#!/bin/bash -e
#----------
# Interactive installation steps for debian bookworm from GRML using debootstrap

# Design decisions
# - Fokus on a small and simple setup
# - Use systemd whereever possible (network, ntp, cron, journald logging)
# - Minimal number of packages
# - One disk
# - Schema VM: single ext4 partition, cloud kernel, grub-pc
# - Schema Physical Server partitions for efi, os and luks data container
# - Random root and admin user password generation
# - Swap-file as safety net
# - SSH on port 50101 limited to the admin user

# Usage
# Boot grml or run from an existing debian/ubuntu installation
# grml: passwd root; grml-network; Start ssh
# git clone https://git.in-ulm.de/ulpeters/bootstrap.git
# cp config.sh.template config.sh                    # copy template
# config-get-netconf-eth0.sh                         # get running grml network config
# vi config.sh                                       # update installation variables
# bootstrap-bookworm.sh install                      # start installation
# !! Note down the admin passwords and reboot
# sudo /installer/bootstrap-bookworm.sh postinstall  # run postinstall in the new system

# Default variables
mnt="/mnt/root"                     # mountpoint for the new root filesystem
hostname="somehost.example.com"
kernelPkg="linux-image-cloud-amd64" # alternative: linux-image-amd64
partition="mbr-single"              # mbr-single or efi-crypt
disk="/dev/vda"                     # find with: lsblk --list
disk0=$disk"p1"                     # efi partion, only relevant if partion="efi-crypt"
disk1=$disk"1"                      # "p1" for nbd or p2 for efi-crypt
netDev="eth0"                       # find with: ip link
netAddress="203.0.113.66/24"        # "" blank for dhcp on e*
netGateway="203.0.113.1"            # likely first IP within the network
netBroadcast="203.0.113.255"        # last IP within the network
netDNS1="192.0.2.10"
netDNS2="198.51.100.10"
netNTP="pool.ntp.org"
pwdAdmin=""                         # "" blank for auto-generation
pwdRoot=""                          # "" blank for auto-generation
debootstrap="native"                # docker, to run in docker container
extraPackages="qemu-guest-agent"    # additional packages to install, e.g. cryptsetup

# Overwrite default variables from config file
[ -f ./config.sh ] && source config.sh


# Setup network in grml based on config.sh
grmlnetwork(){
ip link show # list interfaces
ip addr add $netAddress dev $netDev
ip link set $netDev up
ip route add default via $netGateway
echo nameserver $netDNS1 >> /etc/resolv.conf
echo nameserver $netDNS2 >> /etc/resolv.conf
}


install(){
#----------
# Prepare disk

echo "🗑️ Wipe existing partition table to supress warnings from parted"
dd if=/dev/zero of=$disk bs=512 count=34

# Parition disks -- pkg: parted
# Prepare partition tables and partitions
# -parted --script does not accept blanks in partition names

# Prepare disks with a single mbr partition
if [ "$partition" = "mbr-single" ]
then
  echo "📐 Prepare mbr partition table with a single partition"
  parted $disk --script \
  mklabel msdos \
  mkpart primary ext4 512M 100% toggle 1 boot \
  print
fi

# Prepare disks with gpt/efi
if [ "$partition" = "efi-crypt" ]
then
  echo "📐 Prepare gpt partition table with following layout:"
  echo "- 301 MB partition for EFI                          --> p1"
  echo "- 50  GB root partition for the OS (includes /boot) --> p2"
  echo "- Remaining disk left to create a luks container    --> p3"
  parted $disk --script                              \
  mklabel gpt                                        \
  mkpart EFI_system_partition  fat32    1MiB 301MiB  \
  set  1 esp  on                                     \
  set  1 boot on                                     \
  align-check optimal 1                              \
  mkpart Linux_system_parition  ext4  301MiB   50GiB \
  align-check optimal 2                              \
  mkpart Data_partion                  50GiB   100%  \
  align-check optimal 3                              \
  unit MiB                                           \
  print
  
  # Inform OS about partition table change
  partprobe $disk && sleep 1
  
  # Format EFI partition -- pkg: dosfstools e2fsprogs
  mkfs.fat  -v -F 32 -n EFIBOOT $disk0 && fsck $disk0
fi

# Format OS disk -- pkg: e2fsprogs
mkfs.ext4 -v -F               $disk1 && fsck $disk1

# Prepare mount points and mount
mkdir -p $mnt
mount $disk1 $mnt

# Create swapfile
swapfile=$mnt/swapfile
dd if=/dev/zero of=$swapfile bs=1M count=1024 status=progress # create 1GB file
chmod 600 $swapfile # restric permissions
mkswap $swapfile    # format file

