Create a new Debian `chroot` environment in Alpine Linux

chroot-create.sh

#!/bin/sh

if [[ $(id -u) -eq 0 ]]; then
  echo "This script cannot be run as root, root access will be requested through \`sudo\`"
  exit 1
fi


user="$USER"
group="$user"


path_working="$PWD"
path_debian="$path_working/debian"
path_slash="$path_debian/slash"

slash="$path_slash"
debian="$path_debian"


read -p "Creating \"$slash\" with user $user:$group, continue (y/n)? " choice
case "$choice" in 
  y|Y ) echo "Confirmed" ;;
  * )   exit 1           ;;
esac


mkdir -p "$path_debian"
mkdir -p "$path_slash"


sudo apk add debootstrap perl
sudo debootstrap --arch i386 buster "$slash" "http://deb.debian.org/debian"
sudo apk del debootstrap perl


sudo rm "$slash/etc/resolv.conf" "$slash/etc/hosts"
sudo ln "/etc/resolv.conf"       "$slash/etc/resolv.conf"
sudo ln "/etc/hosts"             "$slash/etc/hosts"


file_mount="$debian/mount.sh"
file_shell="$debian/shell.sh"

cat > "$file_mount" << EOF
#!/bin/sh

if [[ \$(id -u) -ne 0 ]]; then
  echo "Permission denied, please run as root"
  exit 1
fi

runfile="/run/debian-mounted"
if [[ -f \$runfile ]]; then
  echo "Already mounted"
  exit 1
fi
touch \$runfile

slash='$slash'

mount --bind /dev     "\$slash/dev"
mount --bind /dev/pts "\$slash/dev/pts"
mount --bind /proc    "\$slash/proc"

mount --bind /sys "\$slash/sys"
mount --bind /run "\$slash/run"

EOF
sudo chmod +x "$file_mount"

cat > "$file_shell" << EOF
#!/bin/sh

if [[ \$(id -u) -ne 0 ]]; then
  echo "Permission denied, please run as root"
  exit 1
fi

chroot '$slash' /usr/bin/su -s /usr/bin/bash -g '$group' -l '$user'

EOF
sudo chmod +x "$file_shell"


sudo sh "$file_mount"

sudo chroot "$slash" /usr/bin/bash << EOF

cat > /usr/sbin/policy-rc.d << EOM
#!/bin/sh
exit 101

EOM
chmod +x /usr/sbin/policy-rc.d

printf "deb http://deb.debian.org/debian buster main contrib non-free" > /etc/apt/sources.list

apt update
apt upgrade
apt install sudo nano wget

exit

EOF


echo "===[ Setting up chroot user ]==================================================="
sudo chroot "$slash" /usr/sbin/adduser "$user"
echo "================================================================================"

sudo chroot "$slash" /usr/bin/bash << EOF

usermod -aG sudo lua
printf '\n$user ALL=(ALL) ALL\n' >> /etc/sudoers

exit

EOF

chroot-remove.sh

#!/bin/sh

path_working="$PWD"
path_debian="$path_working/debian"
path_slash="$path_debian/slash"

slash="$path_slash"
debian="$path_debian"


read -p "Destroying \"$slash\" and parent \"$debian\", continue (y/n)? " choice
case "$choice" in 
  y|Y ) echo "Confirmed" ;;
  * )   exit 1           ;;
esac


sudo umount -l "$slash/dev/pts"

sudo umount -l "$slash/dev"     && \
sudo umount -l "$slash/proc"    && \
sudo umount -l "$slash/sys"     && \
sudo umount -l "$slash/run"     || exit 1


sudo rm -rf "$slash"
sudo rm -rf "$debian"

sudo rm -rf "/etc/init.d/debian-mount"
sudo rm -rf "/etc/init.d/debian-chroot-mount"