In some cases, it is difficult to assign a large address space in the enterprise network when using services that require a large address space such as Azure Container Apps. This sample divides the virtual network of the landing zone into routable and non-routable, and assigns a carrier-grade NAT address space (RFC 6598 - 100.64.0.0/10) to the non-routable side.

The basic idea is based on the following article.

Prevent IPv4 exhaustion in Azure

• On-premises to Landing Zones
• Landing Zone to Landing Zone
• Landing Zone to On-premises

• Azure Firewall rules of this sample are only the minimum network rules required for SNAT. Add as needed.
• Source IP change due to SNAT of Azure Firewall. You can insert the HTTP/HTTPS X-Forwarded-For header with the application rule of Azure Firewall.
• You need to check if Azure services are using the RFC 6598 address space. Azure Container Apps uses part of that address space, so this sample has been designed to exclude that range.