Assuming each one of the rails app, go services, etc, are in their own subdirectory, hash the contents of the subdirectory and use that as one of the tags that

Assuming each one of the rails app, go services, etc, are in their own subdirectory, hash the contents of the subdirectory and use that as one of the tags that is stuck on the artifact. Look up the tag in your artifact store. If it doesn't exist, run your build scripts.