Amazon AWS Security Group - Allow Microsoft Azure Web App IP Address

This is the first time I've published a web app on Azure. I have a SQL Server database on Amazon AWS that I'm connecting to. I need to set the security group to allow the Azure Web App to connect. How do I get the IP address of the Azure web app? From what I understand about Azure, the web apps have a rotating IP address because they're on shared servers. What can I tell the security group to allow?