Apptainer within Docker / Rocky 8

A quick way to do apptainer image builds on machines without apptainer. Generally for images used within HPC facilities, etc.

Starting / Building

• to bring up a container you can work in:

docker compose -f docker-compose-tty.yml up

then you can use apptainer inside the container with:

docker exec -it apptainer-rocky-builder /bin/bash

• to just do a build: aptcont.sif and aptbuild.def are the expected output and input.
• Create ./builds/aptbuild.def
• sif container will be aptcont.sif when done

docker compose -f docker-compose-builder.yml up