Not sure about Earthly as I’ve never used it, but for Nexus and other artifactory solutions around package repos:

1. Don’t need to set up anything. No need to set up an apt repo and push packages or configure a mirror, because StableBuild already caches the complete registry and thus has everything. 2. Don’t need to think about the complete package list when pushing files to artifactory. Have packages cached from 3 months ago, now want to add another one? Oops, not in Nexus, and the current versions in the Ubuntu package registry are not compatible with your cached versions -> need to update the full dependency tree. 3. Integration is trivial. Three lines to your Dockerfile and done. 4. Can retroactively fix things. Knew that this container built 4 weeks ago? Ok use that as a pin date -> fixed.

Then there’s some stuff, like the immutable Docker pullthrough cache and history pypi mirror that I haven’t seen before (but I’d like to learn if others are doing this :-)).