Map slurm user inside containers

For all the http services containerized via Singularity/Apptainer and providing a shell, most of the slurm commands fails (e.g. sbatch, srun...) due to the fact that the user set in slurm.conf/slurmctld.conf is not mapped in the user namespace of the container.

It might worth to understand:

• if it is possible to map it in a portable way (best case scenario);
• as an alternative, if a user with the same username/uid/gid defined in the %post section can cheat the slurm configuration to allow the submission (this seems unlikely, and not portable)