- Need to run more than one activity in a single container (this is an anti-pattern in other container technologies)
- HPC (and sometimes college) environments
- Want single-file distribution model (although doesn't support deltas)
- Cryptographically sign a SIF file without an external server
- Robust GPU support
You can achieve that with docker by `docker save image-name > image-name.tar.gz` and `docker load --input image-name.tar.gz`.
It likewise doesn't support deltas but there was a link here on HN recently to something called "unregistry" which allows for doing "docker push" to deploy an image to a remote machine without a registry, and that thing does take deltas into account.
I am sure that a lot of people have them deployed and don't even realize it. If you are using Gitea, Gitlab, Github, or any of their major forks/variations of you probably already have a place to put your images.
So I really don't know what the advantage of 'single file distribution model' is here.
This is probably why people don't bother sharing tarballs of docker images with one another even though it is has been a option this entire time.
If you're deploying to a server, I don't see a point in setting up a registry, regardless of how trivial it is. It seems even more trivial to just send the deployment package to the server.