docs: [FC-0002] plugin extensions ADR

docs/decisions/0006-plugin-extensions.rst

@@ -0,0 +1,59 @@
+Django App Plugin extensions
+============================
+
+Status
+------
+
+Proposed
+
+
+Context
+-------
+
+More functionality is planned to be added to the Credentials service as a part of
+`credentials/issues/1734`_ and `credentials/issues/1736`_.
+Credentials may benefit from adoption of the `Django App Plugin`_ functionality.
+It would provide additional possibilities to support many integrations with third-party
+services for credentials sharing, like digital credentials platforms, digital wallets,
+credentials signing services, etc.
+
+For more information on plugins in particular, see the `Django Apps Plugin README`_.
+
+.. _`credentials/issues/1734`: https://github.com/openedx/credentials/issues/1734 
+.. _`credentials/issues/1736`: https://github.com/openedx/credentials/issues/1736 
+.. _Django App Plugin: https://github.com/openedx/edx-django-utils/blob/master/edx_django_utils/plugins/README.rst
+.. _Django Apps Plugin README: https://github.com/openedx/edx-django-utils/blob/master/edx_django_utils/plugins/README.rst
+
+
+Decision
+--------
+
+* Implement improved plugin support of Django apps in the Credentials service by adopting `edx_django_utils`_ module. Django apps plugins will support `overrides system`_ for core functionality.
+
+* Use plugin applications for future extension points and optional functionality for the Credentials service.
+
+.. _edx_django_utils: https://github.com/openedx/edx-django-utils
+.. _overrides system: https://github.com/openedx/edx-django-utils/blob/master/edx_django_utils/plugins/pluggable_override.py#L11
+
+Consequences
+------------
+
+* It will be easier to extend the Credentials service and implement new business cases without building a monolithic unit.
+
+* It will be possible to override the core functionality of the Credentials service for specific use cases without direct code modifications.
+
+* It will become easier to support Credentials system "upgradability".
+
+* It may introduce complexity for code discovery in case of implicit overrides and a lack of documentation on particular plugin functionality.
+
+Rejected Alternatives
+---------------------
+
+* Adding Django applications directly to credentials/apps.
+
+References
+----------
+
+The Open edX platform Django apps ADR 0014: https://github.com/openedx/edx-platform/blob/master/docs/decisions/0014-no-new-apps.rst
+
+How to enable plugins for an IDA: https://github.com/openedx/edx-django-utils/blob/master/edx_django_utils/plugins/docs/how_tos/how_to_enable_plugins_for_an_ida.rst