raspi-backup-btrfs

#!/bin/bash

set -eu
set -o pipefail

# target directory
target='/media/backup/$(hostname -s)'

# list of files to exclude
exclude_files='var/swap var/log/wtmp'

##
# rsync=(no|alive|yes)
# no    - no rsync
# alive - run rsync if host is alive
# yes   - always run rsync
#
rsync=no

# rsync host
rsync_host='nas'

# rsync target
rsync_target="rsync://$rsync_host/backup/$(hostname -s)"

# how long to keep in days
keep=14

# compress command
compress='gzip'

# archive extension
ext='tar.gz'

# number of snapshots to keep
snapkeep=5

# snapshots directory
snapdir='/.btrfs/.snapshots'

# =========================================================================

timestamp=$(date +%Y.%m.%d)

test -r $HOME/.raspi-backup-btrfs && source $HOME/.raspi-backup-btrfs

PATH=/usr/local/bin:$PATH:/sbin

ts=$timestamp
out=$(mktemp)
excl=$(mktemp)
rc=$(mktemp)
restore=$target/$ts/restore

function epilogue()
{
  _rc=$?
  test $_rc -eq 0 && status=ok || status=failed

  echo "$(date) - backup $status"
  (
    cat $out
    test -f $target/${ts}/backup.out && cat $target/${ts}/backup.out
  ) | mail "$(hostname -s) backup $status"

  rm $excl $out $rc

  test -f $snapdir/$ts/boot/firmware/cmdline.txt && {
    umount $snapdir/$ts/boot/firmware
  }

  exit $_rc
}

trap epilogue EXIT

exec > $out 2>&1

until apt-get clean all; do sleep 30; done

test -d $target || {
  1>&2 echo "The directory '$target' does not exist!"
  exit 1
}

test -f $target/$ts/backup.ok && {
  echo "$(date) - backup already exists"
  exit 0
}

mkdir -p $target/$ts

exec > $target/$ts/backup.out 2>&1

echo "$(date) - backup start"

cat <<EOF > $restore
#!/bin/bash
set -eu
if [ \${#} -ne 1 ] || [ ! -d "\$1" ]; then
  echo "usage: \$0 <TARGET-DIR>"
  exit 1
fi
scriptdir=\$PWD
cat=\$(which pv) || cat=cat
set -x
set -o pipefail
function decompress()
{
  $compress -d
}
cd "\$1"
\$cat \$scriptdir/backup.$ext | decompress | tar -x --numeric-owner -f -
EOF

for file in $exclude_files ; do
  echo "./$file" >> $excl
done

test -d $snapdir/$ts || {
  btrfs subvolume snapshot -r / $snapdir/$ts
}
cd $snapdir/$ts

set -- $(mount | grep 'on /boot/firmware type')
mount $1 boot/firmware

(
  set +e
  tar --create -f - --exclude-from=$excl --one-file-system --warning=no-file-ignored --exclude-caches . boot/firmware
  echo $?>$rc
) | $compress > $target/$ts/backup.$ext.new
case $(cat $rc) in
0|1) true ;;
*) exit 2 ;;
esac

echo '
cd -
sync
' >> $restore

chmod +x $restore

cd $target/$ts

for file in backup.*.new ; do
  mv -f $file ${file%.new}
done

ls -lhrt
touch backup.ok

set -- $(LANG=C df $target/ -PT | grep -v '^Filesystem')
echo "$(date) - backup done ($6 used)"

echo "$(date) - reorg start"

##
# reorg
#
cd $target
for del in $(find * -type f -ctime +${keep}) ; do
  echo remove $del
  rm -f $del
done
for del in $(find * -type d -atime +${keep} -size 0) ; do
  echo remove $del
  rmdir $del
done

echo "$(date) - reorg done"


echo "$(date) - delete snapshots start"

cd $snapdir
n=$(ls | wc -l)
for s in $(ls | head -n$((n - snapkeep))); do
  btrfs subvolume delete $s
done

echo "$(date) - delete snapshots done"

##
# rsync
#
if [ "$rsync" == yes ] || (test "$rsync" == alive && ping $rsync_host -c 4 -q 2>/dev/null) ; then
  echo "$(date) - rsync start"
  cd $target
  rsync -rav $ts $rsync_target/
  echo "$(date) - rsync done"
fi

exit 0