I don't believe they use Nix at all.

Dev Containers are basically Docker Containers (either pulled from a repo or built from a Dockerfile) with some additional metadata attached so they can work as a Development Environment. Metadata includes stuff to configure debuggers, IDEs, etc.

While you can use nix derivations to build development containers, you still would need a Makefile / bash script specifying how to run them.

The devcontainer spec combines 3 things:

- How to build containers for a development environment (using Docker or docker-compose)

- How to run containers for a development environment (volumes to mount, environment variables, commands to execute after containers are running, where the project will be mounted...)

- Which VS Code configuration to install and use (including extensions) within the development environment

yeah don't really like all this. I mean if ppl are use to Dockfiles or dock compose files, then just stick with that can change the underlying tech to Nix, firejail, fire cracker or whatever. It is quite annoying to have a mega corp popping up with these different container tech that pretty much does the same thing.

Nix derivations: Microsoft E.E.E. edition.