nix-auto-installer/common.nix

{ pkgs, lib, ... }:

{
  networking.useDHCP = lib.mkDefault true;

  time.timeZone = "Australia/Brisbane";

  # Without this, the installer only ever sees cache.nixos.org, which
  # doesn't carry sops-install-secrets (it's built straight from the
  # sops-nix flake's own Go source, not part of nixpkgs) — every install
  # would otherwise compile it from scratch, which is what ran an 8GB LXC
  # container's disk out of space. Push a built copy to nix-cache once
  # (from a machine with real disk headroom) and every future install,
  # of any type, fetches instead of rebuilding.
  nix.settings = {
    substituters = [
      "http://nix-cache"
      "https://cache.nixos.org/"
    ];
    trusted-public-keys = [
      "cache.local-1:usoWYanY3Kpq2+kDIS2nhWoLZiRxanmdysdzqCFBHW4="
      "cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY="
    ];
  };

  environment.systemPackages = with pkgs; [
    git
    curl
    jq
    parted
    e2fsprogs
    btrfs-progs
    util-linux
    disko
  ];

  programs.git = {
    enable = true;

    config = {
      credential.helper = "store --file=/etc/git-credentials";
    };
  };

  environment.etc."git-credentials".text =
    "https://beatzaplenty:294be99829703536e02fdeed893137f1d8d96b76@gitea.lan.ddnsgeek.com";

  # Run the installer on first login. Previously this copied an /etc file
  # into the nixos user's ~/.bash_profile via an activation script that
  # got dropped in a refactor (and only ever worked for that one user
  # anyway) — loginShellInit is NixOS's native hook for this, applies to
  # any user's login shell (root included), and needs no home-directory
  # file-copying/chown.
  programs.bash.loginShellInit = ''
    if [ -n "$PS1" ] && [ ! -e "$HOME/.auto_install_ran" ]; then
      sudo /etc/auto-install.sh
      touch "$HOME/.auto_install_ran"
    fi
  '';


  services.openssh.enable = true;

  services.openssh.settings = {
    PermitRootLogin = "yes";
    PasswordAuthentication = true;
  };


  users.users.root = {
    hashedPassword =
      "$6$Kwv9KAyvcurAViQF$H4.u3feqGE7lVoNgkFXhE3n2Pmo//9JYDTCz8ifrVHBxPjwa1xMby7tEZ8Bpt5MXs9Rkx6/YbZWxs5CpH0s/70";
  };


  users.users.nixos = {
    isNormalUser = true;

    extraGroups = [
      "wheel"
    ];

    shell = pkgs.bashInteractive;

    hashedPassword =
      "$6$Kwv9KAyvcurAViQF$H4.u3feqGE7lVoNgkFXhE3n2Pmo//9JYDTCz8ifrVHBxPjwa1xMby7tEZ8Bpt5MXs9Rkx6/YbZWxs5CpH0s/70";

    openssh.authorizedKeys.keys = [
      "ssh-rsa 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 wayne@stream"
    ];
  };


  system.stateVersion = "26.05";

    # Write auto-install script to /root
  environment.etc."auto-install.sh".text = ''
    #!/run/current-system/sw/bin/bash
    set -eux

    set -euo pipefail

export FLAKE_BASE_URL="git+https://gitea.lan.ddnsgeek.com/beatzaplenty/nixos.git"

echo "Fetching available NixOS hosts from flake..."
mapfile -t options < <(
  nix eval --json --no-use-registries --no-accept-flake-config --extra-experimental-features "flakes nix-command" \
    "''${FLAKE_BASE_URL}#nixosConfigurations" \
    --apply builtins.attrNames \
  | jq -r '.[]'
)

if [[ ''${#options[@]} -eq 0 ]]; then
  echo "ERROR: No NixOS hosts found in ''${FLAKE_BASE_URL}#nixosConfigurations" >&2
  exit 1
fi

echo "Choose the flake profile to install:"
select choice in "''${options[@]}"; do
  if [[ -n "$choice" ]]; then
    echo "You selected: $choice"
    break
  else
    echo "Invalid selection. Try again."
  fi
done

echo "Starting install with flake: ''${FLAKE_BASE_URL}#''${choice}"

# Optional: confirm before proceeding
read -rp "Proceed with installation? (y/N): " confirm
if [[ ! "$confirm" =~ ^[Yy]$ ]]; then
  echo "Aborted."
  exit 1
fi
    
if nix eval --refresh --json  --extra-experimental-features "flakes nix-command" "''${FLAKE_BASE_URL}#nixosConfigurations.''${choice}.config.disko.devices.disk.main.device" >/dev/null 2>&1; then
    disko --mode destroy,format,mount \
        --flake "''${FLAKE_BASE_URL}#''${choice}" --yes
else
    # No raw disk to partition — true for every LXC container, which has
    # no block device visible from inside it, only its already-mounted
    # root filesystem. nixos-install defaults to installing into /mnt; if
    # nothing points /mnt at the real root, the new system gets built and
    # written to a disconnected empty directory, never actually becomes
    # bootable, and the container silently keeps running this installer
    # environment forever. Bind-mount / onto /mnt so the install actually
    # lands on the filesystem this container boots from.
    echo "Selected host has no Disko configuration — installing in place via bind mount."
    mount --bind / /mnt
fi

# sops-nix derives this host's decryption key from its own SSH host key
# at *activation* time, which runs before systemd would otherwise
# generate one on first boot. Without pre-seeding it here, secrets
# (including the login password) fail to decrypt on first boot.
# Generate the key + register it with `nixos`'s sops-nix setup ahead of
# time (see nix-auto-installer/scripts/prepare-host-key.sh), then scp it
# to /root/host-keys/ on this machine before continuing.
mkdir -p /root/host-keys
if [[ -f "/root/host-keys/''${choice}_ssh_host_ed25519_key" ]]; then
    echo "Found pre-seeded SSH host key for ''${choice}, installing to target..."
    install -D -m 0600 "/root/host-keys/''${choice}_ssh_host_ed25519_key" /mnt/etc/ssh/ssh_host_ed25519_key
    install -D -m 0644 "/root/host-keys/''${choice}_ssh_host_ed25519_key.pub" /mnt/etc/ssh/ssh_host_ed25519_key.pub
else
    echo "WARNING: no pre-seeded host key found at /root/host-keys/''${choice}_ssh_host_ed25519_key"
    echo "sops-nix secrets (including the login password) will NOT decrypt on first boot."
    echo "Run scripts/prepare-host-key.sh for host ''${choice} on your admin workstation first,"
    echo "then scp the result here, if this host needs sops-nix secrets."
    read -rp "Continue without a pre-seeded key anyway? (y/N): " skip_key
    if [[ ! "$skip_key" =~ ^[Yy]$ ]]; then
        echo "Aborted."
        exit 1
    fi
fi

mkdir -p /mnt/install-tmp
export TMPDIR=/mnt/install-tmp

nixos-install \
    --flake "''${FLAKE_BASE_URL}#''${choice}" \
    --no-root-password


    rm -rf /mnt/install-tmp
    sleep 10
    reboot
  '';

    environment.etc."auto-install.sh".mode = "0755";
}