how to build singularity container from dockerfile

Question

I want to build singularity container from dockerfile.

I have pulled and run docker images from docker hub with singularity.

singularity pull docker://ubuntu:latest

I have also build the image from singularity recipe file.

singularity build  cpp.sif singularity_file

But I want to build singularity image from dockerfile.

Anyone know how to do it. Is it possible ???

Answer 1

You cannot build a singularity container directly from a Dockerfile, but you can do it in a two-step process.

docker build -t local/my_container .
sudo singularity build my_container.sif docker-daemon://local/my_container

Using docker://my_container look for the container on Docker Hub. When you use docker-daemon, it looks at your locally built docker containers. You can also use Bootstrap: docker-daemon in a Singularity definition file.

Answer 2

You can transform a Dockerfile into a singularity recipe or vise-versa using Singularity Python. Singularity Python offers some very helpful utilities, consider to install it if you plan to work with singularity a lot

pip3 install spython # if you do not have spython install it from the command line

# print in the console
spython recipe Dockerfile

# save in the *.def file
spython recipe Dockerfile &> Singularity.def

If you have problems with pip you can download spython or pull a container as described in Singularity Python install. Find more about recipe conversion here