#!/bin/bash

#
# template script for generating ubuntu container for LXC
#
# This script consolidates and extends the existing lxc ubuntu scripts
#

# Copyright © 2011 Serge Hallyn <serge.hallyn@canonical.com>
# Copyright © 2010 Wilhelm Meier
# Author: Wilhelm Meier <wilhelm.meier@fh-kl.de>
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License version 2, as
# published by the Free Software Foundation.

# This program 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 General Public License for more details.

# You should have received a copy of the GNU General Public License along
# with this program; if not, write to the Free Software Foundation, Inc.,
# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
#

set -e

if [ -r /etc/default/lxc ]; then
    . /etc/default/lxc
fi

configure_ubuntu()
{
    rootfs=$1
    hostname=$2
    release=$3

   # configure the network using the dhcp
    cat <<EOF > $rootfs/etc/network/interfaces
# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).

# The loopback network interface
auto lo
iface lo inet loopback

auto eth0
iface eth0 inet dhcp
EOF

    # set the hostname
    cat <<EOF > $rootfs/etc/hostname
$hostname
EOF
    # set minimal hosts
    cat <<EOF > $rootfs/etc/hosts
127.0.0.1   localhost
127.0.1.1   $hostname

# The following lines are desirable for IPv6 capable hosts
::1     ip6-localhost ip6-loopback
fe00::0 ip6-localnet
ff00::0 ip6-mcastprefix
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters
EOF

    if [ ! -f $rootfs/etc/init/container-detect.conf ]; then
        # suppress log level output for udev
        sed -i "s/=\"err\"/=0/" $rootfs/etc/udev/udev.conf

        # remove jobs for consoles 5 and 6 since we only create 4 consoles in
        # this template
        rm -f $rootfs/etc/init/tty{5,6}.conf
    fi

    if [ -z "$bindhome" ]; then
        chroot $rootfs useradd --create-home -s /bin/bash ubuntu
        echo "ubuntu:ubuntu" | chroot $rootfs chpasswd
    fi

    return 0
}

# finish setting up the user in the container by injecting ssh key and
# adding sudo group membership.
# passed-in user is either 'ubuntu' or the user to bind in from host.
finalize_user()
{
    user=$1

    sudo_version=$(chroot $rootfs dpkg-query -W -f='${Version}' sudo)

    if chroot $rootfs dpkg --compare-versions $sudo_version gt "1.8.3p1-1"; then
        groups="sudo"
    else
        groups="sudo admin"
    fi

    for group in $groups; do
        chroot $rootfs groupadd --system $group >/dev/null 2>&1 || true
        chroot $rootfs adduser ${user} $group >/dev/null 2>&1 || true
    done

    if [ -n "$auth_key" -a -f "$auth_key" ]; then
        u_path="/home/${user}/.ssh"
        root_u_path="$rootfs/$u_path"

        mkdir -p $root_u_path
        cp $auth_key "$root_u_path/authorized_keys"
        chroot $rootfs chown -R ${user}: "$u_path"

        echo "Inserted SSH public key from $auth_key into /home/${user}/.ssh/authorized_keys"
    fi
    return 0
}

write_sourceslist()
{
    # $1 => path to the rootfs
    # $2 => architecture we want to add
    # $3 => whether to use the multi-arch syntax or not

    case $2 in
      amd64|i386)
            MIRROR=${MIRROR:-http://archive.ubuntu.com/ubuntu}
            SECURITY_MIRROR=${SECURITY_MIRROR:-http://security.ubuntu.com/ubuntu}
            ;;
      *)
            MIRROR=${MIRROR:-http://ports.ubuntu.com/ubuntu-ports}
            SECURITY_MIRROR=${SECURITY_MIRROR:-http://ports.ubuntu.com/ubuntu-ports}
            ;;
    esac
    if [ -n "$3" ]; then
        cat >> "$1/etc/apt/sources.list" << EOF
deb [arch=$2] $MIRROR ${release} main restricted universe multiverse
deb [arch=$2] $MIRROR ${release}-updates main restricted universe multiverse
deb [arch=$2] $SECURITY_MIRROR ${release}-security main restricted universe multiverse
EOF
    else
        cat >> "$1/etc/apt/sources.list" << EOF
deb $MIRROR ${release} main restricted universe multiverse
deb $MIRROR ${release}-updates main restricted universe multiverse
deb $SECURITY_MIRROR ${release}-security main restricted universe multiverse
EOF
    fi
}

download_ubuntu()
{
    cache=$1
    arch=$2
    release=$3

    packages=vim,ssh
    echo "installing packages: $packages"

