[derefr]

It's the build process for the container-image (i.e. the Dockerfile or equivalent) that the tooling being discussed here is analyzing; not the resultant container image, nor containers spawned from said image.

The goal is, presumably, to figure out when a given docker image was created in such a way that it burns in a vulnerable version of some library; so that the author can be alerted that they need to (update their Dockerfile and) rebuild their image.

"Dark matter", under this definition, is anything that gets injected during the build process of the image, that is not itself traceable to some other versioned package management system with vulnerable-version deprecation. Without such information, an automated agent like the one described in the article cannot then propagate deprecations from consumed package-versions to produced image-tags.

A good example of such "dark matter" would be a static binary built outside the Dockerfile using a CI system, where the CI then creates a docker image by running a Dockerfile that simply injects the expected prebuilt binary into an image with an ADD stanza. Does that binary contain vulnerable versions of embedded static libraries? Who knows?

[hakre]

Not sure it is that easy. The Docker API provides introspection for those as well as also there is no Light Matter only because the example project is not using an ADD stanza any longer but the Dockerfile context is from a tar ball created by that project as a reproducible build artefact.