Add all-in-one Ubuntu Server 26.04 + kiosk install ISO builder

iso/build-iso.sh remasters the official 26.04.x live-server ISO (downloaded
and checksum-verified, or --iso PATH) with xorriso, replaying its BIOS/UEFI
boot records unchanged. It adds:

- /autoinstall.yaml: Subiquity autoinstall that answers locale/keyboard/SSH
  and by default leaves only network, storage and identity interactive
  (--username/--auto-storage/--auto-network/--no-confirm/--fully-automatic
  make those automatic too). late-commands copy the repo (a clone of the
  current HEAD) to /opt/ubuntu-based-kiosk and enable a first-boot service.
- iso/firstboot/kiosk-firstboot(.service): on first boot, takes tty1, waits
  for cloud-init and internet, copies the repo to the admin user's home and
  runs ./install.sh as that user with temporary passwordless sudo (removed
  on every exit path). Failed/interrupted installs re-run next boot.

install.sh hooks for this:
- KIOSK_UNATTENDED=1 makes ask_yes_no take each prompt's default and skips
  the Core Settings menu (--unattended).
- KIOSK_PROVISION_DONE_MARKER is touched by provision_finish before the
  reboot prompt, so the caller can tell a finished install from an
  interrupted one.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Cjz8a58eB5P9sUweqd3NHm
This commit is contained in:
Claude
2026-10-03 01:18:54 +00:00
parent 08b33ef823
commit aee6b779eb
7 changed files with 648 additions and 1 deletions
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#!/bin/bash
################################################################################
# iso/build-iso.sh - Build an Ubuntu Server 26.04 install ISO with the
# kiosk built in, so there's no separate "install Ubuntu, then clone and
# run ./install.sh" step.
#
# What the ISO does:
# 1. Boots the stock Ubuntu Server installer (Subiquity), driven by an
# autoinstall.yaml at the root of the ISO. By default it still asks
# for network, disk and your admin username/password - everything
# else (language, keyboard, SSH server, snaps...) is answered for
# you. Flags below make any of those automatic too.
# 2. At the end of the install (autoinstall late-commands), copies this
# repo to /opt/ubuntu-based-kiosk on the new system and enables a
# one-shot first-boot service (firstboot/kiosk-firstboot.service).
# 3. On the first boot of the installed system, that service takes over
# tty1 and runs ./install.sh as your admin user from
# ~/ubuntu-based-kiosk - interactively by default (same prompts as a
# manual install), or with --unattended taking every default and
# rebooting straight into the kiosk. Configure sites afterwards via
# the Web UI (http://<ip>:8090) or ./install.sh.
#
# Nothing in the original ISO is changed except /boot/grub/grub.cfg
# (menu title, plus the `autoinstall` kernel argument with --no-confirm);
# boot records (BIOS + UEFI) are replayed from the original as-is.
#
# Requirements (on the build machine, any recent Ubuntu/Debian):
# sudo apt install xorriso curl git openssl
#
# Usage:
# iso/build-iso.sh [options]
#
# --iso PATH Use this Ubuntu Server ISO instead of downloading.
# --release VER Ubuntu release to download (default: 26.04 - picks
# the newest 26.04.x live-server-amd64 point release).
# --output PATH Output ISO (default: iso/build/ubuntu-<ver>-kiosk-amd64.iso)
#
# Installed system:
# --username NAME Admin username (the account you SSH in with and run
# ./install.sh as - must not be "kiosk"). Giving this
# makes the installer's identity screen automatic.
# --password PASS Admin password (prompted for if --username is given
# without it). Stored only as a SHA-512 crypt hash.
# --hostname NAME Hostname (default: kiosk).
# --realname NAME Full name for the admin account (default: Kiosk Admin).
# --ssh-key FILE Add this public key file to the admin user's
# authorized_keys.
# --locale LOCALE Default: en_US.UTF-8
# --keyboard LAYOUT Default: us
# --auto-storage Don't ask about disks: wipe the largest disk and use
# all of it (LVM). DESTROYS DATA on that disk.
# --auto-network Don't show the network screen (DHCP on wired
# interfaces). Leave this off if you need WiFi.
# --no-confirm Don't ask "Continue with autoinstall?" at boot.
# --fully-automatic Shorthand for --auto-storage --auto-network
# --no-confirm --unattended; needs --username.
# Booting this ISO will wipe a disk with NO questions.
#
# Kiosk install on first boot:
# --unattended Run install.sh with all defaults, no prompts
# (skips the Core Settings menu), then reboot.
# --repo-url URL git remote recorded in the copied repo, used by
# Advanced -> Upgrade (default: this checkout's
# origin, else the upstream GitHub repo).
#
# The repo copied onto the ISO is a clone of this checkout's current HEAD
# (committed changes only - uncommitted edits are NOT included).
################################################################################
set -euo pipefail
SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
REPO_ROOT="$(cd "$SCRIPT_DIR/.." && pwd)"
BUILD_DIR="$SCRIPT_DIR/build"
DEFAULT_REPO_URL="https://github.com/outis1one/ubuntu-based-kiosk.git"
SRC_ISO=""
RELEASE="26.04"
OUTPUT=""
ADMIN_USER=""
ADMIN_PASS=""
HOSTNAME_="kiosk"
REALNAME="Kiosk Admin"
SSH_KEY_FILE=""
LOCALE="en_US.UTF-8"
KEYBOARD="us"
AUTO_STORAGE=0
AUTO_NETWORK=0
NO_CONFIRM=0
UNATTENDED=0
REPO_URL=""
die() { echo "ERROR: $*" >&2; exit 1; }
info() { echo "==> $*"; }
usage() {
sed -n '/^# Usage:/,/^################/p' "$0" | sed '$d; s/^# \{0,1\}//'
exit "${1:-0}"
}
while [[ $# -gt 0 ]]; do
case "$1" in
--iso) SRC_ISO="$2"; shift 2 ;;
--release) RELEASE="$2"; shift 2 ;;
--output) OUTPUT="$2"; shift 2 ;;
--username) ADMIN_USER="$2"; shift 2 ;;
--password) ADMIN_PASS="$2"; shift 2 ;;
--hostname) HOSTNAME_="$2"; shift 2 ;;
--realname) REALNAME="$2"; shift 2 ;;
--ssh-key) SSH_KEY_FILE="$2"; shift 2 ;;
--locale) LOCALE="$2"; shift 2 ;;
--keyboard) KEYBOARD="$2"; shift 2 ;;
--auto-storage) AUTO_STORAGE=1; shift ;;
--auto-network) AUTO_NETWORK=1; shift ;;
--no-confirm) NO_CONFIRM=1; shift ;;
--unattended) UNATTENDED=1; shift ;;
--fully-automatic) AUTO_STORAGE=1; AUTO_NETWORK=1; NO_CONFIRM=1; UNATTENDED=1; shift ;;
--repo-url) REPO_URL="$2"; shift 2 ;;
-h|--help) usage 0 ;;
*) echo "Unknown option: $1" >&2; usage 1 ;;
esac
done
################################################################################
# Validate
################################################################################
for cmd in xorriso curl git openssl sha256sum; do
command -v "$cmd" &>/dev/null || die "'$cmd' not found - install it: sudo apt install xorriso curl git openssl"
done
if [[ -n "$ADMIN_USER" ]]; then
[[ "$ADMIN_USER" =~ ^[a-z_][a-z0-9_-]{0,31}$ ]] || die "invalid username: $ADMIN_USER"
[[ "$ADMIN_USER" != "kiosk" && "$ADMIN_USER" != "root" ]] \
|| die "username '$ADMIN_USER' is reserved (install.sh creates its own 'kiosk' user)"
if [[ -z "$ADMIN_PASS" ]]; then
read -r -s -p "Password for $ADMIN_USER: " ADMIN_PASS; echo
read -r -s -p "Confirm password: " pass2; echo
[[ "$ADMIN_PASS" == "$pass2" ]] || die "passwords don't match"
[[ -n "$ADMIN_PASS" ]] || die "empty password"
fi
elif [[ -n "$ADMIN_PASS" ]]; then
die "--password needs --username"
fi
if (( AUTO_STORAGE && AUTO_NETWORK && NO_CONFIRM )) && [[ -z "$ADMIN_USER" ]]; then
die "--fully-automatic (or all of --auto-storage --auto-network --no-confirm) needs --username"
fi
[[ "$HOSTNAME_" =~ ^[a-zA-Z0-9]([a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?$ ]] || die "invalid hostname: $HOSTNAME_"
[[ -z "$SSH_KEY_FILE" || -r "$SSH_KEY_FILE" ]] || die "can't read --ssh-key file: $SSH_KEY_FILE"
if [[ -z "$REPO_URL" ]]; then
REPO_URL="$(git -C "$REPO_ROOT" remote get-url origin 2>/dev/null || true)"
# Local proxies/mirrors and ssh remotes aren't reachable from a kiosk.
[[ "$REPO_URL" == https://github.com/* ]] || REPO_URL="$DEFAULT_REPO_URL"
fi
mkdir -p "$BUILD_DIR"
WORK="$(mktemp -d "$BUILD_DIR/work.XXXXXX")"
trap 'rm -rf "$WORK"' EXIT
################################################################################
# Source ISO - download and verify unless one was given
################################################################################
if [[ -z "$SRC_ISO" ]]; then
base="https://releases.ubuntu.com/$RELEASE"
info "Looking up the latest Ubuntu $RELEASE live-server ISO..."
