The Dockerfile in this repository builds Apptainer. The resulting Docker image can be used on any system with Docker to build Apptainer images. This project is targeted towards high-performance computing users who have Apptainer/Singularity installed on their clusters but do not have Apptainer/Singularity on their local computers to build images.

Note: This project previously built Singularity. See the Linux Foundation post regarding the name change to Apptainer.

In the following example, we convert an existing Docker image to Apptainer format.

$ docker pull alpine:3.18.2
$ docker run --rm -v /var/run/docker.sock:/var/run/docker.sock -v $(pwd):/work \
    kaczmarj/apptainer build alpine_3.18.2.sif docker-daemon://alpine:3.18.2

This output .sif file will be owned by root, so you can change ownership:

sudo chown USER:GROUP alpine_3.18.2.sif

With the following command, we build a small Apptainer image defined in test_alpine.def. This Apptainer image will be saved in the current directory myimage.sif.

$ docker run --rm --privileged -v $(pwd):/work kaczmarj/apptainer \
  build myimage.sif test_alpine.def

One can run a Apptainer image within this Docker image. This is not recommended, but it is possible.

$ docker run --rm --privileged kaczmarj/apptainer \
  run shub://GodloveD/lolcow

Here is the output:

INFO:    Downloading shub image
87.6MiB / 87.6MiB [======================================================================================================================================================] 100 % 1.4 MiB/s 0s
 _________________________________________
/ He that is giddy thinks the world turns \
| round.                                  |
|                                         |
| -- William Shakespeare, "The Taming of  |
\ the Shrew"                              /
 -----------------------------------------
        \   ^__^
         \  (oo)\_______
            (__)\       )\/\
                ||----w |
                ||     ||

Apptainer version 1.2.0:

$ docker build --build-arg APPTAINER_COMMITISH=v1.2.0 -t apptainer:1.2.0 .

Bleeding-edge (main branch):

$ docker build --build-arg APPTAINER_COMMITISH=main -t apptainer:latest .