These containers contain an entire operating system (OS) like Ubuntu, along with every program or dependencies you might want to install in it. As for Docker containers, and Apptainer can still edit ...
Host machine (Pop!_OS) │ ├── Podman (rootless) │ ├── slurmctld ← head/login node (submit jobs here) │ ├── node1 ← compute node 1 (runs slurmd) │ └── node2 ← compute node 2 (runs slurmd) │ ├── shared/ ...