Karpenter amiSelectors based on image alias (calver)

[pmcenery-bl]

TL;DR

I'm trying to use Renovate to automate updates for AMI selectors in Karpenter that use alias-based calendar versioning [1], e.g.:

[...]

amiSelectors:
- alias: al2023@v20250519

[...]

I've tried the amazon-machine-image data source but this seems to only be able to handle looking up and returning the ami ID (ami-XXXXXXX) rather than the Name.

I want to use image alias rather than image id as I have a single linux EC2NodeClass which covers both amd64 and arm64. If I switched to ami id, I'd need separate EC2NodeClass for each of these

According to the NodeClass documentation[2], the way to find the alias is by AWS SSM parameter lookup rather than EC2 describe-images. e.g.

export K8S_VERSION="1.32"
aws ssm get-parameters-by-path --path "/aws/service/eks/optimized-ami/$K8S_VERSION/amazon-linux-2023/" --recursive | jq -cr '.Parameters[].Name' | grep -v "recommended" | awk -F '/' '{print $10}' | sed -r 's/.*(v[[:digit:]]+)$/\1/' | sort | uniq

I'm happy to contribute something, but I'd like some guidance on the preferred way to deal with this. Where should I start? I suspect an "amazon-ssm-parameter" data source might be suitable for this?

References

• [1] - Karpenter managing amis
• [2] - Karpenter NodeClass