sums="$(curl -fsSL "$base/SHA256SUMS")" || die "couldn't fetch $base/SHA256SUMS"
iso_name="$(grep -oE "ubuntu-${RELEASE//./\\.}(\.[0-9]+)?-live-server-amd64\.iso" <<<"$sums" | sort -V | tail -1)"
[[ -n "$iso_name" ]] || die "no live-server-amd64 ISO listed in $base/SHA256SUMS"
expected="$(grep -F "*$iso_name" <<<"$sums" | awk '{print $1}')"
mkdir -p "$BUILD_DIR/cache"
SRC_ISO="$BUILD_DIR/cache/$iso_name"
if [[ -f "$SRC_ISO" ]] && echo "$expected $SRC_ISO" | sha256sum -c --status; then
info "Using cached $iso_name"
else
info "Downloading $iso_name (~3 GB)..."
curl -fL --retry 5 -C - -o "$SRC_ISO" "$base/$iso_name" \
|| curl -fL --retry 5 -o "$SRC_ISO" "$base/$iso_name"
info "Verifying checksum..."
echo "$expected $SRC_ISO" | sha256sum -c --status \
|| { rm -f "$SRC_ISO"; die "checksum mismatch for $iso_name - deleted, re-run to retry"; }
fi
fi
[[ -f "$SRC_ISO" ]] || die "ISO not found: $SRC_ISO"
if [[ -z "$OUTPUT" ]]; then
src_base="$(basename "$SRC_ISO" .iso)"
OUTPUT="$BUILD_DIR/${src_base/-live-server/-kiosk}.iso"
[[ "$OUTPUT" != "$BUILD_DIR/$src_base.iso" ]] || OUTPUT="$BUILD_DIR/${src_base}-kiosk.iso"
fi
################################################################################
# Stage the repo + first-boot files that go on the ISO under /kiosk
################################################################################
info "Staging repo ($(git -C "$REPO_ROOT" rev-parse --abbrev-ref HEAD) @ $(git -C "$REPO_ROOT" rev-parse --short HEAD))..."
if [[ -n "$(git -C "$REPO_ROOT" status --porcelain)" ]]; then
echo " WARNING: uncommitted changes in $REPO_ROOT are NOT included - commit them first if you need them."
fi
mkdir -p "$WORK/kiosk/firstboot"
git clone --quiet --depth 1 --no-local \
--branch "$(git -C "$REPO_ROOT" rev-parse --abbrev-ref HEAD)" \
"file://$REPO_ROOT" "$WORK/kiosk/ubuntu-based-kiosk"
git -C "$WORK/kiosk/ubuntu-based-kiosk" remote set-url origin "$REPO_URL"
install -m 755 "$SCRIPT_DIR/firstboot/kiosk-firstboot" "$WORK/kiosk/firstboot/"
install -m 644 "$SCRIPT_DIR/firstboot/kiosk-firstboot.service" "$WORK/kiosk/firstboot/"
cat > "$WORK/kiosk/firstboot/kiosk-firstboot.conf" <<EOF
# Read by /usr/local/sbin/kiosk-firstboot. Written by iso/build-iso.sh.
# 1 = take every install.sh default and reboot into the kiosk; 0 = interactive.
KIOSK_UNATTENDED=$UNATTENDED
EOF
################################################################################
# autoinstall.yaml
################################################################################
# Single-quoted YAML scalar.
yq() { printf "'%s'" "${1//\'/\'\'}"; }
interactive=()
(( AUTO_NETWORK )) || interactive+=(network)
(( AUTO_STORAGE )) || interactive+=(storage)
[[ -n "$ADMIN_USER" ]] || interactive+=(identity)
{
echo "#cloud-config"
echo "# Generated by iso/build-iso.sh - see that file for what this does."