    # check the mini ubuntu was not already downloaded
    mkdir -p "$cache/partial-$arch"
    if [ $? -ne 0 ]; then
        echo "Failed to create '$cache/partial-$arch' directory"
        return 1
    fi

    # download a mini ubuntu into a cache
    echo "Downloading ubuntu $release minimal ..."
    if [ -n "$(which qemu-debootstrap)" ]; then
        qemu-debootstrap --verbose --components=main,universe --arch=$arch --include=$packages $release $cache/partial-$arch $MIRROR
    else
        debootstrap --verbose --components=main,universe --arch=$arch --include=$packages $release $cache/partial-$arch $MIRROR
    fi

    if [ $? -ne 0 ]; then
        echo "Failed to download the rootfs, aborting."
            return 1
    fi

    # Serge isn't sure whether we should avoid doing this when
    # $release == `distro-info -d`
    echo "Installing updates"
    > $cache/partial-$arch/etc/apt/sources.list
    write_sourceslist $cache/partial-$arch/ $arch

    chroot "$1/partial-${arch}" apt-get update
    if [ $? -ne 0 ]; then
        echo "Failed to update the apt cache"
        return 1
    fi
    cat > "$1/partial-${arch}"/usr/sbin/policy-rc.d << EOF
#!/bin/sh
exit 101
EOF
    chmod +x "$1/partial-${arch}"/usr/sbin/policy-rc.d

    lxc-unshare -s MOUNT -- chroot "$1/partial-${arch}" apt-get dist-upgrade -y
    ret=$?
    rm -f "$1/partial-${arch}"/usr/sbin/policy-rc.d

    if [ $ret -ne 0 ]; then
        echo "Failed to upgrade the cache"
        return 1
    fi

    mv "$1/partial-$arch" "$1/rootfs-$arch"
    echo "Download complete"
    return 0
}

copy_ubuntu()
{
    cache=$1
    arch=$2
    rootfs=$3

    # make a local copy of the miniubuntu
    echo "Copying rootfs to $rootfs ..."
    mkdir -p $rootfs
    rsync -a $cache/rootfs-$arch/ $rootfs/ || return 1
    return 0
}

install_ubuntu()
{
    rootfs=$1
    release=$2
    flushcache=$3
    cache="/var/cache/lxc/$release"
    mkdir -p /var/lock/subsys/

    (
        flock -x 200
        if [ $? -ne 0 ]; then
            echo "Cache repository is busy."
            return 1
        fi


        if [ $flushcache -eq 1 ]; then
            echo "Flushing cache..."
            rm -rf "$cache/partial-$arch"
            rm -rf "$cache/rootfs-$arch"
        fi

        echo "Checking cache download in $cache/rootfs-$arch ... "
        if [ ! -e "$cache/rootfs-$arch" ]; then
            download_ubuntu $cache $arch $release
            if [ $? -ne 0 ]; then
                echo "Failed to download 'ubuntu $release base'"
                return 1
            fi
        fi

        echo "Copy $cache/rootfs-$arch to $rootfs ... "
        copy_ubuntu $cache $arch $rootfs
        if [ $? -ne 0 ]; then
            echo "Failed to copy rootfs"
            return 1
        fi

        return 0

    ) 200>/var/lock/subsys/lxc

    return $?
}

copy_configuration()
{
    path=$1
    rootfs=$2
    name=$3
    arch=$4
    release=$5

    if [ $arch = "i386" ]; then
        arch="i686"
    fi

    ttydir=""
    if [ -f $rootfs/etc/init/container-detect.conf ]; then
        ttydir=" lxc"
    fi

    # if there is exactly one veth network entry, make sure it has an
    # associated hwaddr.
    nics=`grep -e '^lxc\.network\.type[ \t]*=[ \t]*veth' $path/config | wc -l`
    if [ $nics -eq 1 ]; then
        grep -q "^lxc.network.hwaddr" $path/config || cat <<EOF >> $path/config
lxc.network.hwaddr = 00:16:3e:$(openssl rand -hex 3| sed 's/\(..\)/\1:/g; s/.$//')
EOF
    fi

    cat <<EOF >> $path/config
lxc.utsname = $name

lxc.devttydir =$ttydir
lxc.tty = 4
lxc.pts = 1024
lxc.rootfs = $rootfs
lxc.mount  = $path/fstab
lxc.arch = $arch
lxc.cap.drop = sys_module mac_admin mac_override
lxc.pivotdir = lxc_putold

