You get your AWS bill. EC2 looks reasonable. RDS looks fine. Then there's a line item called "NAT Gateway" sitting at $800 and you have no idea why.
This is the charge that catches almost every team running Kubernetes on AWS. Here is exactly what it is, why it grows silently, and how to fix it in 20 minutes.
What NAT Gateway Actually Does
A NAT Gateway lets resources in your private subnets reach the internet without exposing them directly. Every byte of traffic that flows through it costs $0.045 per GB — on top of the hourly charge of $0.045 per hour ($32/month just for existing).
For small workloads that's negligible. For a K8s cluster with 20+ pods constantly pulling images, sending logs, and calling external APIs, it compounds fast.
