oharsta
commented
3 years ago What you are looking for is described here: https://docs.spring.io/spring-security-saml/docs/current/reference/html/configuration-sso.html#configuration-sso-process-idp-init
You do not need the SP XML metadata at the IdP for that, only the ACS of the SP.
In the current setup the SP knows about the IdP, but the IdP does not know about the SP. The assertion is send back to the ACS location in the authnRequest. If you want the IdP to know about the SP (why?) then you would have to implement that.