# uncomment the next line to run the container unconfined:
#lxc.aa_profile = unconfined

lxc.cgroup.devices.deny = a
# Allow any mknod (but not using the node)
lxc.cgroup.devices.allow = c *:* m
lxc.cgroup.devices.allow = b *:* m
# /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
lxc.cgroup.devices.allow = c 136:* rwm
lxc.cgroup.devices.allow = c 5:2 rwm
# rtc
lxc.cgroup.devices.allow = c 254:0 rwm
#fuse
lxc.cgroup.devices.allow = c 10:229 rwm
#tun
lxc.cgroup.devices.allow = c 10:200 rwm
#full
lxc.cgroup.devices.allow = c 1:7 rwm
#hpet
lxc.cgroup.devices.allow = c 10:228 rwm
#kvm
lxc.cgroup.devices.allow = c 10:232 rwm
EOF

    cat <<EOF > $path/fstab
proc            proc         proc    nodev,noexec,nosuid 0 0
sysfs           sys          sysfs defaults  0 0
EOF

    if [ $? -ne 0 ]; then
        echo "Failed to add configuration"
        return 1
    fi

    return 0
}

trim()
{
    rootfs=$1
    release=$2

    # provide the lxc service
    cat <<EOF > $rootfs/etc/init/lxc.conf
# fake some events needed for correct startup other services

description     "Container Upstart"

start on startup

script
        rm -rf /var/run/*.pid
        rm -rf /var/run/network/*
        /sbin/initctl emit stopped JOB=udevtrigger --no-wait
        /sbin/initctl emit started JOB=udev --no-wait
end script
EOF

    # fix buggus runlevel with sshd
    cat <<EOF > $rootfs/etc/init/ssh.conf
# ssh - OpenBSD Secure Shell server
#
# The OpenSSH server provides secure shell access to the system.

description "OpenSSH server"

start on filesystem
stop on runlevel [!2345]

expect fork
respawn
respawn limit 10 5
umask 022
# replaces SSHD_OOM_ADJUST in /etc/default/ssh
oom never

pre-start script
    test -x /usr/sbin/sshd || { stop; exit 0; }
    test -e /etc/ssh/sshd_not_to_be_run && { stop; exit 0; }
    test -c /dev/null || { stop; exit 0; }

    mkdir -p -m0755 /var/run/sshd
end script

# if you used to set SSHD_OPTS in /etc/default/ssh, you can change the
# 'exec' line here instead
exec /usr/sbin/sshd
EOF

    cat <<EOF > $rootfs/etc/init/console.conf
# console - getty
#
# This service maintains a console on tty1 from the point the system is
# started until it is shut down again.

start on stopped rc RUNLEVEL=[2345]
stop on runlevel [!2345]

respawn
exec /sbin/getty -8 38400 /dev/console
EOF

    cat <<EOF > $rootfs/lib/init/fstab
# /lib/init/fstab: cleared out for bare-bones lxc
EOF

    # reconfigure some services
    if [ -z "$LANG" ]; then
        chroot $rootfs locale-gen en_US.UTF-8
        chroot $rootfs update-locale LANG=en_US.UTF-8
    else
        chroot $rootfs locale-gen $LANG
        chroot $rootfs update-locale LANG=$LANG
    fi

    # remove pointless services in a container
    chroot $rootfs /usr/sbin/update-rc.d -f ondemand remove

    chroot $rootfs /bin/bash -c 'cd /etc/init; for f in $(ls u*.conf); do mv $f $f.orig; done'
    chroot $rootfs /bin/bash -c 'cd /etc/init; for f in $(ls tty[2-9].conf); do mv $f $f.orig; done'
    chroot $rootfs /bin/bash -c 'cd /etc/init; for f in $(ls plymouth*.conf); do mv $f $f.orig; done'
    chroot $rootfs /bin/bash -c 'cd /etc/init; for f in $(ls hwclock*.conf); do mv $f $f.orig; done'
    chroot $rootfs /bin/bash -c 'cd /etc/init; for f in $(ls module*.conf); do mv $f $f.orig; done'

