What is the IP address of my shiny.io app?

Does anyone know how I can discover the IP address of the server running my app on shiny.io? I need to be able to pass the IP address to another application so that my shiny app can communicate with it.

Shinyapps.io runs applications in containers so I don't think each app has its own public IP but there is a list of the host servers' IPs for whitelisting if required, check this support article.