Web Apps behind Azure Application Gateway - what is the IP of outgoing requests

Question

I have multiple web apps on Azure that I want to put behind an Application Gateway in order to use a single domain name with path routing.

However, my web apps needs to connect to a db outside of Azure. So I wonder what will the IP of the requests from these web apps to the db would be? I hope it will be the gateway public IP so I only have to authorize one IP at my db provider but I don't find any docs to confirm it (or not).

Answer 1

So I wonder what will the IP of the requests from these web apps to the db would be?

If you want your web apps to connect a database outside Azure, you may need App service Environment. Because the Web Apps need VNet to connect other resources. Also, due to the date base is outside Azure , you need to create VPN gateway to connect it. This connection is between the Web App and the database, not Application Gateway and Database.

So, the IP of requests from those Web Apps is not the IP of Application Gateway, It depends on the VNet in App Service Environment.

This picture explains how this environment works:

I hope it will be the gateway public IP so I only have to authorize one IP at my db provider but I don't find any docs to confirm it (or not).

Also, if you still want to use one IP to connect other resources, you can also add Internal Loadbalancer to achieve that.

You can see more details about Integrating your ILB ASE with an Application Gateway to help your deploy resources.

Please let me know if this answer helps.