Multiple applications with same model and db


I’m developing an enterprise web applications with rails.

I’m trying to figure out the best way of using the same models and database between 2-3 rails applications.

My project consists of different applications such as user app, customer app and admin app.

All of these 3 will use the same database and almost the same models.

I want to create 3 different rails app and deploy them to different servers.

What might be the best way of sharing the models?