question about Singularity bootstap from docker

[Jia94]

Excuse me !
There is a docker image that built on my own,so if I want to creat one Sinualrity image based upon this docker image ，do I have to pull the docker image to Docker Hub? and then how I write the section of "From"?

[vsoch]

The easiest thing is to:

1. Get the image on Docker Hub. You can do that with push or an automated build from a Github repository. I like the second because I can just put my Dockerfile on Github, and it will build for me when I push commits :)
2. Once the image is done building (green successful build) you Bootstrap recipe would look like this:

Bootstrap: docker
From: Jia94/image-name

...

3. Then build or pull. You could also just build it directly, or pull, either of these would work:

# Without definition file
singularity pull docker://Jia94/image-name
sudo singularity build myimage.simg docker://Jia94/image-name

# With definition file "Singularity" shown above
sudo singularity build myimage.simg Singularity

The only benefit to using a definition file is if you want to modify the image after build on Docker Hub. If not, you would be able to just pull or build without it.