AWS Lambda VPC Configuration: The Complete Guide to Private Networking and Cost Optimization with NAT Instances

AWS Lambda VPC Configuration: The Complete Guide to Private Networking and Cost Optimization with NAT Instances Three months ago, I got a $400 AWS bill that made me question everything I knew about serverless architecture. The culprit? NAT Gateways supporting Lambda functions that barely handled 10,000 requests per month. That’s when I learned the hard way that “serverless” doesn’t mean “cheap” when you need proper networking. After weeks of deep-diving into VPC configurations, NAT alternatives, and cost optimization, I cut our Lambda networking costs by 85% while maintaining security and performance. Here’s everything I learned about running Lambda functions in VPCs the cost-effective way. ...

July 27, 2025 · 20 min