TODO

• Create a netbootable netbootImage output instead of sdImage
• Provide a nixosConfiguration for this netbootImage that runs all of the infrastructure for booting it via PXE and other methods
• Derive configuration values from the scale-network repo as a Flake input, or merge with the scale-network repository
  • Merging with the scale-network repository requires requires refactoring of that repository, or else it is not worth merging with it. This kiosk repository is better as a separate Flake until refactoring and more Nixification occurs upstream in the scale-network repository.

Building

If you're already on NixOS and have Nix installed and can emulate arm64 transparently then just:

nix build .#pi-kiosk-sdImage

Otherwise, follow the instructions below before running this command.

x86_64-linux (NixOS)

If you're running NixOS and want to use this template to build the Raspberry Pi 4 Image, you'll need to emulate an arm64 machine by adding the following to your NixOS configuration.

{
  boot.binfmt.emulatedSystems = [ "aarch64-linux" ];
}

Then you will be able to run nix build .#pi-kiosk-sdImage and get a result you can flash to an SD Card and boot.

After you've booted, you can rebuild the nixosConfiguration on the Pi. For example, by running nixos-rebuild --flake socallinuxexpo/scale-kiosk#pi-kiosk and should never have to re-image again unless you want to.

On x86_64-linux (any distribution of Linux)

Get Nix and enable flakes, for example via the DetSys Nix installer

curl --proto '=https' --tlsv1.2 -sSf -L https://install.determinate.systems/nix | sh -s -- install

Or if you prefer a single 21M~ file, get a statically compiled Nix binary

curl -L https://hydra.nixos.org/job/nix/master/buildStatic.x86_64-linux/latest/download-by-type/file/binary-dist > nix
chmod +x ./nix

Run the Binfmt SDK from the root of this repo in order to enter a virtual machine which is itself capable of emulating arm64. You will then be able to clone the repo and build any of the arm64 outputs from this flake.

nix run .#binfmt-sdk-nixos-shell

What is binfmt and why is it needed?

To avoid the need to cross-compile anything, and to make use of cache.nixos.org, building via binfmt will actually spin up QEMU and emulate an arm64 machine for every package/derivation that needs to be compiled. Binfmt is a kernel feature that will allows programs like QEMU to be span up whenever any program tries to spawn a process for a foreign architecture.