Azure Container Apps - Scale Set Instances consuming 58 IP Addresses

Question

In our Container Apps environment with a VNET we have noticed that a Scale set instance will consume 58 IP Addresses. Why would that be the case when the container app is provisioned with only a single max replica? What happens in the background when we provision a new Container App?

Answer 1

The Azure Container App infrastructure uses Azure CNI for network connectivity in order for each container to receive an IP from the underlying virtual network/subnet. As such, the Azure CNI driver reserves IP addresses for each underlying node, the number of IPs reserved is dependent on the ACA team's settings for how many pods are able to be scheduled per node, which I don't believe has been shared publicly.

Answer 2

Thanks, I should have posted the answer, I was given the same information on a support ticket I had opened. By using a /16 subnet instead of /23, we seem to have gotten past the issue.