btrfs scrub: script and systemd timers to run monthly

## btrfs-scrub
#! /bin/bash
#######################################################
# This is a helper script to be used in a systemd timer
# or cron job to scrub all mounted btrfs filessytems
#
# $Author: gbrks
# $Revision 0.1
# $Date: 2015.05.15
#
# Update email address below

EMAIL_SUBJECT_PREFIX="$HOSTNAME BTRFS - "
EMAIL_ADDRESS="<email@address>"

#Mailgun API
MG_API="api:key-<apikey>"
MG_DOMAIN="<domain>"
MG_FROM="<email_from>"

LOG_FILE="/var/log/btrfs-scrub.log"

TMP_OUTPUT="/tmp/btrfs-scrub.out"
# redirect all stdout to log gile
exec >> $LOG_FILE
# timestamp the job
echo "[`date`] btrfs scrub job started."
echo "btrfs scrub job started on `date`" > $TMP_OUTPUT
echo "----------------------------------------" >> $TMP_OUTPUT

# for each btrfs type system mounted, scrub and record output
while read d m t x
do
  [[ $t != "btrfs" ]] && continue
  echo "scrubbing $m" >> $TMP_OUTPUT
  echo "[`date`] scrubbing $m"
  btrfs scrub start -Bd $m >> $TMP_OUTPUT
  echo "" >> $TMP_OUTPUT
done </proc/mounts

echo "----------------------------------------" >> $TMP_OUTPUT
echo "btrfs scrub job finished on `date`" >> $TMP_OUTPUT

curl -s --user "$MG_API" \
  https://api.mailgun.net/v3/$MG_DOMAIN/messages \
  -F from="$MG_FROM" \
  -F to="$EMAIL_ADDRESS" \
  -F subject="$EMAIL_SUBJECT_PREFIX Scrub Job Completed" \
  -F text="$(cat $TMP_OUTPUT)" \


echo "[`date`] Scrub job ended."
exit 0;

## btrfs-scrub.service
[Unit]
Description=btrfs scrub

[Service]
Type=simple
ExecStart=/usr/local/bin/btrfs-scrub

## btrfs-scrub.timer
[Unit]
Description=Runs btrfs scrub on all discs monthly

[Timer]
OnCalendar=monthly

[Install]
WantedBy=timers.target