good ruby saml library?

[Jerry Shipman]

Hello,
I know this is not the right place to ask this question, but I thought someone here might know the answer (sorry).

Can anyone recommend a SAML SP library or toolkit for "ruby on rails"?

I am talking to a user who is trying to set up a SAML SP to integrate with our shib IdP. I recommended he use mod_shib with apache, but he thinks it could be the case that he winds up in a hosting environment where he can't just install apache modules (or isn't using apache). 
In such a case, I guess that doing it at the application level (in his ruby on rails) is an option. But I don't know what to tell him about that.

Thank you,
Jerry