[ckan-dev] AGPL as applied to CKAN extensions that interact with external services

[Adam Eijdenberg]

Hi ckan-dev,

We are exploring writing an extension to CKAN that provides an
integration with another system that we host that may allow us to add
some interesting additional features to some of our datasets.

We note that CKAN is licensed under AGPL. As I understand it, the
source for a CKAN extension that is hosted ("conveyed"?) on the same
server as CKAN must also be released under AGPL.

If that extension provides services by interacting with an API on
another server, are there any obligations on the license under which
the source for the component on the other server is offered, if at
all?

Looking around I note the existence of other extensions such as:

- Active Directory authentication for CKAN [0]
- Upload resources to AWS S3 [1]

(and, while not an extension, a dependency by CKAN on Postgresql)

where neither AWS S3, Active Directory, nor Postgresql are licensed
under AGPL, so my assumption is that this kind of usage is both
contemplated and within the spirit of the AGPL, however in attempting
to address this area the AGPL FAQ states [2]:

> If some network client software is released under AGPLv3, does it have
> to be able to provide source to the servers it interacts with?
>
> AGPLv3 requires a program to offer source code to "all users interacting
> with it remotely through a computer network." It doesn't matter if you
> call the program a “client” or a “server,” the question you need to ask
> is whether or not there is a reasonable expectation that a person will
> be interacting with the program remotely over a network.

In this case, I would see the CKAN extension being a network client
(of the API hosted elsewhere) but also being remotely interacted with
in the context of a user interacting with CKAN. As such my first
thoughts are that we would be obligated to release the CKAN extension
under AGPL, but my question remains whether there are any obligations
on source to any APIs provided by other servers that the extension
interacts with as part of its operation?

Many thanks,

Cheers, Adam

[0] http://extensions.ckan.org/extension/adfs/
[1] http://extensions.ckan.org/extension/s3-resources/
[2] https://www.gnu.org/licenses/gpl-faq.html#AGPLv3ServerAsUser