backup-volume

#!/bin/bash

CONFIG_FILE="/etc/backup.conf"

print_error() {
  echo "error: $1" 1>&2; 
}

source $CONFIG_FILE 2>/dev/null || { print_error "could not read config file $CONFIG_FILE"; exit 127; }

volume_node() {
  echo "/dev/mapper/$1"
}

check_requirements() {
  local ret node

  ret=0

  [[ $EUID -eq 0 ]] || { print_error "this script must be run as root"; ret=1; }
  which lvcreate > /dev/null || { print_error "lvm tools not in PATH"; ret=2; }
  which duplicity > /dev/null || { print_error "duplicity not in PATH"; ret=2; }
  
  if [ -z "$1" ]; then
    print_error "must specify a volume to back up"
    ret=3;
  else
    node=$(volume_node $1)
    lvdisplay $node 2>&1 > /dev/null || { print_error "$node is not an LVM volume"; ret=3; }
  fi

  return $ret
}

create_snapshot() {
  lvcreate --verbose --size $2 -s $(volume_node $1) 2>&1 | grep -o -E \".*\" | tr -d \" | paste -s | awk '{print "/dev/"$1"/"$5}'
}

mount_snapshot() {
  local mountpoint

  mountpoint="/mnt/backup/$2"
  mkdir -p $mountpoint
  mount -r $1 $mountpoint

  echo $mountpoint
}

duplicity_do() {
  local cache
  cache="/var/cache/duplicity"

  for e in $BACKUP_EXCLUDES; do echo "./$e"; done \
    | AWS_ACCESS_KEY_ID=$BACKUP_AWS_KEY AWS_SECRET_ACCESS_KEY=$BACKUP_AWS_SECRET PASSPHRASE= duplicity \
                  --exclude-device-files --exclude-other-filesystems --exclude-if-present "./$cache" --exclude-filelist-stdin \
                  --archive-dir $cache --encrypt-secret-keyring $BACKUP_KEYRING --encrypt-sign-key $BACKUP_KEY \
                  --extra-clean --full-if-older-than $BACKUP_INTERVAL_FULL --s3-european-buckets --s3-unencrypted-connection \
                  --s3-use-new-style --s3-use-rrs --s3-use-multiprocessing --asynchronous-upload --extra-clean "$@"
}

backup() {
  (cd $1; duplicity_do incremental . $2)
  duplicity_do remove-older-than ${BACKUP_RETENTION:-3M} --force $2
  duplicity_do cleanup --force $2
}

backup_to_s3() {
  backup $1 "s3://s3-eu-west-1.amazonaws.com/$BACKUP_BUCKET/$(basename $1)"
}

unmount_snapshot() {
  umount -f $1
  rm -rf $1
}

remove_snapshot() {
  lvremove -f $1 > /dev/null
}

VOLUME=$(basename $1 2>/dev/null)
SNAPSHOT_SIZE=${2:-1G}

check_requirements $VOLUME || exit $?

SNAPSHOT=$(create_snapshot $VOLUME $SNAPSHOT_SIZE)
SNAPSHOT_MOUNT=$(mount_snapshot $SNAPSHOT $VOLUME)

backup_to_s3 $SNAPSHOT_MOUNT

unmount_snapshot $SNAPSHOT_MOUNT
remove_snapshot $SNAPSHOT