SP doesn't support logout.
I have set up a SP according to docs/example, and I have issue with logout.
Basically, I get a traceback caused by discrepancy between logout call and corresponding function definition.
The failure looks legit.
You are correct, full SAML log out is not implemented yet. Currently, flask-saml2 can log you out of the SP by deleting the auth details stored in the session, then redirect you to the IdP's logout page which can also log you out by clearing the session. SAML Single Logout (SLO) is not implemented yet, from either the SP or IdP sides.
Is there an implementation approach you'd support around SLO? I imagine it would require some manner of shared storage that the sp.get_auth_data_in_session would have to check in with on every request, so that the session could be invalidated by the SLO endpoint?