#!/bin/bash

#
# template script for generating Arch linux container for LXC
#

#
# lxc: linux Container library

# Authors:
# Alexander Vladimirov <idkfa@vlan1.ru>

# This library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License as published by the Free Software Foundation; either
# version 2.1 of the License, or (at your option) any later version.

# This library is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
# Lesser General Public License for more details.

# You should have received a copy of the GNU Lesser General Public
# License along with this library; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA

# defaults
arch=$(arch)
cache=/var/cache/lxc/arch/${arch}
lxc_network_type="veth"
lxc_network_link="br0"
default_path=/var/lib/lxc
default_rc_locale="en-US.UTF-8"
default_rc_timezone="UTC"
host_mirror="http://mirrors.kernel.org/archlinux/\$repo/os/$arch"

# sort of minimal package set
base_packages=(
    "filesystem"
    "initscripts"
    "coreutils"
    "module-init-tools"
    "procps"
    "psmisc"
    "pacman"
    "bash"
    "syslog-ng"
    "cronie"
    "iproute2"
    "iputils"
    "inetutils"
    "dhcpcd"
    "dnsutils"
    "nano"
    "grep"
    "less"
    "gawk"
    "sed"
    "tar"
    "wget"
    "gzip"
    "which"
)
declare -a additional_packages

[ -f /etc/arch-release ] && is_arch=true

# find and extract parameter value from given config file
# ${1} - file to read parameter from
# ${2} - parameter name
# ${result} - result value on success
function read_parameter_value {
    [ -f ${1} ] && [ "${2}" ] || return 1
    local pattern="^[[:space:]]*${2}[[:space:]]*=[[:space:]]*"
    local str=$(grep "${pattern}" "${1}")
    local str=${str/#$(grep -o "${pattern}" "${1}")/}
    result=${str//\"/}
    return 0
}

# split comma-separated string into an array
# ${1} - string to split
# ${2} - separator (default is ",")
# ${result} - result value on success
function split_string {
    local ifs=${IFS}
    IFS="${2:-,}"
    read -a result < <(echo "${1}")
    IFS=${ifs}
    return 0
}

# Arch-specific preconfiguration for container
function configure_arch {
    # read locale and timezone defaults from system rc.conf if running on Arch
    if [ "${is_arch}" ]; then
        read_parameter_value "/etc/rc.conf" "LOCALE"
        rc_locale=${result:-${default_rc_locale}}
        read_parameter_value "/etc/rc.conf" "TIMEZONE"
        rc_timezone=${result:-${default_rc_timezone}}
    else
        rc_locale=${default_rc_locale}
        rc_timezone=${default_rc_timezone}
    fi

    echo "Setting up rc.conf"
    cat > "${rootfs_path}/etc/rc.conf" << EOF
# /etc/rc.conf - Main Configuration for Arch Linux
LOCALE="${rc_locale}"
DAEMON_LOCALE="no"
HARDWARECLOCK="local"
TIMEZONE="${rc_timezone}"
KEYMAP=us
CONSOLEFONT=
CONSOLEMAP=
USECOLOR="yes"
MODULES=()
HOSTNAME="${name}"
interface=eth0
address=
netmask=
broadcast=
gateway=
DAEMONS=(syslog-ng crond network)
EOF

    if [ -e "${rootfs_path}/etc/locale.gen" ]; then
        sed -i 's@^#\(en_US\.UTF-8\)@\1@' "${rootfs_path}/etc/locale.gen"
        if [ ! "${rc_locale}" = "en_US.UTF-8" ]; then
            echo "${rc_locale} ${rc_locale##*.}" >> "${rootfs_path}/etc/locale.gen"
        fi
        chroot "${rootfs_path}" locale-gen
    fi
    cp "${rootfs_path}/usr/share/zoneinfo/${rc_timezone}" \
       "${rootfs_path}/etc/localtime"

    echo "Setting up rc.sysinit"
    cat > "${rootfs_path}/etc/rc.sysinit.lxc" << EOF
#!/bin/bash
. /etc/rc.conf
. /etc/rc.d/functions

echo "starting Arch Linux"
rm -f \$(find /var/run -name '*pid')
rm -f /run/daemons/*
rm -f /var/lock/subsys/*
rm -f /etc/mtab
touch /etc/mtab
run_hook sysinit_end
EOF

