snap upgrade to 2.14.2~16.04 in xenial lxc hangs

[Greg Lutostanski]

Ran into this with deploying a juju charm to a local lxd controller.

Recreates with:
https://paste.ubuntu.com/23147333/

Related bugs:
 * bug 1576692: fully support package installation in systemd

[Scott Moser (smoser)]

This is likely a duplicate of bug 1576692, simply different fallout of being unable to run package installation "during boot".

[Launchpad Janitor (janitor)]

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

[Marco Ceppi (marcoceppi)]

A work around for Juju deployments: http://paste.ubuntu.com/23147632/

[Scott Moser (smoser)]

This can also be worked around specifically for this snapd update by a hold on snapd package.

#cloud-config
#
# package_upgrade true means to upgrade packages in the image causes
# upgrade of snapd (bug 1621229). upgrade of snapd triggers bug 1576692.
# http://pad.lv/1621229
# http://pad.lv/1576692
#
# holding snapd via the bootcmd below means the upgrade does not
# install a new snapd, and thus it works as desired.
package_upgrade: true
bootcmd:
  - "echo snapd hold | dpkg --set-selections"

[Martin Pitt (pitti)]

I reported the same with a detailled analysis in bug 1621336, so maarking this a dupe.