Making requests to external hostnames from backend pool services

Question

When using the Azure Application Gateway, is there a way for services in the backend pool to make requests through the frontend IP of the gateway, in order to request public URLs?

In this example, the VM wants to make a request that hits the App Service.

There are many usecases for this. For example, the example.com/bar url could be a user submitted url, that the VM application needs to request to download an image.

Answer 1

Unfortunately this is not possible, Application Gateway does not have a way to alter outbound traffic on members on the backend pool. Azure Load Balancer can, and you can view more information about outbound connections with a VM Here. That doc mainly refers to Load Balancers, but describes how VMs send outbound requests as well.

The easiest way to control the IP that your VMs send requests from is to use a Public IP on the VM, or you can use Azure Virtual Network NAT to consolidate outbound connections inside your Virtual Network.