Containers are a useful way to take software produced on one system and make it portably run on another. A container image contains, not only the application you wish to run, but also most of the operating system is was created on - everything apart from the kernel.

The most popular container system is called Docker, which is aimed at use on laptops and desktops. Unfortunately, Docker is unsuitable on a machine like Hamilton, but we instead provide a compatible system called Singularity.

As an example, this is how to download and run the ubuntu image from Docker Hub on one of Hamilton's login nodes:

$ module load singularity

$ singularity build ubuntu_latest.simg docker://ubuntu:latest
... skip some output ...
INFO:    Creating SIF file...
INFO:    Build complete: ubuntu_latest.simg

$ singularity shell ./ubuntu_latest.simg
Singularity> cat /etc/lsb-release
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=20.04
DISTRIB_CODENAME=focal
DISTRIB_DESCRIPTION="Ubuntu 20.04.2 LTS"
Singularity>

Hamilton's compute nodes unfortunately do not currently have access to Docker Hub to download images. Once you have downloaded an image to a file on one of the login nodes, you will be able to run the container in a job script.

Example job script my_container_job.sh, to run the copy of bash within the cached Ubuntu image, using a single CPU core:

#!/bin/bash

# Request resources:
#SBATCH -n 1          # 1 CPU core
#SBATCH --mem=1G      # 1 GB RAM
#SBATCH --time=6:0:0  # 6 hours (hours:minutes:seconds)

# Run on the queue for serial ("sequential") work
# (job will share node with other jobs)
#SBATCH -p seq7.q

# Make singularity available:
module load singularity

# Commands to be run:
singularity run ./ubuntu_latest.simg /bin/bash -c "echo hello"

Submit it to the queue with the command: sbatch my_continer_job.sh