Layer licensing and charm licensing

[Antonio Rosales]

On Thu, May 5, 2016 at 9:47 AM, Mark Shuttleworth <mark at ubuntu.com> wrote:
> Hi folks
>
> The move to layers, which is fantastic from a charming productivity point of
> view, will also raise the question of licensing in a cross-charm way.
> Originally, we envisaged each charm being licensed by the charmer
> independently, but layers introduce cross-cutting licensing questions, and
> in particular, questions about copyleft.

Thanks for kicking off this thread.

>
> It certainly is not our intent that contributions from Canonical (which we
> generally prefer to make under copyleft licenses) should force a charm
> author to pick a copyleft license for their own contributions to their own
> charm.
>
> There are two options for common code that would be obvious solutions - a
> limited copyleft (LGPL) and a permissive (Apache2 or BSD). Both options
> enable people to bring shared public layers into their charms but still pick
> their own licenses for their own layers and additional bits. The LGPL option
> would require people modifying shared layers to allow others to use their
> modifications ("if you edit this file, we can merge your edits") but any new
> pieces created by them (typically specific to their charms) could be
> restricted for their own use.
>
> The OSM project, which is using charms for telco application modelling, has
> a preference for Apache2, which is arguably also a preference for many other
> industrial-scale initiatives.

It will be interesting to hear people's opinion on the subject. In my
experience upstreams are more comfortable to contribute, include, and
build on-top of charms that have an Apache License. Thus, as a lowest
common denominator perhaps Apache encourages more comfort for building
on top of and/or reusing.

-thanks,
Antonio

>
> We could also dual-license these components (Apache2 + LGPL, or even Apache2
> + GPL).
>
> Am writing to gather feedback from the charmer community as to your
> preferences in this regard.
>
> Mark