Those dockerfiles are intended to be used for bundling assets like LambdaFunctions within the AWS-CDK toolkit.
Pushing them to dockerhub avoids the images to be built every time a bundling happens.
See https://aws.amazon.com/de/blogs/devops/building-apps-with-aws-cdk/
See available tags on docker hub
docker build -t nantisgmbh/aws-cdk-dockerfiles:nodejs14 .
docker push nantisgmbh/aws-cdk-dockerfiles:nodejs14