How to use Amazon ECR Public over IPv6

Source: Dev.to

Overview

If you want to pull Docker images from Amazon ECR Public using IPv6 (e.g., to avoid public IPv4 addresses and reduce costs), you need to use the newer domain name that supports IPv6.

Solution

Use ecr-public.aws.com instead of public.ecr.aws.

# Works with both IPv4 and IPv6
docker pull ecr-public.aws.com/ubuntu/ubuntu:latest

The older URI only resolves over IPv4:

docker pull public.ecr.aws/ubuntu/ubuntu:latest

Why a New Domain?

Amazon introduced ecr-public.aws.com rather than adding AAAA records to the original domain. While the exact reason isn’t publicly documented, a plausible explanation is to avoid breaking customers with mis‑configured networks. This approach, however, results in two valid URIs for the same image, which can be confusing.

Additional Notes

• The new domain is official but currently has limited documentation. References to it can be found in the Amazon ECR Public user guide PDF.
• The web gallery still lists image URIs using public.ecr.aws. Future updates may align the gallery with the IPv6‑compatible domain.
• Using the IPv6‑compatible domain helps avoid the need for workarounds like the Happy Eyeballs algorithm.

Hope this helps!