NixOS template for RPi 4

This template allows to install & manage a NixOS distribution on an RPi4.

Host Preparation

If the host is not an aarch64-linux machine, it must have nix binfmt configured: boot.binfmt.emulatedSystems = ["aarch64-linux"];.

Initial installation sdcard

There are several things to edit in the flake.nix for the installation:

• "<MY NETWORK>" & <PASSWORD> in flake.nix
• # My SSH Key in flake.nix

You can then generate a sd image using nix build .#rpi4-install. Note that when using binfmt this can take a long time.

The result will be located in result/sd-image/nixos-sd-image-23.05.20231216.b2566f4-aarch64-linux.img.zst It can be written with sudo zstdcat '.zst' -o /dev/.....

Tip: to see more details on the build its possible to run nom build ... instead of nix build ....

Note that on the first boot there most likely won't be wifi. To enable wifi a systemctl restart wpa_supplicant might be needed.

Deployment of the full configuration

After logging in the rpi4 you need to fetch the system ssh key (located at /etc/ssh/ssh_host_ed25519_key.pub) and write it in secrets.nix.

You can then run nix run .#agenix -- -e wifi.age in the secrets directory to write the wifi key. The file must be formatted like this:

WIFI_KEY="<key>"

Then in config.nix <MY NETWORK> must be substituted with the correct network name, and the SSH key should be filled in.

In update.sh the IP must be filled in HOST, and then the configuration can be deployed using update.sh