lxc 技術實際創造出 ubuntu 容器的腳本

我了解到三件事

1. 這是 canonical 官方人員所寫，代表容器技術團隊與OS技術團隊有深度合作
2. 看起來就是 bash 腳本而已
3. 對於容器技術要再深入了解，就從這邊開始往下，看實際腳本最清楚

type: cat /usr/share/lxc/templates/lxc-ubuntu

and then you will see...

#!/bin/bash

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

# Copyright © 2011 Serge Hallyn <[email protected]>
# Copyright © 2010 Wilhelm Meier
# Author: Wilhelm Meier <[email protected]>
#
#  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., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA

# Detect use under userns (unsupported)
for arg in "$@"; do
    [ "$arg" = "--" ] && break
    if [ "$arg" = "--mapped-uid" -o "$arg" = "--mapped-gid" ]; then
        echo "This template can't be used for unprivileged containers." 1>&2
        echo "You may want to try the \"download\" template instead." 1>&2
        exit 1
    fi
done

# Make sure the usual locations are in PATH
export PATH=$PATH:/usr/sbin:/usr/bin:/sbin:/bin

set -e

LOCALSTATEDIR="/var"
LXC_TEMPLATE_CONFIG="/usr/share/lxc/config"
# Allows the lxc-cache directory to be set by environment variable
LXC_CACHE_PATH=${LXC_CACHE_PATH:-"$LOCALSTATEDIR/cache/lxc"}

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

# Check if given path is in a btrfs partition
is_btrfs()
{
    [ -e $1 -a $(stat -f -c '%T' $1) = "btrfs" ]
}

# Check if given path is the root of a btrfs subvolume
is_btrfs_subvolume()
{
    [ -d $1 -a $(stat -f -c '%T' $1) = "btrfs" -a $(stat -c '%i' $1) -eq 256 ]
}

try_mksubvolume()
{
    path=$1
    [ -d $path ] && return 0
    mkdir -p $(dirname $path)
    if which btrfs >/dev/null 2>&1 && is_btrfs $(dirname $path); then
        btrfs subvolume create $path
    else
        mkdir -p $path
    fi
}

try_rmsubvolume()
{
    path=$1
    [ -d $path ] || return 0
    if which btrfs >/dev/null 2>&1 && is_btrfs_subvolume $path; then
        btrfs subvolume delete $path
    else
        rm -rf $path
    fi
}

configure_ubuntu()
{
    rootfs=$1
    hostname=$2
    release=$3
    user=$4
    password=$5

    # configure the network using the dhcp
    if chroot $rootfs which netplan >/dev/null 2>&1; then
        cat <<EOF > $rootfs/etc/netplan/10-lxc.yaml
network:
  ethernets:
    eth0: {dhcp4: true}
  version: 2
EOF
    else
        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
    fi

    # 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 $user
        echo "$user:$password" | chroot $rootfs chpasswd
    fi

    # make sure we have the current locale defined in the container
    if [ -z "$LANG" ] || echo $LANG | grep -E -q "^C(\..+)*$"; then
        chroot $rootfs locale-gen en_US.UTF-8 || true
        chroot $rootfs update-locale LANG=en_US.UTF-8 || true
    else
        chroot $rootfs locale-gen $LANG || true
        chroot $rootfs update-locale LANG=$LANG || true
    fi

    # generate new SSH keys
    if [ -x $rootfs/var/lib/dpkg/info/openssh-server.postinst ]; then
        cat > $rootfs/usr/sbin/policy-rc.d << EOF
#!/bin/sh
exit 101
EOF
        chmod +x $rootfs/usr/sbin/policy-rc.d

        if [ -f "$rootfs/etc/init/ssh.conf" ]; then
            mv "$rootfs/etc/init/ssh.conf" "$rootfs/etc/init/ssh.conf.disabled"
        fi

        rm -f $rootfs/etc/ssh/ssh_host_*key*

        DPKG_MAINTSCRIPT_PACKAGE=openssh DPKG_MAINTSCRIPT_NAME=postinst chroot $rootfs /var/lib/dpkg/info/openssh-server.postinst configure

        sed -i "s/root@$(hostname)/root@$hostname/g" $rootfs/etc/ssh/ssh_host_*.pub

        if [ -f "$rootfs/etc/init/ssh.conf.disabled" ]; then
            mv "$rootfs/etc/init/ssh.conf.disabled" "$rootfs/etc/init/ssh.conf"
        fi

        rm -f $rootfs/usr/sbin/policy-rc.d
    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
}

