August-W: Made ServiceProvider more configurable without needing to extend it

[August-W]

Added class variables in ServiceProvider for logout_endpoint, login_return_endpoint, entity_id, and acs_redirect_endpoint, and added parameters in the create_blueprint method.
With acs_redirect_endpoint, you can explicitly set the relay_state in AssertionConsumer, for cases in which the SAML Request does not contain a relay_state parameter.
Now, if you don't want to use a url to the saml xml file as your entity_id (default behaviour), you can set the entity_id in ServiceProvider.

Fixed an issue with the Login class in views.py. It now supports setting the scheme to "https" (this happens in ServiceProvider's create_blueprint method).

Updated the example sp.py accordingly.

Linked Issues:
#17
#18
#19

[mkilp]

@timheap can we merge this?

[FMJansen]

I’m far from sure about this, but shouldn’t the new entity_id not also be passed as an argument here, same as the scheme? (And then of course also something at line 345)

Suggested change

	def create_blueprint(self, login_endpoint='/login/', login_idp_endpoint='/login/idp/',
	logout_endpoint='/logout/', acs_endpoint='/acs/', sls_endpoint='/sls/',
	metadata_endpoint='/metadata.xml', scheme='http') -> Blueprint:
	def create_blueprint(self, login_endpoint='/login/', login_idp_endpoint='/login/idp/',
	logout_endpoint='/logout/', acs_endpoint='/acs/', sls_endpoint='/sls/',
	metadata_endpoint='/metadata.xml', scheme='http', entity_id=None) -> Blueprint:

[August-W]

I thought about that. The main reason I didn't pass entity_id there is that it seemed to be a little outside the scope of what this create_blueprint function should do. To me, it makes sense to set the scheme together with the various endpoints, as they are related. But you could make a case that even scheme doesn't belong here, as it is setting a value in sp rather than in idp_bp.

I'm open to including entity_id or removing scheme. Maybe creating a separate config_and_create_blueprint function which sets the entity_id and scheme and then calls create_blueprint. Or other ideas? Not sure what the cleanest solution is.

[FMJansen]

Aah, yeah, got it. In that case I’m out of my depth, I wouldn’t know what the cleanest solution would be I’m afraid.

[lucasSzavara]

Is there an update on this? I'm thinking of using this library, but not being able to use https as the scheme is preventing me from using it

[August-W]

Hey @lucasSzavara, I'm not sure if this is getting merged but for now you can just extend ServiceProvider and Login and make the same changes I did here, or you can use my fork

[lucasSzavara]

Thanks @August-W! I'll use your fork, is there anything that I need to change on my code, other than including the scheme parameter?

[August-W]

No problem, @lucasSzavara. You shouldn't have to change anything else. It's been a while since I've looked at this but let me know if you run into any issues.