Here I am trying to create a node.js website the docker file and push the image to ECR and also use ECS Services. https://www.digitalocean.com/community/tutorials/how-to-build-a-node-js-application-with-docker use the above link to help you out, for any more doubts you have https://docs.docker.com/language/nodejs/build-images/ one more to help out, its from official docker account blog.

Official Docker link for Multiple Code Dockerfile Building: https://docs.docker.com/language/