✨ Initial commit

README.md

@@ -0,0 +1,15 @@
+# hetzner-dracut-sshd
+
+🚧 **Work in progress** 🚧
+
+Post-install script for Hetzner's `installimage` that installs `dracut-sshd` to enable remote LUKS unlocking via SSH. Tested with Rocky Linux 10. It should also work with AlmaLinux 10 and possibly earlier releases, but these have not been tested.
+
+## Notes
+
+- The script assumes a setup with LVM on RAID1, but this is not a strict requirement. Other setups may require small changes to the script.
+- Replaces NetworkManager with `systemd-networkd` and installs `systemd-resolved`
+  - `systemd-networkd` is configured to use DHCP on all Ethernet interfaces
+  - Although NetworkManager would probably also work with the implicitly installed `dracut-network`, we use `systemd-networkd` here because it’s our preferred option.
+- Enables EPEL (required for `dracut-sshd` and `systemd-networkd`)
+- Installs dracut-sshd
+  - Uses the SSH keys in `/root/.ssh/authorized_keys`, as previously installed by `installimage`

post-install.sh

@@ -0,0 +1,147 @@
+#!/usr/bin/bash
+
+set -euo pipefail
+
+
+have_cmd() { command -v "$1" &>/dev/null; }
+
+enable_epel() {
+  echo "Enable CodeReady Builder repository..."
+  dnf config-manager --set-enabled crb
+
+  echo "Checking for EPEL repository..."
+  if ! dnf repolist enabled | grep -qE '^epel'; then
+    echo "EPEL repository not found — enabling it now."
+    dnf -y install epel-release || {
+      echo "Failed to install epel-release. Attempting manual enable..."
+      dnf -y install https://dl.fedoraproject.org/pub/epel/epel-release-latest-$(rpm -E %rhel).noarch.rpm
+    }
+  else
+    echo "EPEL is already enabled."
+  fi
+}
+
+install_storage_deps() {
+  dnf -y install mdadm cryptsetup lvm2
+}
+
+write_network_file() {
+  mkdir -p /etc/systemd/network
+  local f="/etc/systemd/network/20-wired.network"
+  cat > "$f" <<'EOF'
+[Match]
+Type=ether
+
+[Network]
+DHCP=yes
+EOF
+  chmod 0644 "$f"
+  echo "Wrote $f"
+}
+
+disable_networkmanager() {
+  systemctl disable NetworkManager.service || true
+  systemctl disable NetworkManager-wait-online.service || true
+  systemctl mask NetworkManager.service || true
+  echo "NetworkManager disabled and masked."
+}
+
+enable_networkd_and_resolved() {
+  dnf -y install systemd-networkd systemd-resolved
+  systemctl enable systemd-networkd.service
+  systemctl enable systemd-resolved.service
+  echo "Enabled systemd-networkd and systemd-resolved."
+}
+
+
+configure_dracut() {
+  local f="/etc/dracut.conf.d/10-raid1-luks.conf"
+  cat > "$f" <<'EOF'
+add_drivers+=" raid1 dm_crypt "
+add_dracutmodules+=" mdraid crypt lvm "
+EOF
+  chmod 0644 "$f"
+  echo "Wrote $f"
+
+  local f="/etc/dracut.conf.d/90-networkd.conf"
+  cat > "$f" <<'EOF'
+install_items+=" /etc/systemd/network/20-wired.network "
+add_dracutmodules+=" systemd-networkd "
+omit_dracutmodules+=" network-manager "
+EOF
+  chmod 0644 "$f"
+  echo "Wrote $f"
+
+  echo "Configured initrd for lvm on luks on raid1, systemd-networkd."
+}
+
+enable_dracut_sshd() {
+  dnf -y install dracut-sshd
+  echo "Enabled dracut-sshd."
+}
+
+regenerate_initrd() {
+  dracut --regenerate-all --force
+}
+
+check_initrd() {
+  local red=$(tput setaf 1)
+  local green=$(tput setaf 2)
+  local reset=$(tput sgr0)
+  local ret=0
+
+  for initrd in /boot/initramfs*; do
+    # Skip over kdump and rescue image
+    if [[ $initrd == *_64kdump.img ]] || [[ $initrd == /boot/initramfs-0-rescue* ]]; then
+      continue
+    fi
+
+    echo "== $initrd"
+
+    local tmpo=`mktemp`
+    lsinitrd $initrd &>$tmpo
+
+    for should_be in root/.ssh/authorized_keys bin/sshd usr/lib/systemd/systemd-networkd\$ etc/systemd/network/20-wired.network raid1.ko.xz dm-crypt.ko.xz usr/lib/systemd/system/cryptsetup.target bin/lvm\$ bin/mdadm\$ etc/ssh/ssh_host_ed25519_key; do
+      if grep -q "$should_be" $tmpo; then
+        echo "${green}OK: $should_be${reset}"
+      else
+        echo "${red}MISSING: $should_be${reset}"
+        ret=1
+      fi
+    done
+  done
+  return $ret
+}
+
+setup_resolv_conf() {
+  local target="/run/systemd/resolve/stub-resolv.conf"
+  [[ -e "$target" ]] || target="/run/systemd/resolve/resolv.conf"
+
+  if [[ -e /etc/resolv.conf && ! -L /etc/resolv.conf ]]; then
+    cp -a /etc/resolv.conf /etc/resolv.conf.backup.$(date +%s)
+  fi
+  ln -snf "$target" /etc/resolv.conf
+  echo "Linked /etc/resolv.conf -> $target"
+}
+
+main() {
+  enable_epel
+
+  install_storage_deps
+
+  write_network_file
+  enable_networkd_and_resolved
+  disable_networkmanager
+
+  configure_dracut
+
+  enable_dracut_sshd
+
+  regenerate_initrd
+  check_initrd
+
+  # Must be last to not break DNS before installs are finished:
+  setup_resolv_conf
+}
+
+main "$@"