Install NixOS on Hetzner Cloud
Hetzner Cloud in 2023 offers amd64 instances on both Intel and AMD hardware, as well as arm64 instanced based on the Ampere Altra Q80, in three locations in Europe, as well as two in America.
The pricing of the arm64 instances is generally considered very competitive, compared to similarly specced amd64 instances.
Installation
There are several ways to install NixOS, such as the "traditional" ISO installation, nixos-infect or nixos-anywhere.
Tradition ISO installation
TODO
nixos-anywhere
The tutorial assumes you already have an account on Hetzner Cloud, and no prior access to a system with NixOS or nix CLI utility installed:
- Create a temp folder for future use. Run:Note: this folder will be mounted into docker container on the next step. Having the folder on the host system enables editing files using a familiar editor, available on the host system, such as VS Code or neovim.
mkdir /tmp/my-first-flake
- Enter docker container. Run:Note: this is done in a container in order to reduce the "setup footprint and residue", allowing to throw away this setup environment quickly.
docker run --rm --interactive --tty --mount type=bind,source=/tmp/my-first-flake,target=/tmp/my-first-flake alpine:3.20 ash
- Install
nix
andhcloud
CLI utilities. Run:apk add nix hcloud openssh
- Authenticate
hcloud
CLI utility. Run:hcloud context create my-first-context
- When asked, enter value of the token in the prompt. Note: the token with "Read/Write" permissions can be obtained on a project page inside Hetzner Cloud: https://console.hetzner.cloud/projects/0000000/security/tokens
- Create an SSH key:
ssh-keygen -t ed25519 -f /root/.ssh/id_ed25519 -N ''
- Upload your public key to Hetzner:
hcloud ssh-key create --name 'My public key' --public-key-from-file /root/.ssh/id_ed25519.pub
- Create a VM on Hetzner. Run:Write down the IP. Note 1: this tutorial uses
hcloud server create --name my-hetzner-vm --type cpx21 --image ubuntu-24.04 --location fsn1 --ssh-key 'My public key'
cpx21
VM instance type which corresponds to an x86 architecture marchine with 3 CPU cores and 4GB of RAM, andfsn1
location which corresponds to a data center in the city of Falkenstein in Germany. A list of all instance types can be obtained by running commandhcloud server-type list
, while a list of all locations can be obtained by runninghcloud location list
command. Note 2: Hopefully, Hetzner Cloud team will support NixOS disk images soon, see Could we convince Hetzner to add Nixos as a standard image choice. - On your host computer, create a folder. Run:
mkdir -p /tmp/my-first-flake/my-vms/my-hetzner-vm/
- Using a code editor on your host computer, create 4 files. File contents, as well as the location of where to put corresponding file are indicated below:
# /tmp/my-first-flake/my-vms/my-hetzner-vm/hardware-configuration.nix { config, lib, pkgs, modulesPath, ... }: { imports = [ (modulesPath + "/profiles/qemu-guest.nix") ]; boot.initrd.availableKernelModules = [ "ahci" "xhci_pci" "virtio_pci" "virtio_scsi" "sd_mod" "sr_mod" ]; boot.initrd.kernelModules = [ ]; boot.kernelModules = [ ]; boot.extraModulePackages = [ ]; swapDevices = [ ]; networking.useDHCP = lib.mkDefault true; nixpkgs.hostPlatform = lib.mkDefault "x86_64-linux"; }
# /tmp/my-first-flake/my-vms/my-hetzner-vm/disko-config.nix { disko.devices = { disk = { main = { type = "disk"; device = "/dev/sda"; content = { type = "gpt"; partitions = { boot = { size = "1M"; type = "EF02"; priority = 1; }; ESP = { size = "512M"; type = "EF00"; content = { type = "filesystem"; format = "vfat"; mountpoint = "/boot"; }; }; root = { size = "100%"; content = { type = "filesystem"; format = "ext4"; mountpoint = "/"; }; }; }; }; }; }; }; }
Note: the value of# /tmp/my-first-flake/my-vms/my-hetzner-vm/configuration.nix { config, lib, pkgs, ... }: { imports = [ ./hardware-configuration.nix ./disko-config.nix ]; boot.loader.grub.enable = true; services.openssh.enable = true; users.users.eugene = { isNormalUser = true; extraGroups = [ "wheel" ]; initialHashedPassword = "$y$j9T$2DyEjQxPoIjTkt8zCoWl.0$3mHxH.fqkCgu53xa0vannyu4Cue3Q7xL4CrUhMxREKC"; # Password.123 }; programs.neovim = { enable = true; defaultEditor = true; configure = { customRC = '' colorscheme habamax ''; packages.packages = { start = [ pkgs.vimPlugins.nerdtree ]; }; }; }; system.stateVersion = "24.05"; }
initialHashedPassword
above was obtained usingmkpasswd
command in Linux, and corresponds toPassword.123
string used as password.Note: all these files constitute what's known as a nix flake. The flake in question is small, though not exactly a minimal one.# /tmp/my-first-flake/flake.nix { inputs = { nixpkgs = { url = "github:NixOS/nixpkgs/nixos-24.05"; }; disko = { url = "github:nix-community/disko"; inputs = { nixpkgs = { follows = "nixpkgs"; }; }; }; }; outputs = inputs@{ self, nixpkgs, ... }: { nixosConfigurations = { my-hetzner-vm = nixpkgs.lib.nixosSystem { system = "x86_64-linux"; modules = [ ./my-vms/my-hetzner-vm/configuration.nix inputs.disko.nixosModules.disko ]; }; }; }; }
- Build NixOS from flake. Run:Note: replace
nix run --extra-experimental-features 'nix-command flakes' github:nix-community/nixos-anywhere/1.3.0 -- --flake /tmp/my-first-flake#my-hetzner-vm root@0.0.0.0 --build-on-remote
0.0.0.0
with an IP address obtained during an earlier step.
