I highly recommend you try the sails-generate-auth generator. It is passport-based and creates the entire authentication level for your sails.js application, including local policy (user / password), OAuth2.0, and OpenID.
Sails-generate-auth will create two new models for you (User, Passport), an authentication controller, a service, and route and policy settings. Therefore, if you want to apply authentication to an existing application, it would be safer to create a new sailing application, generate an authentication level using sails-generate-auth, test it a little and then copy the necessary files to the original application.
Hope this helps.
Edit
sails-auth . sails-generate-auth, , .