Autoupdate
Autoupdate is a feature that will guarantee you are always up to
date. It is enabled by default, and can be disabled via snappy config.
Usage
To check whether the feature is active, run
snappy config ubuntu-core | grep autoupdate
If you want to disable it run
echo 'config: {ubuntu-core: {autoupdate: off}}' | sudo snappy config ubuntu-core -
and you then re-enable it via
echo 'config: {ubuntu-core: {autoupdate: on}}' | sudo snappy config ubuntu-core -
Every time autoupdate triggers it will try to update the whole system;
if an ubuntu-core update is available the system will automatically
reboot, although a message is printed to console with instructions on
how to abort the reboot, in case you are logged in at the time.
If you need a single configuration that works both on 15.04 and rolling, you can use both the old and new keys, e.g.
config: {ubuntu-core: {autoupdate: on, autopilot: on}}.
Implementation details
Autoupdate used to be called autopilot (but that got very confusing,
especially when people were using snappy with other things that have
their own autopilot, like an OpenStack deployment that used
Canonical's own OpenStack Autopilot, or in mobile robots that could
fly themselves); the systemd units still use this name.
For more details of when it is to be triggered you could dig into the implementation, via
systemctl list-timers snapd.refresh.timer
To check whether the update ran, run
systemctl status -l snapd.refresh.service
and to view any output from the command run
sudo journalctl -u snapd.refresh.service