Add scripted host bootstrapping with directory-driven discovery

nixosConfigurations now auto-discovers hosts/<name>/ directories instead
of a hand-maintained attrset, and scripts/bootstrap-host.sh (exposed as
`nix run .#bootstrap-host`) scaffolds a new host from the template. The
script always requires an explicit --root for hardware-configuration.nix
so a live-installer run can never read the live ISO's own /etc/nixos by
accident. Also records the belated task-11.1 checkbox update for the
prior change's already-committed state.

1 files changed, 146 insertions, 0 deletions

diff --git a/scripts/bootstrap-host.sh b/scripts/bootstrap-host.sh
new file mode 100644
index 0000000..afb4e14
--- /dev/null
+++ b/scripts/bootstrap-host.sh
@@ -0,0 +1,146 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+usage() {
+  cat <<'EOF'
+Usage: bootstrap-host <hostname> --root <path> --state-version <version> [--system <system>] [--force]
+
+Scaffolds hosts/<hostname>/ from hosts/template, ready to be picked up
+automatically as nixosConfigurations.<hostname> — no flake.nix edit needed.
+Must be run from the root of the nix-config checkout.
+
+  --root <path>          Required. Where to read hardware-configuration.nix
+                          from: <path>/etc/nixos/hardware-configuration.nix.
+                          Use /mnt when running from a NixOS live/installer
+                          environment against a freshly mounted install
+                          target; use / when adopting an already-installed
+                          system. There is no default — this is always
+                          explicit so the live environment's own /etc/nixos
+                          is never read by accident.
+  --state-version <ver>  Required, e.g. 24.05. Never change this after the
+                          host's first install.
+  --system <system>      Optional. Defaults to x86_64-linux.
+  --force                Overwrite an existing hosts/<hostname> directory.
+EOF
+}
+
+hostname=""
+root=""
+state_version=""
+system="x86_64-linux"
+force=0
+
+while [ $# -gt 0 ]; do
+  case "$1" in
+  --root)
+    root="$2"
+    shift 2
+    ;;
+  --state-version)
+    state_version="$2"
+    shift 2
+    ;;
+  --system)
+    system="$2"
+    shift 2
+    ;;
+  --force)
+    force=1
+    shift
+    ;;
+  -h | --help)
+    usage
+    exit 0
+    ;;
+  -*)
+    echo "Error: unknown flag '$1'." >&2
+    usage >&2
+    exit 1
+    ;;
+  *)
+    if [ -n "$hostname" ]; then
+      echo "Error: unexpected extra argument '$1'." >&2
+      exit 1
+    fi
+    hostname="$1"
+    shift
+    ;;
+  esac
+done
+
+if [ -z "$hostname" ]; then
+  echo "Error: <hostname> is required." >&2
+  usage >&2
+  exit 1
+fi
+
+if [[ ! "$hostname" =~ ^[a-zA-Z0-9][a-zA-Z0-9-]*$ ]]; then
+  echo "Error: '$hostname' is not a valid hostname (letters, digits, hyphens; must not start with a hyphen)." >&2
+  exit 1
+fi
+
+if [ -z "$root" ]; then
+  echo "Error: --root is required (e.g. --root /mnt for a fresh install, --root / to adopt the running system)." >&2
+  exit 1
+fi
+
+if [ -z "$state_version" ]; then
+  echo "Error: --state-version is required (e.g. --state-version 24.05)." >&2
+  exit 1
+fi
+
+repo_root="$(pwd)"
+template_dir="$repo_root/hosts/template"
+host_dir="$repo_root/hosts/$hostname"
+
+if [ ! -d "$template_dir" ]; then
+  echo "Error: hosts/template not found under the current directory ($repo_root)." >&2
+  echo "Run this from the root of the nix-config checkout." >&2
+  exit 1
+fi
+
+if [ -e "$host_dir" ] && [ "$force" -ne 1 ]; then
+  echo "Error: $host_dir already exists. Pass --force to overwrite." >&2
+  exit 1
+fi
+
+rm -rf "$host_dir"
+cp -r "$template_dir" "$host_dir"
+
+sed -i.bak \
+  -e "s/networking.hostName = \"CHANGEME\";/networking.hostName = \"$hostname\";/" \
+  -e "s/system.stateVersion = \"CHANGEME\";/system.stateVersion = \"$state_version\";/" \
+  "$host_dir/configuration.nix"
+rm -f "$host_dir/configuration.nix.bak"
+
+printf '%s' "$system" >"$host_dir/system"
+
+# Always read from <root>/etc/nixos, never bare /etc/nixos — this is what
+# keeps a live-installer run from picking up the live ISO's own hardware
+# config instead of the freshly mounted install target's.
+hw_config_src="$root/etc/nixos/hardware-configuration.nix"
+
+if [ ! -f "$hw_config_src" ] && command -v nixos-generate-config >/dev/null 2>&1; then
+  echo "No hardware-configuration.nix found at $hw_config_src — generating it with 'nixos-generate-config --root $root' ..."
+  nixos-generate-config --root "$root"
+fi
+
+if [ ! -f "$hw_config_src" ]; then
+  echo "Error: could not find or generate hardware-configuration.nix at $hw_config_src." >&2
+  echo "Generate it yourself (e.g. 'nixos-generate-config --root $root') and re-run." >&2
+  exit 1
+fi
+
+cp "$hw_config_src" "$host_dir/hardware-configuration.nix"
+
+cat <<EOF
+
+Host '$hostname' scaffolded at hosts/$hostname
+
+Next steps:
+  1. Review hosts/$hostname/configuration.nix (boot loader choice, etc.)
+  2. git -C "$repo_root" add "hosts/$hostname"
+  3. Install or rebuild using <flake>#<host> syntax:
+       Fresh install:    nixos-install --root $root --flake "$repo_root#$hostname"
+       Existing system:  sudo nixos-rebuild switch --flake "$repo_root#$hostname"
+EOF