Shared database models architectural pattern

At work, we have two applications in separated servers:

• Rails API and web dashboards in Heroku
• Rails Background jobs processing in a DigitalOcean server.

Both apps communicates by HTTP and use the same database. I need to do a mass email sending. I think the better way is to put that processing in the background jobs server for don't impact in the performance of the Heroku server.

Then I need to replicate some models from the Heroku server to the DigitalOcean server app. So I think that maybe is a better idea extract all the models and do it available as a gem for any application.

I would like know if is a corect way to do that or ther is a better way or pattern.