I have followed instructions from the below post and integrated SAML flow.
https://community.apigee.com/articles/29201/sso-integration-via-saml-with-developer-portal.html
But I am always getting "Access Denied" when using /saml_login link. It is not redirecting to IDP's login page. I made changes to the source code which I got from pantheon Git repository for our org if this is of any help.