    echo "Setting up rc.shutdown"
    cat > "${rootfs_path}/etc/rc.shutdown.lxc" << EOF
#!/bin/bash
. /etc/rc.conf
. /etc/rc.d/functions
stty onlcr
run_hook shutdown_start
[[ -x /etc/rc.local.shutdown ]] && /etc/rc.local.shutdown
stop_all_daemons
run_hook shutdown_prekillall
kill_all
run_hook shutdown_postkillall
[[ \${TIMEZONE} ]] && cp --remove-destination "/usr/share/zoneinfo/\${TIMEZONE}" /etc/localtime
halt -w
umount -a -r -t nodevtmpfs,notmpfs,nosysfs,noproc,nodevpts -O no_netdev
run_hook shutdown_postumount
run_hook shutdown_poweroff
if [[ \${RUNLEVEL} = 0 ]]; then
    poweroff -d -f -i
else
    reboot -d -f -i
fi
# vim: set ts=2 sw=2 noet:
EOF
    chmod 755 "${rootfs_path}/etc/rc.shutdown.lxc" "${rootfs_path}/etc/rc.sysinit.lxc"

    echo "Setting up inittab"
    cat > "${rootfs_path}/etc/inittab" << EOF
id:3:initdefault:
rc::sysinit:/etc/rc.sysinit.lxc
rs:S1:wait:/etc/rc.single
rm:2345:wait:/etc/rc.multi
rh:06:wait:/etc/rc.shutdown.lxc
su:S:wait:/sbin/sulogin -p
c1:2345:respawn:/sbin/agetty -8 38400 tty1 linux
EOF

    echo "Setting up hosts"
    cat > "${rootfs_path}/etc/hosts" << EOF
127.0.0.1   localhost.localdomain   localhost ${name}
::1     localhost.localdomain   localhost
EOF

    echo "Setting up nameserver"
    grep nameserver /etc/resolv.conf > "${rootfs_path}/etc/resolv.conf"

    echo "Setting up device nodes"
    mkdir -m 755 "${rootfs_path}/dev/pts"
    mkdir -m 1777 "${rootfs_path}/dev/shm"
    mknod -m 666 "${rootfs_path}/dev/null" c 1 3
    mknod -m 666 "${rootfs_path}/dev/full" c 1 7
    mknod -m 666 "${rootfs_path}/dev/random" c 1 8
    mknod -m 666 "${rootfs_path}/dev/urandom" c 1 9
    mknod -m 666 "${rootfs_path}/dev/tty0" c 4 0
    mknod -m 666 "${rootfs_path}/dev/tty1" c 4 1
    mknod -m 666 "${rootfs_path}/dev/tty2" c 4 2
    mknod -m 666 "${rootfs_path}/dev/tty3" c 4 3
    mknod -m 666 "${rootfs_path}/dev/tty4" c 4 4
    mknod -m 600 "${rootfs_path}/dev/initctl" p
    mknod -m 666 "${rootfs_path}/dev/tty" c 5 0
    mknod -m 666 "${rootfs_path}/dev/console" c 5 1
    mknod -m 666 "${rootfs_path}/dev/ptmx" c 5 2

    return 0
}

# write container configuration files
function copy_configuration {
    mkdir -p "${config_path}"
    grep -q "^lxc.rootfs" "${config_path}/config" 2>/dev/null || echo "lxc.rootfs=${rootfs_path}" >> "${config_path}/config"
    cat > "${config_path}/config" << EOF
lxc.utsname=${name}
lxc.tty=4
lxc.pts=1024
lxc.mount=${config_path}/fstab
#networking
lxc.network.type=${lxc_network_type}
lxc.network.flags=up
lxc.network.link=${lxc_network_link}
lxc.network.name=eth0
lxc.network.mtu=1500
#cgroups
lxc.cgroup.devices.deny = a
# /dev/null and zero
lxc.cgroup.devices.allow = c 1:3 rwm
lxc.cgroup.devices.allow = c 1:5 rwm
# consoles
lxc.cgroup.devices.allow = c 5:1 rwm
lxc.cgroup.devices.allow = c 5:0 rwm
lxc.cgroup.devices.allow = c 4:0 rwm
lxc.cgroup.devices.allow = c 4:1 rwm
# /dev/{,u}random
lxc.cgroup.devices.allow = c 1:9 rwm
lxc.cgroup.devices.allow = c 1:8 rwm
# /dev/pts
lxc.cgroup.devices.allow = c 136:* rwm
lxc.cgroup.devices.allow = c 5:2 rwm
# rtc
lxc.cgroup.devices.allow = c 254:0 rwm
EOF

