aarch64 Hosts (Raspberry Pi)

DNF manages aarch64 nodes exactly the same as x86_64 nodes: they are declared in etc/config.yaml, built and deployed with the same commands. Hardware support (kernel, firmware, bootloader) comes from the nixos-raspberrypi 🡕 flake.

Declare an aarch64 Host

A host’s architecture is set with the arch field, in the cpu[:board] format. When this field is absent, the host is a standard x86_64.

`arch` value	Machine
`x86_64` (default)	PC / x86_64 server
`aarch64:rpi02`	Raspberry Pi Zero 2 W
`aarch64:rpi3`	Raspberry Pi 3
`aarch64:rpi4`	Raspberry Pi 4
`aarch64:rpi5`	Raspberry Pi 5

hosts:
  - hostname: "pi"
    name: "Raspberry Pi du salon"
    zone: "maison:1.20"
    arch: "aarch64:rpi5"
    profile: "server"
    users: ["alice"]
    services:
      homepage:

How It Works

Generation — just generate validates arch then writes it as-is into var/generated/hosts.nix.
Interpretation — the framework splits cpu:board into a NixOS system (aarch64-linux) and a board model (rpi5 → raspberry-pi-5).
Hardware injection — for a Raspberry Pi board, the nixos-raspberrypi modules (kernel and vendor firmware, bootloader, binary cache) are automatically added to the node configuration.
Building — Colmena builds this node with a dedicated aarch64 nixpkgs, transparent to the rest of the fleet.

Build Prerequisites

Building aarch64 from an x86_64 administration machine requires one of these three approaches:

Enable aarch64 emulation on the administration machine (the deployer):

# on the host that runs deployments
boot.binfmt.emulatedSystems = [ "aarch64-linux" ];

Simple, but emulated building is slow.

Build on target: deploy with Colmena using build-on-target, the Raspberry Pi compiles itself (native but slow).
Remote aarch64 builder: delegate building to an ARM machine (fastest for a large fleet).

Install a Raspberry Pi

A bootable SD image boots the Pi, which is then integrated into the fleet like any other node (see initial installation).

Build the SD image (choose the attribute matching your model):

nix build .#nixosConfigurations.sd-image-raspberry-pi-5.config.system.build.sdImage

Write the image to the card:
Fenêtre de terminal
```
zstd -dc result/sd-image/*.img.zst | sudo dd of=/dev/sdX bs=4M status=progress conv=fsync
```
Replace /dev/sdX with the correct SD card (lsblk): dd overwrites the target without confirmation.
First boot — connected to the network (Ethernet, or Wi-Fi for boards without a wired port like the Zero 2 W), the Pi gets an address via DHCP (name dnf-install), with SSH enabled and the nix user authorized by the administration key (usr/secrets/nix.pub).
Declare then deploy — add the host to etc/config.yaml with its arch, run just generate, then deploy the actual configuration (deployment).