# A function to try and autodetect squid-deb-proxy servers on the local network
# if either the squid-deb-proxy-client package is installed on the host or
# a parent container set the 50squid-deb-proxy-client file.
squid_deb_proxy_autodetect()
{
    local apt_discover=/usr/share/squid-deb-proxy-client/apt-avahi-discover
    local proxy_file=/etc/apt/apt.conf.d/50squid-deb-proxy-client
    squid_proxy_line=  # That's a global :/

    # Maybe the host is aware of a squid-deb-proxy?
    if [ -f $apt_discover ]; then
        echo -n "Discovering squid-deb-proxy..."
        squid_proxy_line=$($apt_discover)
        if [ -n "$squid_proxy_line" ]; then
            echo "found squid-deb-proxy: $squid_proxy_line"
        else
            echo "no squid-deb-proxy found"
        fi
    fi

    # Are we in a nested container, and the parent already knows of a proxy?
    if [ -f $proxy_file ]; then
        # Extract the squid URL from the file (whatever is between "")
        squid_proxy_line=`cat $proxy_file | sed "s/.*\"\(.*\)\".*/\1/"`
    fi
}

#
# Choose proxies for container
# http_proxy will be used by debootstrap on the host.
# APT_PROXY will be used to set /etc/apt/apt.conf.d/70proxy in the container.
#
choose_container_proxy()
{
    local rootfs=$1
    local arch=$2

    if [ -z "$HTTP_PROXY" ]; then
        HTTP_PROXY="none"
    fi
    case "$HTTP_PROXY" in
    none)
        squid_deb_proxy_autodetect
        if [ -n "$squid_proxy_line" ]; then
            APT_PROXY=$squid_proxy_line
            export http_proxy=$squid_proxy_line
        else
            APT_PROXY=
        fi
        ;;
    apt)
        RES=`apt-config shell APT_PROXY Acquire::http::Proxy`
        eval $RES
        [ -z "$APT_PROXY" ] || export http_proxy=$APT_PROXY
        ;;
    *)
        APT_PROXY=$HTTP_PROXY
        export http_proxy=$HTTP_PROXY
        ;;
    esac
}

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

    if [ -n "$APT_PROXY" ]; then
        mkdir -p $1/etc/apt/apt.conf.d
        cat > $1/etc/apt/apt.conf.d/70proxy << EOF
Acquire::http::Proxy "$APT_PROXY" ;
EOF
    fi

    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
}

install_packages()
{
    local rootfs="$1"
    shift
    local packages="$*"
    if [ -z $update ]
    then
        chroot $rootfs apt-get update
        update=true
    fi
    if [ -n "${packages}" ]
    then
        chroot $rootfs apt-get install --force-yes -y --no-install-recommends ${packages}
    fi
}

cleanup()
{
    try_rmsubvolume $cache/partial-$arch
    try_rmsubvolume $cache/rootfs-$arch
}

suggest_flush()
{
    echo "Container upgrade failed.  The container cache may be out of date,"
    echo "in which case flushing the cache (see -F in the help output) may help."
}

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

    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

    packages_template=${packages_template:-"apt-transport-https,ssh,vim"}
    debootstrap_parameters=

    # Try to guess a list of langpacks to install
    langpacks="language-pack-en"

    if which dpkg >/dev/null 2>&1; then
        langpacks=`(echo $langpacks &&
                    dpkg -l | grep -E "^ii  language-pack-[a-z]* " |
                        cut -d ' ' -f3) | sort -u`
    fi
    packages_template="${packages_template},$(echo $langpacks | sed 's/ /,/g')"

    if [ -n "$variant" ]; then
        debootstrap_parameters="$debootstrap_parameters --variant=$variant"
    fi
    if [ "$variant" = 'minbase' ]; then
        packages_template="${packages_template},sudo"
        # Newer releases use netplan, EOL releases not supported
        case $release in
          trusty|xenial|zesty)
                packages_template="${packages_template},ifupdown,isc-dhcp-client"
                ;;
        esac
    fi

    echo "Installing packages in template: ${packages_template}"

    trap cleanup EXIT SIGHUP SIGINT SIGTERM
    # check the mini ubuntu was not already downloaded
    try_mksubvolume "$cache/partial-$arch"
    if [ $? -ne 0 ]; then
        echo "Failed to create '$cache/partial-$arch' directory"
        return 1
    fi

