create_image

#!/bin/bash

if [ "$#" != "1" ]; then
    echo \
"Usage: $0 TARGET path/to/config.conf

Builds in the TARGET directory an image defined by POSIX config file."
    exit 0
fi

if [ $EUID -gt 500 ]; then
    echo "Error: You are not root."
    exit 1
fi

# Install the packages required for this script, if needed
required_packages="debootstrap mount tar gzip"
if ! command -v $required_packages >/dev/null; then
    apt-get install -qqyy $required_packages
fi

CHROOT="$1"
CONFIG="$2"

# Source the config variables
. "$CONFIG"

if [ ! "$arch" -o \
     ! "$components" -o \
     ! "$suite" -o \
     ! "$mirror" -o \
     ! "$output_archive" ]; then
    echo "Error: $CONFIG does not define all the required variables."
    exit 1
fi

export LANG=C
export DEBIAN_FRONTEND=noninteractive DEBCONF_NONINTERACTIVE_SEEN=true DEBIAN_PRIORITY=critical  # don't ask any questions

# Install the minimum base
debootstrap --verbose --arch $arch --components $components $suite "$CHROOT" $mirror

# Set the new sources.list
cat > "$CHROOT/etc/apt/sources.list" << EOF
deb $mirror $suite ${components//,/ }
deb $mirror $suite-updates ${components//,/ }
deb $mirror $suite-security ${components//,/ }
$apt_source_lines
EOF

# Prepare the chroot for installing
mount --bind /bin/true          "$CHROOT"/usr/bin/ischroot
mount --bind /etc/resolv.conf   "$CHROOT"/etc/resolv.conf
mount --bind /proc/mounts       "$CHROOT"/etc/mtab
for fs in dev proc sys; do mount --bind /$fs "$CHROOT"/$fs ; done
echo -e "#!/bin/sh\nexit 101" > "$CHROOT"/usr/sbin/policy-rc.d && chmod a+x "$CHROOT"/usr/sbin/policy-rc.d

# Do the magic
chroot "$CHROOT" apt-get -qqyy update
chroot "$CHROOT" apt-get -yy install $packages
# Run the post-installation scripts
if [ "$scripts" ]; then
    mkdir -p "$CHROOT/tmp/$scripts"
    mount --bind "$scripts" "$CHROOT/tmp/$scripts"
    chroot "$CHROOT" run-parts --verbose --exit-on-error "$scripts"
    umount "$CHROOT"/tmp
fi

# Unprepare the chroot
rm "$CHROOT"/usr/sbin/policy-rc.d
for fs in dev proc sys; do umount "$CHROOT"/$fs ; done
umount "$CHROOT"/etc/mtab
umount "$CHROOT"/etc/resolv.conf
umount "$CHROOT"/usr/bin/ischroot

# Clean the directories
rm -r "$CHROOT"/{tmp,var/tmp,dev,proc,sys,media,mnt,run}/*

# Compress the chroot directory
tar --exclude-backups -C "$CHROOT" -cf- . | gzip --fast --stdout > "$output_archive"