Ruby on Rails authentication - MFA

I simply need a working example of a website that supports multi-factor authentication. But there are very specific constraints as the code is to be used by our in-house developer and adapted to existing work. This project must be compatible with Ruby 2.3.1 On the frontend: The website must prompt the user for the username, password, and mfa token. All three elements will be submitted in a single action. On the backend (authentication method to be carried out): The website must pass the username and password over to an ldap server using devise_ldap_authenticatable The website must pass the username and mfa token to a RADIUS server. It will be up to the developer to determine the specific method here. Both checks must pass before the user is allowed in. Login failures must give no indication which authentication element failed. Code must be written in a way that allows for retrieval of ldap attributes (email address, fullname, etc) upon successful authentication. Developer must have his or her own resources for testing the application and provide documentation regarding what variables need to be adjusted to match any given environment. The application need not do anything else. I just need a working example of MFA through RoR for our in-house developer to learn from.