#----------
# Bootstrap -- pkg: debootstrap
# Remark: Debootstrap does not install recommands!!
case "$debootstrap" in
   native)   debootstrap --variant=minbase --arch=amd64 bookworm $mnt http://ftp2.de.debian.org/debian/
             ;;
   # Alternatively bootstrap from a docker container, e.g. if no recent debootstrap is available
   docker)   docker run -it --rm --cap-add=SYS_CHROOT --name debootstrap \
                        -v $mnt:$mnt -e mnt=$mnt debian /bin/sh -c \
                        "apt-get update && apt-get install --yes debootstrap \
                        && debootstrap --variant=minbase --arch=amd64 bookworm \
                        $mnt http://ftp2.de.debian.org/debian/"
             ;;
esac


# Configure disk mounts
# Or get UUID from blkid...
[ "$partition" = "efi-crypt" ] && \
echo "$disk0        /boot/efi/                vfat rw 0 0" >> $mnt/etc/fstab
echo "$disk1        /                     ext4 rw       0 0"    >> $mnt/etc/fstab
echo "/swapfile        none                  swap defaults 0 0" >> $mnt/etc/fstab

# Configure sources.list
cat >$mnt/etc/apt/sources.list <<EOL
deb http://deb.debian.org/debian bookworm main non-free-firmware
# deb-src http://deb.debian.org/debian bookworm main non-free-firmware
deb http://deb.debian.org/debian-security/ bookworm-security main non-free-firmware
# deb-src http://deb.debian.org/debian-security/ bookworm-security main non-free-firmware
deb http://deb.debian.org/debian bookworm-updates main non-free-firmware
# deb-src http://deb.debian.org/debian bookworm-updates main non-free-firmware
EOL

# Configure hostname
echo "127.0.0.1       $hostname" >> $mnt/etc/hosts
echo "$hostname"                  > $mnt/etc/hostname

#----------
# Prepare chroot
mount -o bind /dev $mnt/dev
mount -o bind /dev/pts $mnt/dev/pts
mount -t sysfs /sys $mnt/sys
mount -t proc /proc $mnt/proc
cp /proc/mounts $mnt/etc/mtab
cp /etc/resolv.conf $mnt/etc/resolv.conf
mkdir -p $mnt/installer
cp $(dirname `realpath $0`)/*.sh $mnt/installer

# Run script in chroot
chroot $mnt /bin/bash /installer/bootstrap-bookworm.sh install2

# Install bootloader
$0 bootloader
}


#----------
# Function executed within chroot
install2(){
source /installer/config.sh 
# Select grub version based on partition table
case "$partition" in
   mbr-single)   grubPkg="grub-pc"   ;;
   efi-crypt)    grubPkg="grub-efi"  ;;
esac

# Install basic system
apt-get update
export DEBIAN_FRONTEND=noninteractive
apt-get install --yes \
  apt-utils dialog file msmtp-mta \
  systemd-sysv locales tzdata haveged \
  $kernelPkg $grubPkg \
  iproute2 netbase \
  ssh sudo molly-guard \
  less vim-tiny bash-completion pwgen lsof \
  dnsutils iputils-ping pciutils curl wget bzip2 \
  $extraPackages

# Upgrade and clean up
apt-get upgrade --yes
apt-get autoremove --yes
apt-get clean --yes

# Setup users and passwords
[ -z $pwdAdmin ] && pwdAdmin=`pwgen --capitalize --numerals --ambiguous 12 1`
useradd admin --create-home --shell /bin/bash
echo "admin:$pwdAdmin" | chpasswd
usermod -a -G sudo admin
echo -e "\e[1;33;4;44m🔐 Password for the user admin: $pwdAdmin\e[0m"
pass=`pwgen --capitalize --numerals --ambiguous 12 1`
[ -z $pwdRoot ] && pwdRoot=`pwgen --capitalize --numerals --ambiguous 12 1`
echo "root:$pwdRoot"   | chpasswd
echo -e "\e[1;33;4;44m🔐 Password for the user root: $pwdRoot\e[0m"

# Harden SSHD
sed -i -e 's/#Port 22/Port 50101/g' /etc/ssh/sshd_config
sed -i -e 's/#PubkeyAuthentication yes/PubkeyAuthentication yes/g' /etc/ssh/sshd_config
# https://infosec.mozilla.org/guidelines/openssh.html

