Fucked

• Docker.

This is the one that gets you a job. It also requires installing, running and dealing with a daemon's insecurities.

Raw OCI Tools

• skopeo; a tool to upload/download OCI container images.
• umoci; a tool to modify OCI container images.
• runc; a tool to run OCI containers.

You drive these from shell scripts or mkfiles and get images out.

Docker-compatible

Warning: These are Redshit.

• podman; drop-in replacement for docker.
• buildah; can build Dockerfiles without docker.

Honorable mentions

I miss rkt.

Not sure if kubernetes is fucked or not. People tell me if you need what it does, then it's great, but you probably don't need what it does.