apptainer

# Apptainer - HPC Container Management

## Overview

The `apptainer` command manages Apptainer (formerly Singularity) containers for HPC-compatible workloads. It provides SIF image management with automatic GPU detection.

**Key Concept:** Apptainer is the HPC standard. Unlike Docker/Podman, containers run as the user (no root). SIF files are single-file images.

## Quick Reference

| Action | Command | Description |
|--------|---------|-------------|
| Build | `ujust apptainer build DEF` | Build SIF from definition file |
| Cache | `ujust apptainer cache [clean\|status]` | Manage Apptainer cache |
| Exec | `ujust apptainer exec IMAGE CMD` | Execute specific command in container |
| Inspect | `ujust apptainer inspect IMAGE` | Show SIF file metadata |
| Pull | `ujust apptainer pull IMAGE` | Download container image to SIF file |
| Run | `ujust apptainer run IMAGE` | Run container with default command |
| Shell | `ujust apptainer shell [-- CMD]` | Open interactive shell in container |

## Parameters

| Parameter | Long Flag | Short | Default | Description |
|-----------|-----------|-------|---------|-------------|
| action | (positional) | - | required | Action: pull, run, shell, exec, build, inspect, gpu, cache |
| image | `--image` | `-i` | `""` | SIF file path, image name, or DEF file |
| tag | `--tag` | `-t` | `""` | Image tag, output file, or cache subaction |
| cmd | (variadic) | - | `""` | Command to execute (use `--` separator) |

## Pull Images

### bazzite-ai Pod Images

```bash
# Pull nvidia-python (long form)
ujust apptainer pull --image=nvidia-python

# Pull with tag (long form)
ujust apptainer pull --image=nvidia-python --tag=testing

# Pull nvidia-python (short form)
ujust apptainer pull -i nvidia-python

# Pull with tag (short form)
ujust apptainer pull -i nvidia-python -t testing

# Pull jupyter
ujust apptainer pull --image=jupyter --tag=stable
```

### External Images

```bash
# Docker Hub
ujust apptainer pull --image=docker://ubuntu:22.04

# NVIDIA