How to use Singularity in docker container?

Question

I have a question about the official Snakemake container image.
https://hub.docker.com/r/snakemake/snakemake/dockerfile

In this Dockerfile, singularity will be installed. As far as I know, the --privileged argument seems to be required to use singularity in a docker container.
docker run -it --privileged snakemake/snakemake ........

However, I think the --privileged argument is insecure from a security standpoint, so it would be preferable not to use it if possible.

Can anyone tell me the proper way to use singularity in a docker container?

Thanks,

Answer 1

The --privileged flag is the recommended and only way to run singularity in Docker.

Use of --privileged is not bad in itself, it is also used for running Docker-in-Docker, but it does allow the possibility of container escape. Follow best practices, build your own images and you should be okay.