echo "autoinstall:"
echo " version: 1"
if (( ${#interactive[@]} )); then
echo " interactive-sections:"
for s in "${interactive[@]}"; do echo " - $s"; done
fi
echo " locale: $(yq "$LOCALE")"
echo " keyboard:"
echo " layout: $(yq "$KEYBOARD")"
# Pre-selected answer for the storage screen when it's interactive;
# the whole answer when --auto-storage.
echo " storage:"
echo " layout:"
echo " name: lvm"
echo " sizing-policy: all"
if [[ -n "$ADMIN_USER" ]]; then
echo " identity:"
echo " hostname: $(yq "$HOSTNAME_")"
echo " realname: $(yq "$REALNAME")"
echo " username: $(yq "$ADMIN_USER")"
echo " password: $(yq "$(openssl passwd -6 -stdin <<<"$ADMIN_PASS")")"
fi
echo " ssh:"
echo " install-server: true"
echo " allow-pw: true"
if [[ -n "$SSH_KEY_FILE" ]]; then
echo " authorized-keys:"
while IFS= read -r key; do
[[ -z "$key" || "$key" == \#* ]] && continue
echo " - $(yq "$key")"
done < "$SSH_KEY_FILE"
fi
cat <<'EOF'
late-commands:
- mkdir -p /target/opt /target/usr/local/sbin /target/var/lib/kiosk-firstboot
- cp -a /cdrom/kiosk/ubuntu-based-kiosk /target/opt/ubuntu-based-kiosk
- chmod -R u+w /target/opt/ubuntu-based-kiosk
- install -m 755 /cdrom/kiosk/firstboot/kiosk-firstboot /target/usr/local/sbin/kiosk-firstboot
- install -m 644 /cdrom/kiosk/firstboot/kiosk-firstboot.service /target/etc/systemd/system/kiosk-firstboot.service
- install -m 644 /cdrom/kiosk/firstboot/kiosk-firstboot.conf /target/etc/kiosk-firstboot.conf
- touch /target/var/lib/kiosk-firstboot/pending
- curtin in-target --target=/target -- systemctl enable kiosk-firstboot.service
EOF
} > "$WORK/autoinstall.yaml"
################################################################################
# grub.cfg - same file serves BIOS and UEFI boot on the server ISO
################################################################################
xorriso -osirrox on -indev "$SRC_ISO" -extract /boot/grub/grub.cfg "$WORK/grub.cfg" 2>/dev/null \
|| die "couldn't read /boot/grub/grub.cfg from $SRC_ISO - is it an Ubuntu Server ISO?"
chmod u+w "$WORK/grub.cfg"
grep -q '/casper/vmlinuz' "$WORK/grub.cfg" || die "unexpected grub.cfg layout in $SRC_ISO"
sed -i 's/Try or Install Ubuntu Server/Install Ubuntu Based Kiosk/' "$WORK/grub.cfg"
if (( NO_CONFIRM )); then
sed -i -E '/linux[[:space:]]+\/casper\/vmlinuz/ s/[[:space:]]+---/ autoinstall ---/' "$WORK/grub.cfg"
fi
################################################################################
# Write the new ISO
################################################################################
info "Writing $OUTPUT..."
rm -f "$OUTPUT"
xorriso -indev "$SRC_ISO" -outdev "$OUTPUT" \
-map "$WORK/autoinstall.yaml" /autoinstall.yaml \
-map "$WORK/kiosk" /kiosk \
-map "$WORK/grub.cfg" /boot/grub/grub.cfg \
-boot_image any replay \
-padding included \
> "$WORK/xorriso.log" 2>&1 \
|| { cat "$WORK/xorriso.log" >&2; rm -f "$OUTPUT"; die "xorriso failed"; }
echo
info "Done: $OUTPUT ($(du -h "$OUTPUT" | cut -f1))"
echo
echo "Installer asks for : ${interactive[*]:-nothing}$( (( NO_CONFIRM )) || echo " (plus a 'Continue with autoinstall?' confirmation)")"
echo "Admin user : ${ADMIN_USER:-chosen during install}"
echo "First boot : $( (( UNATTENDED )) && echo "unattended install.sh, then reboots into the kiosk" || echo "interactive install.sh on the console")"
echo
echo "Write it to a USB stick (replace /dev/sdX - this erases it):"
echo " sudo dd if='$OUTPUT' of=/dev/sdX bs=4M status=progress oflag=sync"
if (( AUTO_STORAGE && NO_CONFIRM )); then
echo
echo "WARNING: this ISO wipes the target's largest disk without asking. Label the stick."
fi