Issue description

I intend to start using nixpkgs' singularity-tools for hpc applications.
What follows is a list of hindrances and minor annoyances that I've immediately encountered.
The list is mostly for myself: I'm opening the issue to make this visible and maybe motivate people to voice ideas and comments.
Cf. this read on singularity with Nix for more inspiration

• VM-free image builds: Beat singularity-tools up to shape #177908 (comment)

• Singularity needs patching to make images reproducible: singularity-tools.buildImage: non-deterministic #279250

  • mkfs generates random UUIDs
  • SIF metadata (information about the builder, timestamps)

• Give users control over contents, in particular allow to remove bash: currently including bash manually results in singularity-tools.buildImage throwing obscure errors

• Annoyance: we can compute diskSize from the built contents instead of choosing an arbitrary constant

• Hindrance: failing to pack any cuda-enabled dependencies. The error says: ... Cannot allocate memory. My /tmp is on disk, and I don't seem to be running out of RAM, so this message might be just another version of "not enough space left on (squashfs) device"

• Hindrance: buildImage interface doesn't expose

  • Environment variables (or any other metadata, like apphelp)
  • Services ("container instances")

• ...

• Get this merged: singularity: fix defaultPath and reflect upstream changes #158486

CC (possibly interested) @ShamrockLee @jbedo