Code review comment for lp:~sergiusens/ubuntu-touch-session/install_clicks

> I guess there are a number of different use cases:
> a) package is in app store but we want to preinstall it
> b) package is not in app store but we want to preinstall it
>
> and another subcase:
> 1) package may be removed by end-user
> 2) package may not be removed by end-user
>
> and what we want to decide is whether we're upgrading/reinstalling packages
> and whether we do this on every boot.
>
>
> Now some conclusions:
> - it seems clear to me that for a), it doesn't matter whether we update it or
> not as updates can be delivered from appstore, so we could optionally skip
> this on boot
> - it seems natural that things that are in appstore and hence can be installed
> after the fact should be uninstallable, so that a) should imply 1)
> - it is obvious that in the case of b), we must update it on each boot
> - it seems natural that in the case of b), we should not allow removal --
> otherwise lets just put it in the appstore
>
> So what I'd propose is followings:
> * /usr/share/preinstalled/click and /custom/preinstalled/click contain clicks
> that aren't in the appstore and must be installed or upgraded automatically
> and can't be removed (no flag to allow this for now, but should add one)
> * /opt/click.u.c is prepopulated in the rootfs with appstore packages that we
> want to install by default but may remove, but is never upgraded (which I
> think is what happens with writable pathes?)

Makes sense. Let's do this.

I will add one more thing which is to check the image upgrade version (as discussed with rsalveti) so we can only run this on first boot after an upgrade.

> We should add a flag for packages that can't be removed (both for appstore and
> preinstalled packages).

Yes, this would allow for doing the only run the package install on upgrade