The NixOS on Hetzner is installed!
Let's do a few more steps to customize the installation.
- Copy flake files onto the server. Run:Note: again, replace
scp -r /tmp/my-first-flake eugene@0.0.0.0:~/
0.0.0.0
with an IP address obtained viahcloud server ip my-hetzner-vm
. - Using
neovim
editor on the VM, modifyconfiguration.nix
to include a package containing Elixir programming language runtime foreugene
user. Run:Edit thenvim my-first-flake/my-vms/my-hetzner-vm/configuration.nix
configuration.nix
so thatusers
block looks like this:# ~/my-first-flake/my-vms/my-hetzner-vm/configuration.nix # ... users.users.eugene = { isNormalUser = true; extraGroups = [ "wheel" ]; initialHashedPassword = "$y$j9T$2DyEjQxPoIjTkt8zCoWl.0$3mHxH.fqkCgu53xa0vannyu4Cue3Q7xL4CrUhMxREKC"; # Password.123 packages = [ pkgs.beam.packages.erlang_26.elixir_1_16 ]; }; # ...
- Re-build NixOS. Run:
sudo nixos-rebuild switch --flake ./my-first-flake#my-hetzner-vm
disko
TODO: it would be neat to document how to boot from the NixOS ISO and create the machine based on an online description including https://github.com/nix-community/disko specs - should be a quick way to set up bespoke 'throwaway' machines.
references:
nixos-infect
Beside the manual installation, one way to setup NixOS is to replace an existing installation, for example the latest Ubuntu image, with nixos-infect.
Cloud-init
You don't even need to log into the Ubuntu image, you can run nixos-infect from the 'could-init' as documented at https://github.com/elitak/nixos-infect/tree/master#hetzner-cloud
Manually
- Boot into the existing operating system, preferably Ubuntu or Debian
- Login as root or with root permissions
- Deploy your SSH public key for the current root user. This key will be used later for authentication into the NixOS system.
- Run following script. Replace
NIX_CHANNEL
variable with the version string you wish to install.
curl https://raw.githubusercontent.com/elitak/nixos-infect/master/nixos-infect | NIX_CHANNEL=nixos-22.11 bash -x
- Reboot into NixOS
Declarative
Network configuration
Hetzner Cloud offers both IPv4 (/32 subnet) and IPv6 (/64 subnet) connectivity to each machine. The assigned addresses can be looked up on the Hetzner Cloud Console from the "Networking" tab on the instance details. The public IPv4 address of the server can automatically obtained be via DHCP. For IPv6 you have to statically configure both address and gateway.
systemd.network.enable = true;
systemd.network.networks."30-wan" = {
matchConfig.Name = "ens3"; # either ens3 or enp1s0, check 'ip addr'
networkConfig.DHCP = "ipv4";
address = [
# replace this subnet with the one assigned to your instance
"2a01:4f8:aaaa:bbbb::1/64"
];
routes = [
{ Gateway = "fe80::1"; }
];
};
Static IPv4 configuration
The IPv4 address can also be configured statically. The trick here is, that the gateway needs to be configured with the onlink
flag, because it is not in the same subnet as your public IP address, but still very much on that same link.
systemd.network.networks."30-wan" = {
matchConfig.Name = "ens3"; # either ens3 (amd64) or enp1s0 (arm64)
networkConfig.DHCP = "no";
address = [
# replace this address with the one assigned to your instance
"A.B.C.D/32"
# replace this subnet with the one assigned to your instance
"2a01:4f8:AAAA:BBBB::1/64"
];
routes = [ {
routeConfig = { Gateway = "172.31.1.1"; GatewayOnLink = true; }; }
{ routeConfig.Gateway = "fe80::1"; }
];
};
AArch64 (CAX instance type) specifics
If the screen goes blank after selecting the boot option in the bootloader, the following snippet makes sure that GPU drivers are available in initrd, and the correct device gets used for the serial console:
boot.initrd.kernelModules = [ "virtio_gpu" ];
boot.kernelParams = [ "console=tty" ];