Remote backup of an OpenVZ host using duplicity and LVM snapshots

The following script was developed and tested under Debian Lenny.

#!/bin/bash
###################################################################
#
# This shell script creates remote incremental backups
# from all of your OpenVZ virtual environments using
# duplicity and LVM snapshots. This uses far less space than
# the vzdump utility but is not as configurable.
# 
# The script is meant to be run from cron.daily. It sends
# its output to stdout and syslog. Modify log_real() to override.
#
# GPLv3 2009 by Erno Rigo <erno_AT_rigo_DOT_info>
#
# also see: http://wwww.openvz.org/
#           http://duplicity.nongnu.org/
#
###################################################################
# script configuration section
 
# backup destination host
DEST_HOST="my.backup.host.example.com"
# username on destination (you should setup a key-based passwordless 
# ssh account for this purpose - see man ssh-keygen)
DEST_USER="root" 
# absolute path on backup destination - should start but not end with /
DEST_PATH="/BACKUPS"
 
# prefix to use everywhere - this should be an unique backup ID
PREFIX="vzbackup"
 
# OpenVZ configuration directory location - usually /etc/vz/conf 
VZCONF=/etc/vz/conf
 
# extended regular expression to filter VE config file list with
# eg.: set this to '(100|230).conf$' in order to just backup VE ID 100 and 230
# all VE-s will be backed up if you leave this empty
EXCLUDE_VE_REGEX=""
 
# LVM snapshot volume size - you should have at least 10-20% of
# your LV size available within the same VG to have snapshotting work reliably
SNAPSIZE=600M
 
# additional options for duplicity
# should at least specify --full-if-older-than
# you should setup encryption here if you need it
DUPLICITY_OPTS="--no-encryption --volsize 100 --full-if-older-than 1W"
 
# number of full backups to keep
# minimum backup window size = full-if-older-than * KEEP 
KEEP=2
 
###################################################################
# do not touch bellow this line unless
# you know what you're doing
 
# destination URL for duplicity
# note: since duplicity cannot autmatically create
# its destination directory, only ssh is supported for now
DEST="ssh://$DEST_USER@$DEST_HOST/$DEST_PATH"
 
# this is the main log function
# it sends output to stdout and the logger
log_real() {
    if [ $# -eq 0 ]; then
        parm=`cat`
    else
        parm="$@"
    fi
    echo -e "$parm" | while read line; do
        echo "+ $line" | logger -s -t "$0"
    done
}
 
# normal log message
log() {
    log_real "$@"
}
 
# fatal log message
fatal() {
    log_real "FATAL: $@"
    echo "-1" > $EXITCODEFILE
    exit -1
}
 
# initialization
do_init() {
    log $0 initializing... 
    trap "do_cleanup 2>&1 | log" exit
    TMPDIR=`mktemp -t -d $PREFIX.XXXXXXXXXX || fatal unable to mktemp`
    EXITCODEFILE=`mktemp -p "$TMPDIR" || fatal unable to mktemp`
    echo 0 > $EXITCODEFILE
}
 
# cleanup function (called from the "exit" bash trap)
do_cleanup() {
    echo "cleaning up $TMPDIR (errors bellow this line can be ignored safely)"
    umount -f "$TMPDIR/snapshot"
    [ -f "$TMPDIR/snapdev" ] && snapdev=`cat "$TMPDIR/snapdev"` && lvs "$snapdev" && do_cmd lvremove -f "$snapdev"
    rm -rf --one-file-system "$TMPDIR"
    echo "cleanup done"
}
 
# run generic shell command. logs and exits if command fails
do_cmd_real() {
    type="$1"
    shift 1
    #id=$RANDOM
    #echo "executing command id#$id: $@" >&2
    out=`mktemp -p "$TMPDIR" || fatal unable to mktemp` >&2
    case "$type" in
        echo)
            "$@" 2>&1 | tee "$out" >&2
            ;;
        noecho)
            "$@" 2>&1 > "$out"
            ;;
    esac
    ecode=$?
    [ $ecode -ne 0 ] && fatal "exit code $ecode for command: $@"
    cat "$out"
    rm -f "$out"
}
 
