name: hosts description: Add and configure new NixOS host machines

Hosts

Required Files

Each host needs these files in hosts/<type>/<hostname>/:

Using the Helper Script

The easiest way to create a new host:

# Usage: new-host.sh <host-type> <host-name>
nix run .#new-host -- server mynewserver
nix run .#new-host -- desktop mynewdesktop

This script:

1. Creates the host directory
2. Generates SSH keypair
3. Creates minimal default.nix
4. Updates .sops.yaml with the new host's age key
5. Creates encrypted secrets.yaml

Manual Host Creation

1. Create directory structure

mkdir -p hosts/server/myserver

2. Create default.nix

# hosts/server/myserver/default.nix
{ modulesPath, ... }:
{
  imports = [
    # For LXC containers:
    "${modulesPath}/virtualisation/proxmox-lxc.nix"
    # Or for physical machines:
    # ./hardware.nix
  ];

  host.device.isHeadless = true;  # For servers

  # Host-specific configuration
}

3. Create hardware.nix (physical machines)

# hosts/desktop/mydesktop/hardware.nix
{ inputs, ... }:
{
  imports = [
    inputs.nixos-hardware.nixosModules.common-cpu-amd
    inputs.nixos-hardware.nixosModules.common-pc-ssd
  ];

  boot.loader = {
    systemd-boot.enable = true;
    efi.canTouchEfiVariables = true;
  };

  fileSystems."/" = {
    device = "/dev/disk/by-label/nixos";
    fsType = "ext4";
  };
}

4. Generate SSH key and setup secrets

# Generate key
ssh-keygen -t ed25519 -f /tmp/ssh_host_ed25519_key -N ""
cp /tmp/ssh_host_ed25519_key.pub hosts/server/myserver/

# Get age key from SSH key
ssh-to-age < hosts/server/myserver/ssh_host_ed25519_key.pub
# Add this to .sops.yaml

# Create secrets file
sops hosts/server/myserver/secrets.yaml
# Add: SSH_PRIVATE_KEY: <content of private key>

Auto-Discovery

Hosts are automatically discovered - no manual flake registration needed. The system:

1. Scans hosts/ for subdirectories
2. Filters out shared/ and secrets.yaml
3. Registers each as a nixosConfiguration

Device Types

Shared Configurations

Configurations are applied in order:

1. hosts/shared/global/ - All hosts
2. hosts/<type>/shared/ - All hosts of this type
3. hosts/<type>/<hostname>/ - This specific host

Hardware Acceleration

For CUDA or ROCm support, add the host to flake/nixos/flake-module.nix:

accelerationHosts = {
  cuda = [ "nixmi" "mynewhost" ];
  rocm = [ "myamdhost" ];
};

Binding Users to Hosts

Create home/<username>/<hostname>.nix to assign a user to a host. The system auto-detects this and includes the user's home-manager configuration.

See also: docs/Creating-Hosts.md