DEV Community

loading...

Discussion on: How we lost $800/mo with Amazon ECS Fargate

Collapse
davisengeler profile image
davis • Edited

I've been worried about exactly this after building something with Fargate recently. I noticed the 'restart loop' behavior if you push up a crashing version, and it scared me into looking closer at how they bill for that image transfer. Happy to come across your post and discussion in the comments, but hate it caused such a big bill for you all. That's scary.

I'm a bit confused in my case, though, because my image in ECR is like 1.5GB and I'm not seeing any sort of transfer charges for that data. I have Fargate charges already, but nothing related to the transfer of the image (it's been a week or two with hundreds of cold starts). Is it possible those charges are much more delayed than Fargate's?

If I'm not actually being charged for it, how is that happening? I actually have 0 NAT Gateways on my account (that I can tell), yet I'm able to use my image from ECR in Fargate tasks.

Should I expect a big surprise bill coming soon? Based on the phrasing of their docs, I would have expected a cost of roughly 10¢ per cold start in my case since the first one I do blows past the ECR free tier for transfer out.

Collapse
davisengeler profile image
davis

Found this in the ECR pricing documentation:

Data transferred between Amazon Elastic Container Registry and Amazon EC2 within a single region is free of charge (i.e., $0.00 per GB).

I guess since EC2 is underlying Fargate and I'm using the same region, it's free in this case.

Question: What was the need for your NAT Gateway in your configuration? I don't have one and ECR <–> Fargate seem to be communicating fine.

Collapse
raphael_jambalos profile image
Raphael Jambalos Author

Do you have VPC endpoints set up for your network? That's probably why your fargate instances can fetch ECR repositories without much charges.

If you don't have NAT gateway set up (and no VPC endpoint), you're probably using your Fargate containers in your public subnet where its using the Internet Gateway to fetch images from ECR. I'm not sure if Internet Gateways have a per-GB charge, I think it doesnt. If this is the case, you probably don't have to worry about this problem

Thread Thread
davisengeler profile image
davis • Edited

Thanks for the insights!