Running singularity without installing using docker

Singularity is another container platform, similar to docker. It is widely used in high performance computing world, due to better security and portability.

But many of us are already familiar with docker, since that is the most widely used container technology. To try to learn singularity, the easiest way is to use docker that we already have inside our machine and launch singularity from there. 

We can run singularity image from quay.io by running below command

docker run --privileged --rm quay.io/singularity/singularity:v3.10.0 --version

singularity-ce version 3.10.0

In order to download image from docker and convert it into sif, we can use this

docker run --privileged --rm -v ${PWD}:/home/singularity quay.io/singularity/singularity:v3.10.0 pull /home/singularity/alpine_latest.sif docker://alpine

Once downloaded, we can run a command using the newly downloaded image

docker run --privileged --rm -v ${PWD}:/home/singularity quay.io/singularity/singularity:v3.10.0 exec /home/singularity/alpine_latest.sif cat /etc/os-release

NAME="Alpine Linux"

ID=alpine

VERSION_ID=3.15.4

PRETTY_NAME="Alpine Linux v3.15"

HOME_URL="https://alpinelinux.org/"

BUG_REPORT_URL="https://bugs.alpinelinux.org/"

Even though this is probably the easiest way to use singularity in a docker installed machine, but the command can get pretty confusing. It is highly advisable, that once you have tested enough and decided to use singularity, to actually install it in your system.