I’ll introduce how I moved from private subnet to public subnet to reduce costs when Amazon VPC NAT Gateway charges became expensive.

Background: ECS Scheduled Tasks Downloading & Uploading from the Internet

I was using ECS Scheduled Tasks to download and upload from the internet, but since these were placed in private subnets, the NAT Gateway charges became expensive.

Moving from Private Subnet to Public Subnet

The following article was helpful for reducing NAT Gateway costs:

• そのトラフィック、NATゲートウェイを通す必要ありますか？適切な経路で不要なデータ処理料金は削減しましょう | DevelopersIO

In this case, placing the resources in public subnets solved the problem, as mentioned in the above article.

Can it be placed in a public subnet?

When most traffic is to non-AWS resources, consider whether the target AWS resources can be placed in public subnets to allow direct internet access without going through NAT Gateway. If you were wasting money on downloads from the internet, changing to direct access to IGW will make data-in transfer charges zero.

「トラフィックのほとんどが非 AWS リソースの場合、対象となる AWS リソースをパブリックサブネットに配置し、NAT Gateway を介さずに直接インターネットへのアクセスが可能であるか検討しましょう。インターネットからのダウンロードで浪費していた場合、IGW への直接アクセスに変更することでデータインのデータ転送料金はゼロになります。」

That’s all from the Gemba on wanting to reduce AWS costs.