    cat > "${config_path}/fstab" << EOF
none ${rootfs_path}/dev/pts devpts defaults 0 0
none ${rootfs_path}/proc proc nodev,noexec,nosuid 0 0
none ${rootfs_path}/sys sysfs defaults 0 0
none ${rootfs_path}/dev/shm tmpfs defaults 0 0
EOF

    if [ ${?} -ne 0 ]; then
        echo "Failed to configure container"
        return 1
    fi

    return 0
}

# lock chroot and mount subdirectories before installing container
function mount_chroot {
    echo "mounting chroot"
    umask 0022
    [ -e "${rootfs_path}/sys" ] || mkdir "${rootfs_path}/sys"
    mount -t sysfs sysfs "${rootfs_path}/sys"
    [ -e "${rootfs_path}/proc" ] || mkdir "${rootfs_path}/proc"
    mount -t proc proc "${rootfs_path}/proc"
    [ -e "${rootfs_path}/dev" ] || mkdir "${rootfs_path}/dev"
    mount -t tmpfs dev "${rootfs_path}/dev" -o mode=0755,size=10M,nosuid
    mknod -m 666 "${rootfs_path}/dev/null" c 1 3
    mknod -m 666 "${rootfs_path}/dev/zero" c 1 5
    mknod -m 600 "${rootfs_path}/dev/console" c 5 1
    mknod -m 644 "${rootfs_path}/dev/random" c 1 8
    mknod -m 644 "${rootfs_path}/dev/urandom" c 1 9
    mknod -m 666 "${rootfs_path}/dev/tty" c 5 0
    mknod -m 666 "${rootfs_path}/dev/tty0" c 4 0
    mknod -m 666 "${rootfs_path}/dev/full" c 1 7
    ln -s /proc/kcore "${rootfs_path}/dev/core"
    ln -s /proc/self/fd "${rootfs_path}/dev/fd"
    ln -s /proc/self/fd/0 "${rootfs_path}/dev/stdin"
    ln -s /proc/self/fd/1 "${rootfs_path}/dev/stdout"
    ln -s /proc/self/fd/2 "${rootfs_path}/dev/stderr"
    [ -e "${rootfs_path}/dev/shm" ] || mkdir "${rootfs_path}/dev/shm"
    mount -t tmpfs shm "${rootfs_path}/dev/shm" -o nodev,nosuid,size=128M
    [ -e "${rootfs_path}/dev/pts" ] || mkdir "${rootfs_path}/dev/pts"
    mount -t devpts devpts "${rootfs_path}/dev/pts" -o newinstance,ptmxmode=666
    ln -s pts/ptmx "${rootfs_path}/dev/ptmx"
    [ -e "${cache_dir}" ] || mkdir -p "${cache_dir}"
    [ -e "${rootfs_path}/${cache_dir}" ] || mkdir -p "${rootfs_path}/${cache_dir}"
    mount -o bind "${cache_dir}" "${rootfs_path}/${cache_dir}"
    if [ -n "${host_mirror_path}" ]; then
        [ -e "${rootfs_path}/${host_mirror_path}" ] || mkdir -p "${rootfs_path}/${host_mirror_path}"
        mount -o bind "${host_mirror_path}" "${rootfs_path}/${host_mirror_path}"
        mount -o remount,ro,bind "${host_mirror_path}" "${rootfs_path}/${host_mirror_path}"
    fi
    trap 'umount_chroot' EXIT INT QUIT TERM HUP
}

function umount_chroot {
    if [ -z "${umount_done}" ]; then
        echo "unmounting chroot"
        umount "${rootfs_path}/proc"
        umount "${rootfs_path}/sys"
        umount "${rootfs_path}/dev/pts"
        umount "${rootfs_path}/dev/shm"
        umount "${rootfs_path}/dev"
        umount "${rootfs_path}/${cache_dir}"
        [ -n "${host_mirror_path}" ] && umount "${rootfs_path}/${host_mirror_path}"
        umount_done=1
    fi
}

