check_btrfs_scrub

#!/bin/bash

BTRFS="/bin/btrfs"
AGE_WARNING=""
while [ $# -gt 0 ]; do
  [ "$1" == "--volume" ] && shift && FS="$1" && shift && continue
  [ "$1" == "--age-warning" ] && shift && AGE_WARNING="$1" && shift && continue
  echo "CRITICAL: Unknown option: $1"
  exit 2
done

[ -z "$FS" -o ! -e "$FS" ] && echo "No such directory: $FS" && exit 2

RAW="$("$BTRFS" scrub status -R "$FS")"
if [ $? -ne 0 ]; then
  echo "CRITICAL: Cannot get scrub status of $FS"
  exit 2
fi

if ! egrep -q "scrub (started|resumed)" <<<"$RAW"; then
  echo "CRITICAL: Filesystem has never been scrubbed."
  exit 2
fi

ERRORS="$(echo "$RAW" | egrep '_errors' | egrep -v ' 0$')"
if [ -n "$ERRORS" ]; then
  echo "CRITICAL: Scrub errors found:" $ERRORS
  exit 2
fi

if egrep -q "scrub (started|resumed) .* finished .*" <<<"$RAW"; then
  # scrub started at Sat Oct 14 00:10:00 2017 and finished after 08:57:46
  DURATION="$(echo "$RAW" | egrep -o 'finished after ..:..:..$' | sed 's/finished after //g')";
  START="$(echo "$RAW" | egrep -o "scrub [^ ]* at ... ... .. ..:..:.. ...." | sed 's/scrub [^ ]* at //g')"
  END="$(date -d "$START + $(echo "$DURATION" | sed 's/\(..\):\(..\):\(..\)/\1 hours + \2 minutes + \3 seconds/')")"
  AGE=$(( $(date +%s) - $(date -d "$END" +%s)  ))
  if [ -z "$START" -o -z "$END" -o -z "$AGE" ]; then
    echo "WARNING: CANNOT DETERMINE AGE OF SCRUB: Last scrub finished without finding errors:" $(egrep "scrub (started|resumed) .* finished .*" <<<"$RAW")
  fi
  if [ -n "$AGE_WARNING" ] && [ "$AGE_WARNING" -lt "$AGE" ]; then
    echo "WARNING: SCRUB TOO OLD: Scrub finished $AGE seconds ago without finding errors:" $(egrep "scrub (started|resumed) .* finished .*" <<<"$RAW")
    exit 1
  fi
  echo "OK: Scrub finished $AGE seconds ago without finding errors:" $(egrep "scrub (started|resumed) .* finished .*" <<<"$RAW")
  exit 0
fi

echo WARNING: $(egrep "scrub (started|resumed)" <<<"$RAW")
exit 1