btrfs

# backupninja handler for incremental backups using btrfs send-receive
# feedback: pavel.cernocky at gmail.com
#
#  btrfs handler is free software; you can redistribute it and/or modify it
#  under the terms of the GNU General Public License as published by the Free
#  Software Foundation; either version 2 of the License, or any later version.
#
#  btrfs handler 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., 59 Temple
#  Place - Suite 330, Boston, MA 02111-1307, USA


# function definitions

function eval_config {
  debug "eval_config"
  
  # system section
  setsection system
  
  # general section
  setsection general
  getconf tmp /tmp
  
  # source section
  setsection source
  getconf subvolume; src_subvolume=$subvolume
  getconf btrfs btrfs; src_btrfs=$btrfs
  getconf type; src_type=$type
  if [ "$src_type" == "remote" ]; then
    getconf testconnect yes; src_testconnect=$testconnect
    getconf ssh ssh; src_ssh=$ssh
    getconf host; src_host=$host
    getconf port 22; src_port=$port
    getconf user; src_user=$user
    getconf ssh_options; src_ssh_options=$ssh_options
  fi
  
  # dest section
  setsection dest
  getconf directory; dst_directory=$directory
  getconf btrfs btrfs; dst_btrfs=$btrfs
  getconf type; dst_type=$type
  if [ "$dst_type" == "remote" ]; then
    getconf testconnect yes; dst_testconnect=$testconnect
    getconf ssh ssh; dst_ssh=$ssh
    getconf host; dst_host=$host
    getconf port 22; dst_port=$port
    getconf user; dst_user=$user
    getconf ssh_options; dst_ssh_options=$ssh_options
  fi
  
  # config check

  if [ "$src_type" != "local" ] && [ "$src_type" != "remote" ]; then
    fatal "Source type should be 'local' or 'remote'"
  fi

  if [ "$dst_type" != "local" ] && [ "$dst_type" != "remote" ]; then
    fatal "Dest type should be 'local' or 'remote'"
  fi

  check_var "src_subvolume"
  check_var "dst_directory"

  ssh_cmd_base="ssh -T -o PasswordAuthentication=no"
  if [ "$src_type" == "remote" ]; then
    check_var "src_user"
    check_var "src_host"
    src_ssh_cmd="$ssh_cmd_base -p $src_port $src_ssh_options $src_user@$src_host"
    if [ "$src_testconnect" == "yes" ]; then
      test_connect "$src_ssh_cmd" "$src_host" "$src_port" "$src_user"
    fi
  fi
  if [ "$dst_type" == "remote" ]; then
    check_var "dst_user"
    check_var "dst_host"
    dst_ssh_cmd="$ssh_cmd_base -p $dst_port $dst_ssh_options $dst_user@$dst_host"
    if [ "$dst_testconnect" == "yes" ]; then
      test_connect "$dst_ssh_cmd" "$dst_host" "$dst_port" "$dst_user"
    fi
  fi

}

function check_var {
  [[ -n "${!1}" ]] || { fatal "$1 is not set" ; }
}

function test_connect {
  local ssh_cmd="$1"
  local host="$2"
  local port="$3"
  local user="$4"

  debug "$ssh_cmd 'echo -n 1'"
  result=`$ssh_cmd 'echo -n 1'`

  if [ "$result" != "1" ]; then
    fatal "Can't connect to $host:$port as $user ($ssh_cmd)."
  else
    debug "Connected to $host as $user successfully"
  fi
}

# the backup procedure

eval_config

start_time=$(date +%s)

src_last_snapshot_filename="$src_subvolume.last-snapshot-name"

src_parent=$(dirname $src_subvolume)
dir=$(basename $src_subvolume)
dst_parent=$dst_directory
act="$dir.$(date -d@$start_time +%F.%H-%M-%S)"

src_act="$src_parent/$act"
dst_act="$dst_parent/$act"

if [ -e "$src_last_snapshot_filename" ]; then
  prev=$($src_ssh_cmd cat "$src_last_snapshot_filename")
  src_prev="$src_parent/$prev"
  dst_prev="$dst_parent/$prev"
fi

debug "src_last_snapshot_filename=$src_last_snapshot_filename"
debug "src_act=$src_act"
debug "src_prev=$src_prev"
debug "dst_act=$dst_act"
debug "dst_prev=$dst_prev"

info "----- $(date -d@$start_time +"%F %T") ----- Starting backup: $src_subvolume > $dst_act"

# create snapshot
$src_ssh_cmd $src_btrfs subvolume snapshot -r "$src_subvolume" "$src_act"
$src_ssh_cmd sync

# backup
pv_err=$(mktemp)
if [ ! -e "$src_prev" ]; then
  info "Last snapshot filename does not exist ($src_last_snapshot_filename), doing initial backup"
  $src_ssh_cmd $src_btrfs send "$src_act" | pv --wait --timer --rate --bytes --force 2>"$pv_err" | $dst_ssh_cmd $dst_btrfs receive "$dst_parent"
else
  $src_ssh_cmd $src_btrfs send -p "$src_prev" "$src_act" | pv --wait --timer --rate --bytes --force 2>"$pv_err" | $dst_ssh_cmd $dst_btrfs receive "$dst_parent"
fi

if [ $? -ne 0 ]; then
  fatal "Backup failed"
fi

info $(cat "$pv_err")
rm "$pv_err"

if [ -z "$src_ssh_cmd" ]; then
  $src_ssh_cmd echo "$act" > "$src_last_snapshot_filename"
else
  $src_ssh_cmd "echo $act > $src_last_snapshot_filename"
fi

end_time=$(date +%s)
elapsed=$(( $end_time - $start_time ))
info "----- $(date -d@$end_time +"%F %T") ----- Finished successfuly, elapsed $(date --utc -d@$elapsed +%T)"