't mind, but how were you planning to go about it?
<cjwatson> it's a bit involved
<sergiusens> cjwatson oh, then step one would be to get an idea of how involved it is :-)
<sergiusens> I had the impression it would be more about testing that s/apt install snapcraft/snap install snapcraft --classic/ was working as expected on staging
<cjwatson> sergiusens: we need to make it be a switch, not just change it in the code (which is harder to roll back, harder to experiment with on particular snaps, etc.); and probably as part of the same chunk of work we need to add channel control
<cjwatson> sergiusens: which means it needs to be propagated down from the LP buildd-manager, and probably needs data model changes
<sergiusens> cjwatson up to LP or even build.snapcraft.io ?
<sergiusens> I'll write up the proposed set of steps on the forum
<cjwatson> sergiusens: not build.snapcraft.io IMO. We can flip the switch eventually but it needs to be controlled
<cjwatson> sergiusens: IMO the steps are: (1) design data model in LP (possibly taking into account where core is installed from too, at least for the future?) (2) add option to snap build type in launchpad-buildd to cause it to install snapcraft as a snap (3) LP database migration to add whatever new columns we need (4) implement new data model and API changes in LP, and adjust the build args sent to builders (5) possible UI changes
<cjwatson> sergiusens: ordering is important because builders, DB migrations, LP code are all deployed independently so we need to ensure the right kind of compatibility

Sergio, assigning this to you since you said you were planning to work on it. Let us know if that turns out not to be viable.

r13808 in db-stable (http://bazaar.launchpad.net/~launchpad-pqm/launchpad/db-stable/revision/13808) is part of this bug's fix.

2018-03-12 18:49:08,832 INFO 2209-83-1 applied just now in 0.0 seconds

Fixed in stable r18579 <http://bazaar.launchpad.net/~launchpad-pqm/launchpad/stable/revision/18579>.

The initial work here seems OK, but this is only part of the fix; we still need to do more work to present the state in the UI and to roll it out by default.

r18731 in stable (http://bazaar.launchpad.net/~launchpad-pqm/launchpad/stable/revision/18731) is part of this bug's fix.

Fixed in stable r18766 <http://bazaar.launchpad.net/~launchpad-pqm/launchpad/stable/revision/18766>.

This is now code-complete in Launchpad: we have the ability to make this change globally. I'm not yet doing so because we'd like to have some kind of QA of the set of snaps that Launchpad builds (or at least a reasonable sample) to make sure that we aren't wildly regressing them by switching to the snap.

This has been done for a while except for the legacy case of snaps that don't specify any base at all. I think we might as well close this bug.