RFC application factories approach

[lnielsen]

Currently we have the following environments where we need a Flask application running:

• Celery
• WSGI
• CLI

For all of them we currently create two Flask application factories:

• UI app (create_app)
• API app (UI app creates it and adds it to /api)

Many core Flask Extensions are initialised twice - once on the UI app and once on the API app. The problem with this approach is in all scenarios we create two Flask applications even if we don't need them. E.g. the Celery application only needs one Flask application. Also the CLI shell command and many other commands would need just one Application. The CLI run command will however need the full WSGI application (i.e. the two apps) to run.

It seems to me that our current approach is not ideal, but however also don't have any other ideal solutions.