Moving from strict to classic confinement

[Eloy García (PC Actual)]

Hello everybody.

I currently have a snap package published on the store. It is called
wallpaperdownloader and it is a Java-based application. So far, it has been
packaged using the strict confinement. The application basically downloads
wallpapers from the Internet and sets the wallpaper when the user requests
it. Because there are a lot of desktop environments, I have ended up using
a lot of Linux commands from the java application in order to achieve these
goals. For some DE there is no problem at all: for example, using gsettings
interface, GNOME Shell and Unity change the background flawlessly. MATE is
working properly too (I had to include mate-desktop-common as stage
package) but XFCE and KDE... no way. In addition, some of the most simple
features (open a file explorer for example) don't work.

I have been testing the classic confinement and all these features work! In
addition, I don't need to include some dependencies like desktop-gtk3 or
use a shell script wrapper to launch the application. Then, I'm considering
to move my snap package from stric to classic confinement but i don't know
the possible implications:

1.- Are the interfaces still needed when using classic confinement?
2.- From the user point of view: if wallpaperdownloader is already
installed and I change the confinement, when snapd upgrades it, will it
work flawlessly? I mean, the upgrade process will be automatic or it will
require manual intervention from the user?
3.- As I see classic confinement, it is a feature to make snap packages
more easily but they only will work on a "classic" Ubuntu system. If Ubuntu
is finally migrated to a Snappy system, I guess classic confinement won't
work and all these packages should be migrated to strict confinement again,
am I right?

Thank you all for your time :)

Best,

Eloy
-- 
Eloy García Almadén