Developer documentation

Building

The build system uses Nix which must be installed before anything can be built. Start by setting up the development/operations environment:

$ nix-shell

Testing

The test system uses Nix which must be installed before any tests can be run.

Unit tests are run using this command:

$ nix-build nixos/unit-tests.nix

Unit tests are also run on CI.

The system tests are run using this command:

$ nix-build nixos/system-tests.nix

The system tests boot QEMU VMs which prevents them from running on CI at this time. The build requires > 10 GB of disk space, and the VMs might be timing out on slow or busy machines. If you run into timeouts, try raising the number of retries.

It is also possible go through the testing script interactively - useful for debugging:

$ nix-build -A private-storage.driver nixos/system-tests.nix

This will give you a result symlink in the current directory. Inside that is bin/nixos-test-driver which gives you a kind of REPL for interacting with the VMs. The kind of Python in this testScript is what you can enter into this REPL. Consult the official documentation on NixOS Tests for more information.

Updatings Pins

Nixpkgs

To update the version of NixOS we deploy with, run:

That will update nixpkgs-2015.json to the latest release on the nixos-21.05 channel.

To update the channel, the script will need to be updated, along with the filenames that have the channel in them.

Gitlab Repositories

To update the version of packages we import from gitlab, run:

That will update the package to point at the latest version of the project.The command uses branch and repository owner specified in the repo.json file, but you can override them by passing the --branch or -owner arguments to the command. A specific revision can also be pinned, by passing -rev.

Architecture overview