Re: App image experiments

[Colin Walters <walters verbum org>]

Ok, so it's getting a little boring to be making a potential OS but not
have an application installation mechanism =)  I've been thinking about
this, and in particular what
https://docs.google.com/document/d/1QTgxakyUVFMkvr-xFY2Xg9lYjcJLd6kPTl3Ij5_dL7Q/edit
calls the "Search Path Problem".

New mechanisms to download application blobs aren't super interesting
until we attempt to address this.

The core issue is we don't want to toss out centralized management.
Concretely for example, an admin should be able to get a unified view of
all of the gsettings schemas, for the system and for each app.

But here's what's making my head spin a bit - assuming we have per-user
application installation (and we should), does the system support having
an admin construct the schema search path just for that user?  Like:

# whoami
root
# gsettings list-recursively --for-user=walters
... 

?  Or would we just say that in order to get a view of the environment
for user walters, you just log in via e.g. "runuser walters", and run
gsettings there?  The downside of that is - how would you do mandatory
controls on a per-user installed application?  You'd be putting a key
into /etc/dconf that the system dconf is unaware of.  Maybe it won't
complain...

And here's an additional level of complexity - say we want to do
something Android-like and isolate applications from each other.  Then
the system will need to be able to construct the Search Path for pairs
of (Application, User), as well as the merged view of all applications
for a given User.

Other projects trying to move forward in this area just have per-user
Search Paths, effectively set on login.  That's not too terrible as long
as the parts that need to be live monitored are.  This is really what
the XDG basedir allows now.   

Anyways; it's kind of tempting to just set up a builder that drops out
zip files or something that unpack per-user into ~/.local to at least
have *something*...