# normal command execution
do_cmd() {
    do_cmd_real noecho "$@"
}
 
# command execution with output logging
do_cmd_log() {
    do_cmd_real echo "$@"
}
 
# dump a specific VE (identified by VEID and config file path)
do_dumpve() {
    veid="$1"
    conf="$2"
 
    # discover environment
    private=`( VEID=$veid ; . "$conf" ; readlink -f $VE_PRIVATE )`
    dev=`do_cmd df -P -T "$private" | tail -n+2 | awk '{print $1}'`
    fstype=`do_cmd df -P -T "$private" | tail -n+2 | awk '{print $2}'`
    mountpoint=`do_cmd df -P -T "$private" | tail -n+2 | awk '{print $7}'`
    mountpoint=`readlink -f $mountpoint`
    relprivate=`echo "$private" | cut -b$(echo "$mountpoint" | wc -c)- `
    absprivate="$TMPDIR/snapshot/$relprivate"
    lv=`do_cmd lvs -o lv_name --rows --separator ":" $dev | cut -f2 -d':'`
    vg=`do_cmd lvs -o vg_name --rows --separator ":" $dev | cut -f2 -d':'`
    lvdev="/dev/$vg/$lv"
 
    # amuse user
    # echo "VE $veid config:$conf private:$private device:$dev lvdev:$lvdev mountpoint:$mountpoint relprivate:$relprivate"
    echo "VE $veid lvdev:$lvdev mountpoint:$mountpoint relprivate:$relprivate fstype:$fstype"
 
    # prepare and mount snapshot
    do_cmd lvcreate --size $SNAPSIZE --snapshot --name "$PREFIX-snapshot" $lvdev
    echo "/dev/$vg/$PREFIX-snapshot" > "$TMPDIR/snapdev"
    do_cmd mkdir -p "$TMPDIR/snapshot"
    do_cmd mount -v -t "$fstype" "/dev/$vg/$PREFIX-snapshot" "$TMPDIR/snapshot"
 
    # backup VE using duplicity
    pushd "$absprivate" >/dev/null
    mkdir -p "$TMPDIR/dirs/$PREFIX-$veid"
    do_cmd scp -r "$TMPDIR/dirs/$PREFIX-$veid" "$DEST_USER@$DEST_HOST:/$DEST_PATH/"
    do_cmd duplicity cleanup $DUPLICITY_OPTS "$DEST/$PREFIX-$veid/"
    do_cmd duplicity $DUPLICITY_OPTS ./ "$DEST/$PREFIX-$veid/"
    do_cmd duplicity remove-all-but-n-full $KEEP $DUPLICITY_OPTS "$DEST/$PREFIX-$veid/"
    popd >/dev/null
 
    # unmount and remove snapshot
    do_cmd umount -v "$TMPDIR/snapshot"
    do_cmd lvremove -f "/dev/$vg/$PREFIX-snapshot"
}
 
# find VEs to backup - call do_dumpve() for each
do_work() {
    echo "running"
 
    do_cmd find "$VZCONF" -type f | do_cmd egrep "^$VZCONF/?[0-9]{2,}.conf\$" | do_cmd egrep "$EXCLUDE_VE_REGEX" | sort -n | uniq | while read conf; do
        veid=`echo "$conf" | rev | cut -f2 -d'.' | egrep -o "^[0-9]+" | rev`
        echo "backing up VE $veid"
        do_dumpve "$veid" "$conf"
        echo "done backing up VE $veid"
    done
 
}
 
# script entry point - send everything to the log() function
{ do_init || fatal "unable to init" ;} && { do_work 2>&1 | log ;}
 
# exit with the defined exit code (defaults to 0)
ecode=`cat "$EXITCODEFILE"`
log "done, exiting with code:$ecode"
exit $ecode
 
###################################################################
# end of file
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