[snaps] License information from the store not available

Maybe related: https://bugs.launchpad.net/ubuntu/+source/gnome-software/+bug/1552200

snapd is not providing any license information, see bug 1555569 for an example of what information we get.

I can confirm snappy receives the license information from the store, and promptly forgets about it.

Ooops.

I had an attempt at solving this in snapd with the attached patch. This passes through the "license" field from the store [1] and can make a search in gnome-software show this license field.

However, this field doesn't exist for installed snaps. This is because the snap metadata doesn't contain this field and instead contains differently defined license fields [2] (it refers to a license file, not a string).

This needs some design input to progress. It seems to me that one of the following needs to occur:

- The license file that is referred in the snap YAML would have to be copied into the store database. This file could then be accessed either from the store or from a locally installed snap. This has the downsides that common license (e.g. GPL) are hard to match (requires checking the whole license file) and extra data would need to be downloaded (as opposed to a short string).

- The snap YAML would gain the license field as used in the store. The existing license file could remain for non-common / complex licenses. The downside of this is that existing snaps might have a license set in the store but not in the .snap file (searching in gnome-software would show a license but after install it would not).

[1] http://search.apps.ubuntu.com/docs/#package
[2] http://snapcraft.io/docs/build-snaps/syntax

Hey Robert, any progress here?

Harald's post became popular today: https://apachelog.wordpress.com/2017/01/30/kde-applications-in-ubuntu-snap-store/

Sadly, it has a prominent picture of this bug too :)

I'm not working on this patch, it really needs input from the Snappy/Store architects as to how they want this to work.

SRUing a fix to remove license warning and just say "Unknown" in bug 1662750.

Mailing list discussion about using SPDX license tags:
https://lists.ubuntu.com/archives/snapcraft/2017-January/002774.html

The above link is wrong, should be:
https://lists.ubuntu.com/archives/snapcraft/2017-January/002746.html

Forum topic:
https://forum.snapcraft.io/t/snap-license-metadata

Ubuntu 19.04

Gnome-calculator (GPL-3.0+) and kbrunch (GPL-2.0+) from the snap Store show their license as 'Free'. The bug mentioned in #1 is marked as fix released.

I'm going to be bold and go ahead and mark this bug as fix released.