A Practical FinOps Win: AWS NAT Costs
AWS NAT Gateways are frequently treated as a default component of VPC design. They are simple to deploy, highly available, and largely invisible once in place. In multiple Availability Zone environments, the recommended pattern is to deploy one NAT Gateway per AZ and route private subnets to their local gateway. While operationally convenient, this approach comes with a fixed and often under-examined cost. This post documents an alternative approach: replacing three managed AWS NAT Gateways with three self-managed NAT instances running FreeBSD on t4g.nano EC2 instances. The focus is on the mechanics of the design, the operational behaviour of FreeBSD as a routing platform, and the financial implications of the change. ...