# Allow admin to sudo without password
echo AllowUsers admin >> /etc/ssh/sshd_config
echo "admin ALL=(ALL) NOPASSWD:ALL" > /etc/sudoers.d/admin

## Configure network using systemd
if [ -z $netAddress ]
then
## Network OPTION 1 - DHCP
cat >/etc/systemd/network/20-wired.network <<EOL
[Match]
Name=e*

[Network]
DHCP=ipv4
IPv6PrivacyExtensions=false
IPv6AcceptRA=false
NTP=$netNTP
EOL

else
## Network OPTION 2 - static
cat >/etc/systemd/network/20-wired.network <<EOL
[Match]
Name=$netDev

[Network]
Address=$netAddress
Gateway=$netGateway
Broadcast=$netBroadcast
DNS=$netDNS1
DNS=$netDNS2
NTP=$netNTP
EOL
fi

## Setup systemd resolver
apt-get install --yes systemd-resolved
echo -e "\n# Disable local name resolution"  >> /etc/systemd/resolved.conf
echo "LLMNR=no" >> /etc/systemd/resolved.conf
echo "MulticastDNS=no" >> /etc/systemd/resolved.conf
systemctl enable systemd-networkd
systemctl enable systemd-resolved

# Limit journald logging to 1 month, 1 GB in total and split files per week
mkdir -p /etc/systemd/journald.conf.d/
cat >/etc/systemd/journald.conf.d/retention.conf <<EOL
MaxRetentionSec=1month
SystemMaxUse=1G
MaxFileSec=1week
EOL

# Show errors in motd
rm /etc/motd   
cat >/etc/update-motd.d/15-boot-errors<<EOL
#!/bin/sh
echo
journalctl --boot --priority=3 --no-pager
EOL
chmod 755 /etc/update-motd.d/15-boot-errors

# Setup keyboard layout
cat >/etc/default/keyboard <<EOL
XKBMODEL="pc105"
XKBLAYOUT="de"
XKBVARIANT="nodeadkeys"
XKBOPTIONS=""
BACKSPACE="guess"
EOL

# Leave chroot
exit
}


bootloader(){
# Install grub
echo "$partition partition"
case "$partition" in
   mbr-single) 
     chroot $mnt /bin/bash -c "grub-install $disk && update-grub"
     ;;
   efi-crypt)
     chroot $mnt /bin/bash -c \
     "mkdir -p /boot/efi && mount /boot/efi \
      && grub-install --target=x86_64-efi --efi-directory=/boot/efi \
                      --bootloader-id=grub && update-grub \
      && umount /boot/efi"
     ;;
esac
}


unmount(){
# Unmount if mounted
# Remark: Function called unmount and not umount to avoid collision with the command
! mountpoint -q $mnt/proc     || umount -v $mnt/proc
! mountpoint -q $mnt/sys      || umount -v $mnt/sys
! mountpoint -q $mnt/dev/pts  || umount -v $mnt/dev/pts
! mountpoint -q $mnt/dev      || umount -v $mnt/dev
! mountpoint -q $mnt          || umount -v $mnt
# Delete mount-point if empty and not mounted
[ -d $mnt ] && [ -z "$(ls -A $mnt)" ] && ! mountpoint -q $mnt \
&& rm -R $mnt && echo "🗑️ mountpoint $mnt deleted" 
}


postinstall(){
####----REBOOT into the new system, so we'll have dbus running
localectl set-locale LANG=de_DE.UTF-8         # Default for LC_* variables not  set. 
localectl set-locale LC_MESSAGES=en_US.UTF-8  # System messages. 
#localectl set-locale LC_RESPONSE=en_US.UTF-8  # How responses (such as Yes and No) appear
update-locale
timedatectl set-timezone Europe/Berlin
}


# Switch to functions...
case $1 in
  grmlnetwork)
    echo Setup network in grml
    grmlnetwork
    ;;
  install)
    echo "Stage 1: Start installation"
    install
    ;;
  install2)
    echo "Stage 2: Start installation in chroot"
    install2
    ;;
  bootloader)
    echo "Stage 3: Install bootloader and unmount chroot"
    bootloader
    unmount
    echo "👍 We're done and can reboot now"
    ;;
  postinstall)
    echo "Stage 4: Start post-installation in live system"
    postinstall
    ;;
  unmount)
    echo "Unmount chroot, e.g. in case installation fails"
    unmount
    ;;
  *)
    echo "Valid functions are: grmlnetwork, install, postinstall and unmount" >&2
    ;;
esac