Background

The original code, to build “the same” Docker and Singularity containers, took the build strategy of having a Singularity recipe and Dockerfile in the same repository. Since we can import Docker into Singularity, I decided to only write one recipe (Dockerfile) and thus kill two birds with one stone.

Why use a SCIF recipe?

When we build a container, we usually need to start with a Dockerfile (or Singularity recipe) and it looks like this:

Dockerfile --> Dockerhub --> Docker Image
               Dockerhub --> Singularity Recipe --> Singularity Container

But what if we want to build both Docker and Singularity? We can either create one recipe type (and convert to the other) or have an installation of a recipe file that can be done any container technology. That is SCIF. Our workflow instead looks like this:

SCIF Recipe --> Dockerfile --> Dockerfile --> Docker Image
            --> Singularity Recipe --> Singularity Container

For additional background, see the associated post by @vsoch.