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

    (
        cat << EOF
        mount -t proc proc "${1}/partial-${arch}/proc"
        chroot "${1}/partial-${arch}" apt-get dist-upgrade -y
EOF
    ) | lxc-unshare -s MOUNT -- sh -eu || (suggest_flush; false)

    rm -f "$1/partial-${arch}"/usr/sbin/policy-rc.d

    chroot "$1/partial-${arch}" apt-get clean

    mv "$1/partial-$arch" "$1/rootfs-$arch"
    trap EXIT
    trap SIGINT
    trap SIGTERM
    trap SIGHUP
    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 ..."
    try_mksubvolume $rootfs
    if which btrfs >/dev/null 2>&1 && is_btrfs_subvolume $cache/rootfs-$arch && is_btrfs_subvolume $rootfs; then
      realrootfs=$(dirname $config)/rootfs
      [ "$rootfs" = "$realrootfs" ] || umount $rootfs || return 1
      btrfs subvolume delete $realrootfs || return 1
      btrfs subvolume snapshot $cache/rootfs-$arch $realrootfs || return 1
      [ "$rootfs" = "$realrootfs" ] || mount --bind $realrootfs $rootfs || return 1
    else
      rsync -SHaAX $cache/rootfs-$arch/ $rootfs/ || return 1
    fi
    return 0
}

install_ubuntu()
{
    rootfs=$1
    release=$2
    flushcache=$3
    cache="$4/$release"
    mkdir -p $LOCALSTATEDIR/lock/subsys/

    (
        flock -x 9
        if [ $? -ne 0 ]; then
            echo "Cache repository is busy."
            return 1
        fi

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

    ) 9>$LOCALSTATEDIR/lock/subsys/lxc-ubuntu$release

    return $?
}

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

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

    # if there is exactly one veth network entry, make sure it has an
    # associated hwaddr.
    nics=`grep -e '^lxc\.net\.0\.type[ \t]*=[ \t]*veth' $path/config | wc -l`
    if [ $nics -eq 1 ]; then
        grep -q "^lxc.net.0.hwaddr" $path/config || sed -i -e "/^lxc\.net\.0\.type[ \t]*=[ \t]*veth/a lxc.net.0.hwaddr = 00:16:3e:$(openssl rand -hex 3| sed 's/\(..\)/\1:/g; s/.$//')" $path/config
    fi

    # Generate the configuration file
    ## Relocate all the network config entries
    sed -i -e "/lxc.net.0/{w ${path}/config-network" -e "d}" $path/config

    ## Relocate any other config entries
    sed -i -e "/lxc./{w ${path}/config-auto" -e "d}" $path/config

    ## Add all the includes
    echo "" >> $path/config
    echo "# Common configuration" >> $path/config
    if [ -e "${LXC_TEMPLATE_CONFIG}/ubuntu.common.conf" ]; then
        echo "lxc.include = ${LXC_TEMPLATE_CONFIG}/ubuntu.common.conf" >> $path/config
    fi
    if [ -e "${LXC_TEMPLATE_CONFIG}/ubuntu.${release}.conf" ]; then
        echo "lxc.include = ${LXC_TEMPLATE_CONFIG}/ubuntu.${release}.conf" >> $path/config
    fi

    ## Add the container-specific config
    echo "" >> $path/config
    echo "# Container specific configuration" >> $path/config
    [ -e "$path/config-auto" ] && cat $path/config-auto >> $path/config && rm $path/config-auto
    grep -q "^lxc.rootfs.path" $path/config 2>/dev/null || echo "lxc.rootfs.path = $rootfs" >> $path/config
    cat <<EOF >> $path/config
lxc.uts.name = $name
lxc.arch = $arch
EOF

    ## Re-add the previously removed network config
    echo "" >> $path/config
    echo "# Network configuration" >> $path/config
    cat $path/config-network >> $path/config
    rm $path/config-network

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

    return 0
}

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

    # Disable service startup
    cat > $rootfs/usr/sbin/policy-rc.d << EOF
#!/bin/sh
exit 101
EOF
    chmod +x $rootfs/usr/sbin/policy-rc.d

    # 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
        HOST_PACKAGES="upstart:${hostarch} mountall:${hostarch} isc-dhcp-client:${hostarch}"
        chroot $rootfs apt-get update
        if chroot $rootfs dpkg -l iproute2 | grep -q ^ii; then
            HOST_PACKAGES="$HOST_PACKAGES iproute2:${hostarch}"
        else
            HOST_PACKAGES="$HOST_PACKAGES iproute:${hostarch}"
        fi
        install_packages $rootfs $HOST_PACKAGES
    fi

    # Install Packages in container
    if [ -n "$packages" ]
    then
        local packages="`echo $packages | sed 's/,/ /g'`"
        echo "Installing packages: ${packages}"
        install_packages $rootfs $packages
    fi