    # if this isn't lucid, then we need to twiddle the network upstart bits :(
    if [ $release != "lucid" ]; then
        sed -i 's/^.*emission handled.*$/echo Emitting lo/' $rootfs/etc/network/if-up.d/upstart
    fi
}

post_process()
{
    rootfs=$1
    release=$2
    trim_container=$3

    if [ $trim_container -eq 1 ]; then
        trim $rootfs $release
    elif [ ! -f $rootfs/etc/init/container-detect.conf ]; then
        # Make sure we have a working resolv.conf
        cresolvonf="${rootfs}/etc/resolv.conf"
        mv $cresolvonf ${cresolvonf}.lxcbak
        cat /etc/resolv.conf > ${cresolvonf}

        # for lucid, if not trimming, then add the ubuntu-virt
        # ppa and install lxcguest
        if [ $release = "lucid" ]; then
            chroot $rootfs apt-get install --force-yes -y python-software-properties
            chroot $rootfs add-apt-repository ppa:ubuntu-virt/ppa
        fi

        chroot $rootfs apt-get update
        chroot $rootfs apt-get install --force-yes -y lxcguest

        # Restore old resolv.conf
        rm -f ${cresolvonf}
        mv ${cresolvonf}.lxcbak ${cresolvonf}
    fi

    # If the container isn't running a native architecture, setup multiarch
    if [ -x "$(ls -1 ${rootfs}/usr/bin/qemu-*-static 2>/dev/null)" ]; then
        dpkg_version=$(chroot $rootfs dpkg-query -W -f='${Version}' dpkg)
        if chroot $rootfs dpkg --compare-versions $dpkg_version ge "1.16.2"; then
            chroot $rootfs dpkg --add-architecture ${hostarch}
        else
            mkdir -p ${rootfs}/etc/dpkg/dpkg.cfg.d
            echo "foreign-architecture ${hostarch}" > ${rootfs}/etc/dpkg/dpkg.cfg.d/lxc-multiarch
        fi

        # Save existing value of MIRROR and SECURITY_MIRROR
        DEFAULT_MIRROR=$MIRROR
        DEFAULT_SECURITY_MIRROR=$SECURITY_MIRROR

        # Write a new sources.list containing both native and multiarch entries
        > ${rootfs}/etc/apt/sources.list
        write_sourceslist $rootfs $arch "native"

        MIRROR=$DEFAULT_MIRROR
        SECURITY_MIRROR=$DEFAULT_SECURITY_MIRROR
        write_sourceslist $rootfs $hostarch "multiarch"

        # Finally update the lists and install upstart using the host architecture
        chroot $rootfs apt-get update
        chroot $rootfs apt-get install --force-yes -y --no-install-recommends upstart:${hostarch} mountall:${hostarch} iproute:${hostarch} isc-dhcp-client:${hostarch}
    fi

    # rmdir /dev/shm for containers that have /run/shm
    # I'm afraid of doing rm -rf $rootfs/dev/shm, in case it did
    # get bind mounted to the host's /run/shm.  So try to rmdir
    # it, and in case that fails move it out of the way.
    if [ -d $rootfs/run/shm ]; then
        [ -d "$rootfs/dev/shm" ] && rmdir $rootfs/dev/shm
        [ -e "$rootfs/dev/shm" ] && mv $rootfs/dev/shm $rootfs/dev/shm.bak
        ln -s /run/shm $rootfs/dev/shm
    fi
}

do_bindhome()
{
    rootfs=$1
    user=$2

    # copy /etc/passwd, /etc/shadow, and /etc/group entries into container
    pwd=`getent passwd $user` || { echo "Failed to copy password entry for $user"; false; }
    echo $pwd >> $rootfs/etc/passwd

    # make sure user's shell exists in the container
    shell=`echo $pwd | cut -d: -f 7`
    if [ ! -x $rootfs/$shell ]; then
        echo "shell $shell for user $user was not found in the container."
        pkg=`dpkg -S $(readlink -m $shell) | cut -d ':' -f1`
        echo "Installing $pkg"
        chroot $rootfs apt-get --force-yes -y install $pkg
    fi

    shad=`getent shadow $user`
    echo "$shad" >> $rootfs/etc/shadow

    # bind-mount the user's path into the container's /home
    h=`getent passwd $user | cut -d: -f 6`
    mkdir -p $rootfs/$h

    # use relative path in container
    h2=${h#/}
    while [ ${h2:0:1} = "/" ]; do
        h2=${h2#/}
    done
    echo "$h $h2 none bind 0 0" >> $path/fstab