# install packages within container chroot
function install_arch {
    pacman_config=$(mktemp)

    cat <<EOF > "${pacman_config}"
[options]
HoldPkg      = pacman glibc
SyncFirst    = pacman
Architecture = auto
#IgnorePkg    = udev
[core]
Include = /etc/pacman.d/mirrorlist
Server = ${host_mirror}
[extra]
Include = /etc/pacman.d/mirrorlist
Server = ${host_mirror}
[community]
Include = /etc/pacman.d/mirrorlist
Server = ${host_mirror}
EOF

    mkdir -p "${rootfs_path}/var/lib/pacman/sync"
    mkdir -p "${rootfs_path}/etc"

    if echo "${host_mirror}" | grep -q 'file://'; then
        host_mirror_path=$(echo "${host_mirror}" | sed -E 's#file://(/.*)/\$repo/os/\$arch#\1#g')
    fi
    cache_dir=$( (grep -m 1 '^CacheDir' "${pacman_config}" || echo 'CacheDir = /var/cache/pacman/pkg') | sed 's/CacheDir\s*=\s*//')
    mount_chroot
    params="--root ${rootfs_path} --config=${pacman_config} --noconfirm"
    if ! pacman -Sydd ${params} --dbonly udev; then
        echo "Failed to preinstall udev package record"
        return 1
    fi
    if ! pacman -S ${params} ${base_packages[@]}; then
        echo "Failed to install container packages"
        return 1
    fi
    [ -d "${rootfs_path}/lib/modules" ] && ldconfig -r "${rootfs_path}"
    mv "${pacman_config}" "${rootfs_path}/etc/pacman.conf"
    umount_chroot
    return 0
}

usage()
{
    cat <<EOF
usage:
    ${1} -n|--name=<container_name>
        [-P|--packages=<pkg1,pkg2,...>] [-p|--path=<path>] [-h|--help]
Mandatory args:
  -n,--name         container name, used to as an identifier for that container from now on
Optional args:
  -p,--path         path to where the container rootfs will be created, defaults to /var/lib/lxc. The container config will go under /var/lib/lxc in that case
  -P,--packages     preinstall additional packages, comma-separated list
  -h,--help         print this help
EOF
    return 0
}

options=$(getopt -o hp:P:n:cm: -l help,path:,packages:,name:,clean,mirror: -- "${@}")
if [ ${?} -ne 0 ]; then
    usage $(basename ${0})
    exit 1
fi
eval set -- "${options}"

while true
do
    case "${1}" in
    -h|--help)      usage ${0} && exit 0;;
    -p|--path)      path=${2}; shift 2;;
    -n|--name)      name=${2}; shift 2;;
    -P|--packages)  additional_packages=${2}; shift 2;;
    -m|--mirror)    host_mirror=${2}; shift 2;;
    --)             shift 1; break ;;
    *)              break ;;
    esac
done

if [ -z "${name}" ]; then
    echo "missing required 'name' parameter"
    exit 1
fi

type pacman >/dev/null 2>&1
if [ ${?} -ne 0 ]; then
    echo "'pacman' command is missing, refer to wiki.archlinux.org for information about installing pacman"
    exit 1
fi

if [ -z "${path}" ]; then
    path="${default_path}/${name}"
fi

if [ "${EUID}" != "0" ]; then
    echo "This script should be run as 'root'"
    exit 1
fi

rootfs_path="${path}/rootfs"
# check for 'lxc.rootfs' passed in through default config by lxc-create
if grep -q '^lxc.rootfs' $path/config 2>/dev/null ; then
    rootfs_path=`grep 'lxc.rootfs =' $path/config | awk -F= '{ print $2 }'`
fi
config_path="${default_path}/${name}"

revert()
{
    echo "Interrupted, so cleaning up"
    lxc-destroy -n "${name}"
    # maybe was interrupted before copy config
    rm -rf "${path}/${name}"
    rm -rf "${default_path}/${name}"
    exit 1
}

trap revert SIGHUP SIGINT SIGTERM

copy_configuration
if [ ${?} -ne 0 ]; then
    echo "failed write configuration file"
    rm -rf "${config_path}"
    exit 1
fi

if [ ${#additional_packages[@]} -gt 0 ]; then
    split_string ${additional_packages}
    base_packages+=(${result[@]})
fi

install_arch
if [ ${?} -ne 0 ]; then
    echo "failed to install Arch linux"
    rm -rf "${config_path}" "${path}"
    exit 1
fi

configure_arch
if [ ${?} -ne 0 ]; then
    echo "failed to configure Arch linux for a container"
    rm -rf "${config_path}" "${path}"
    exit 1
fi

echo "container rootfs and config created"