Method 1
Use Phoenix as a reverse proxy and route all Rails calls through your Phoenix Project, while re-implementing them in Phoenix one by one. This ensures that your app does not break and you can focus on one call at a time.
Example implementation: https://blog.fourk.io/replace-your-production-api-with-elixir-today-4426a8903642#.tw34zily8
Method 2
If you want to go with the umbrella approach, you can do something that I did. I had an internal API written in Node.js, and now wanted to work on the WebApp in Phoenix. Created an umbrella app, with two sub-apps; The Phoenix one, and a GenServer that simply spawns the node app on boot.
Related links:
- Start Node.js server with Phoenix
- Graceful shutdown of GenServers
- Shutdown an External process in Elixir
- Porcelain
Method 3
Mix method 1 and 2 up!