    # Make sure the group exists in container
    grp=`echo $pwd | cut -d: -f 4`  # group number for $user
    grpe=`getent group $grp` || return 0  # if host doesn't define grp, ignore in container
    chroot $rootfs getent group "$grpe" || echo "$grpe" >> $rootfs/etc/group
}

usage()
{
    cat <<EOF
$1 -h|--help [-a|--arch] [-b|--bindhome <user>] [--trim] [-d|--debug]
   [-F | --flush-cache] [-r|--release <release>] [ -S | --auth-key <keyfile>]
release: the ubuntu release (e.g. precise): defaults to host release on ubuntu, otherwise uses latest LTS
trim: make a minimal (faster, but not upgrade-safe) container
bindhome: bind <user>'s home into the container
          The ubuntu user will not be created, and <user> will have
          sudo access.
arch: the container architecture (e.g. amd64): defaults to host arch
auth-key: SSH Public key file to inject into container
EOF
    return 0
}

options=$(getopt -o a:b:hp:r:xn:FS:d -l arch:,bindhome:,help,path:,release:,trim,name:,flush-cache,auth-key:,debug -- "$@")
if [ $? -ne 0 ]; then
    usage $(basename $0)
    exit 1
fi
eval set -- "$options"

release=precise # Default to the last Ubuntu LTS release for non-Ubuntu systems
if [ -f /etc/lsb-release ]; then
    . /etc/lsb-release
    if [ "$DISTRIB_ID" = "Ubuntu" ]; then
        release=$DISTRIB_CODENAME
    fi
fi

bindhome=
arch=$(uname -m)

# Code taken from debootstrap
if [ -x /usr/bin/dpkg ] && /usr/bin/dpkg --print-architecture >/dev/null 2>&1; then
    arch=`/usr/bin/dpkg --print-architecture`
elif type udpkg >/dev/null 2>&1 && udpkg --print-architecture >/dev/null 2>&1; then
    arch=`/usr/bin/udpkg --print-architecture`
else
    arch=$(uname -m)
    if [ "$arch" = "i686" ]; then
        arch="i386"
    elif [ "$arch" = "x86_64" ]; then
        arch="amd64"
    elif [ "$arch" = "armv7l" ]; then
        arch="armel"
    fi
fi

debug=0
trim_container=0
hostarch=$arch
flushcache=0
while true
do
    case "$1" in
    -h|--help)      usage $0 && exit 0;;
    -p|--path)      path=$2; shift 2;;
    -n|--name)      name=$2; shift 2;;
    -F|--flush-cache) flushcache=1; shift 1;;
    -r|--release)   release=$2; shift 2;;
    -b|--bindhome)  bindhome=$2; shift 2;;
    -a|--arch)      arch=$2; shift 2;;
    -x|--trim)      trim_container=1; shift 1;;
    -S|--auth-key)  auth_key=$2; shift 2;;
    -d|--debug)     debug=1; shift 1;;
    --)             shift 1; break ;;
        *)              break ;;
    esac
done

if [ $debug -eq 1 ]; then
    set -x
fi

if [ -n "$bindhome" ]; then
    pwd=`getent passwd $bindhome`
    if [ $? -ne 0 ]; then
        echo "Error: no password entry found for $bindhome"
        exit 1
    fi
fi


if [ "$arch" == "i686" ]; then
    arch=i386
fi

if [ $hostarch = "i386" -a $arch = "amd64" ]; then
    echo "can't create amd64 container on i386"
    exit 1
fi

type debootstrap
if [ $? -ne 0 ]; then
    echo "'debootstrap' command is missing"
    exit 1
fi

if [ -z "$path" ]; then
    echo "'path' parameter is required"
    exit 1
fi

if [ "$(id -u)" != "0" ]; then
    echo "This script should be run as 'root'"
    exit 1
fi

rootfs=$path/rootfs

install_ubuntu $rootfs $release $flushcache
if [ $? -ne 0 ]; then
    echo "failed to install ubuntu $release"
    exit 1
fi

configure_ubuntu $rootfs $name $release
if [ $? -ne 0 ]; then
    echo "failed to configure ubuntu $release for a container"
    exit 1
fi

copy_configuration $path $rootfs $name $arch $release
if [ $? -ne 0 ]; then
    echo "failed write configuration file"
    exit 1
fi

post_process $rootfs $release $trim_container

if [ -n "$bindhome" ]; then
    do_bindhome $rootfs $bindhome
    finalize_user $bindhome
else
    finalize_user ubuntu
fi

echo ""
echo "##"
echo "# The default user is 'ubuntu' with password 'ubuntu'!"
echo "# Use the 'sudo' command to run tasks as root in the container."
echo "##"
echo ""