Building a NixOS SD image for a Raspberry Pi (Zero 2 w, 3, 3B+, 4)

Based off of: https://github.com/plmercereau/nixos-pi-zero-2 Many, many thanks, plmercereau!

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1. Update <pi>.nix

In particular, don't forget:

• to configure your wifi
• to add an admin user able to connect through ssh / password

2. Build the image

nix build -L .#nixosConfigurations.zero2w.config.system.build.sdImage

3. Copy the image in your sd card

sudo rpi-imager
# or use dd
DEVICE=/dev/<disk>
sudo dd if=result/sd-image/<pi>.img of=$DEVICE bs=1M conv=fsync status=progress

4. Boot your Pi
5. Get your IP

ifconfig wlan0

6. From another machine, rebuild the system:

PI_IP=<the-pi-ip>
SSH_USER=<the-admin-user-in-the-pi>
nix run github:serokell/deploy-rs .#zero2w -- --ssh-user $SSH_USER --hostname $ZERO2_IP

Notes

• The Zero 2 doesn't have enough RAM to build itself. An initial lead was to create a swap partition, but it turns out it was a bad idea, as it would have decreased the sd card lifetime (sd cards don't like many write operations). A zram swap is not big enough to work. Hence the use of deploy-rs.
  • Note that nixos-rebuild --target-host would work instead of using deploy-rs. but as nixos-rebuild is not available on Darwin, using deploy-rs that works both on NixOS and Darwin.
• boot.kernelPackages = pkgs.linuxKernel.packages.linux_rpi3 is not working...
• the sdImage.extraFirmwareConfig option is not ideal as it cannot update config.txt after it is created in the sd image.

See also

• this issue