Singularity Containers

Written for software version 2.5.2.

Singularity is a virtualization tool that allows users to containerize workflows, applications, and environments to allow for portability, customization, and reproducibility. Additionally, Singularity is integrated with the Message Passage Interface (MPI) to be used in High Performance Computing (HPC) systems as well as Virtual Machines (VMs) which enables a seamless workflow environment. Lastly, you may also utilize Docker containers with Singularity!

Note: These instructions are adapted from the official Singularity documentation.

Prerequisites

• A command line environment in Ubuntu or CentOS.

• Software dependencies (these may be numerous):

  • Ubuntu

      sudo apt-get update && \
      sudo apt-get install \
      python \
      dh-autoreconf \
      build-essential \
      libarchive-dev

  • CentOS

      sudo yum update && \
      sudo yum groupinstall 'Development Tools' && \
      sudo yum install \
      libarchive-devel \
      squashfs-tools

Singularity Installation

The most up-to-date version is housed in a GitHub repository. The software is installed from the source. Use Git to clone the repository and run the following commands.

git clone https://github.com/singularityware/singularity.git
cd singularity
./autogen.sh
./configure --prefix=/usr/local --sysconfdir=/etc
make
sudo make install

Building a Container using an Existing Container

The following command executes the build command, specifies the path and name of the container (lolcow.simg), and provides the location of the container on the Singularity Hub (shub://GodloveD/lolcow).

singularity build lolcow.simg shub://GodloveD/lolcow

Interacting with Containers

There are three primary ways to interact with a Singularity container.

1. Run: Creates an ephemeral container that runs a predefined script

   singularity run lolcow.simg or ./lolcow.simg

2. Shell: Supplies a command line prompt to interface with the container

   singularity shell lolcow.simg

3. Execute: Sends a command into the container and provides output

   singularity exec lolcow.simg

Congratulations! You have successfully deployed a Singularity container!

As some next steps, navigate to the official Singularity documentation to learn more about the Singularity Hub, Docker Hub and building a container from scratch.