    # Set initial timezone as on host
    if [ -f /etc/timezone ]; then
        cat /etc/timezone > $rootfs/etc/timezone
        chroot $rootfs dpkg-reconfigure -f noninteractive tzdata
    elif [ -f /etc/sysconfig/clock ]; then
        . /etc/sysconfig/clock
        echo $ZONE > $rootfs/etc/timezone
        chroot $rootfs dpkg-reconfigure -f noninteractive tzdata
    else
        echo "Timezone in container is not configured. Adjust it manually."
    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.
    # NOTE: This can only be removed once 12.04 goes out of support
    if [ ! -L $rootfs/dev/shm ] && [ -e $rootfs/dev/shm ]; then
        rmdir $rootfs/dev/shm 2>/dev/null || mv $rootfs/dev/shm $rootfs/dev/shm.bak
        ln -s /run/shm $rootfs/dev/shm
    fi

    # Re-enable service startup
    rm $rootfs/usr/sbin/policy-rc.d
}

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"
        install_packages $rootfs $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 "lxc.mount.entry = $h $h2 none bind 0 0" >> $path/config

    # 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>] [-d|--debug]
   [-F | --flush-cache] [-r|--release <release>] [-v|--variant] [ -S | --auth-key <keyfile>]
   [--rootfs <rootfs>] [--packages <packages>] [-u|--user <user>] [--password <password>]
   [--mirror <url>] [--security-mirror <url>]
release: the ubuntu release (e.g. xenial): defaults to host release on ubuntu, otherwise uses latest LTS
variant: debootstrap variant to use (see debootstrap(8))
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
packages: list of packages to add comma separated
mirror,security-mirror: mirror for download and /etc/apt/sources.list
EOF
    return 0
}

options=$(getopt -o a:b:hp:r:v:n:FS:du: -l arch:,bindhome:,help,path:,release:,variant:,name:,flush-cache,auth-key:,debug,rootfs:,packages:,user:,password:,mirror:,security-mirror: -- "$@")
if [ $? -ne 0 ]; then
    usage $(basename $0)
    exit 1
fi
eval set -- "$options"

release=xenial # 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=

# 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 which 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="armhf"
    elif [ "$arch" = "aarch64" ]; then
        arch="arm64"
    elif [ "$arch" = "ppc64le" ]; then
        arch="ppc64el"
    fi
fi

debug=0
hostarch=$arch
flushcache=0
packages=""
user="ubuntu"
password="ubuntu"

while true
do
    case "$1" in
    -h|--help)      usage $0 && exit 0;;
    --rootfs)       rootfs=$2; shift 2;;
    -p|--path)      path=$2; shift 2;;
    -n|--name)      name=$2; shift 2;;
    -u|--user)      user=$2; shift 2;;
    --password)     password=$2; shift 2;;
    -F|--flush-cache) flushcache=1; shift 1;;
    -r|--release)   release=$2; shift 2;;
    -v|--variant)   variant=$2; shift 2;;
    --packages)     packages=$2; shift 2;;
    -b|--bindhome)  bindhome=$2; shift 2;;
    -a|--arch)      arch=$2; shift 2;;
    -S|--auth-key)  auth_key=$2; shift 2;;
    -d|--debug)     debug=1; shift 1;;
    --mirror)       MIRROR=$2; shift 2;;
    --security-mirror) SECURITY_MIRROR=$2; shift 2;;
    --)             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 $arch container on $hostarch"
    exit 1
fi

if [ $hostarch = "armhf" -o $hostarch = "armel" -o $hostarch = "arm64" ] && \
   [ $arch != "armhf" -a $arch != "armel" -a $arch != "arm64" ]; then
    echo "can't create $arch container on $hostarch"
    exit 1
fi

if [ $arch = "arm64" ] && [ $hostarch != "arm64" ]; then
    echo "can't create $arch container on $hostarch"
    exit 1
fi

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

which debootstrap >/dev/null 2>&1 || { echo "'debootstrap' command is missing" >&2; false; }

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

# detect rootfs
config="$path/config"
# if $rootfs exists here, it was passed in with --rootfs
if [ -z "$rootfs" ]; then
    if grep -q '^lxc.rootfs.path' $config 2>/dev/null ; then
        rootfs=$(awk -F= '/^lxc.rootfs.path =/{ print $2 }' $config)
    else
        rootfs=$path/rootfs
    fi
fi

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

configure_ubuntu $rootfs $name $release $user $password
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 $packages

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

echo ""
echo "##"
if [ -n "$bindhome" ]; then
    echo "# Log in as user $bindhome"
else
    echo "# The default user is '$user' with password '$password'!"
    echo "# Use the 'sudo' command to run tasks as root in the container."
fi
echo "##"
echo ""