#!/bin/bash

# script to run once a day to:
# a. say which backup drive is connected
# b. generate an rsnapshot du report
# c. collect accumulated hourly logs
# d. mail it all to the rsnapshot admins
# must be run as root

# assumes /etc/crontab something like this:
#0 */8 * * * root /usr/bin/rsnapshot hourly 2>&1 | \
# tee /tmp/rsnapreport-hourly.log | /usr/bin/rsnapreport.pl \
# >>/root/cron/rsnapshot-hourly.log && /bin/echo >> \
# /root/cron/rsnapshot-hourly.log
#50 23 * * * root /usr/bin/rsnapshot daily > /tmp/rsnapreport-daily.log
#40 23 * * 6 root /usr/bin/rsnapshot weekly > /tmp/rsnapshot-weekly.log
#30 23 1 * * root /usr/bin/rsnapshot monthly > /tmp/rsnapshot-monthly.log
#1 6 * * * root /usr/local/sbin/rsnapshot-du

AdminEmail=rsnapshot
RsnapDuCmd="/usr/bin/rsnapshot du"
BackupDevice=/dev/sdd1
BackupDir=/misc/backup
FsLabel=""
ScriptBase=$(basename $0)
LogFile=/var/log/rsnapshot
HourlyLogs=/root/cron/rsnapshot-hourly.log

# are we running as root?
[ $(id -u) -eq 0 ] || \
  { echo "$0 must be run as root" >&2; exit 1; };

# clean up if we abort.
trap "rm -f $RsnapDuFile; exit 3" TERM INT

# make a tempfile to hold the du output so we can mail it later.
RsnapDuFile=$(mktemp -t ${ScriptBase}.XXXXX) || \
  { echo "failed to create tempfile." >&2; exit 1; };

# check that one of the backup drives is connected.
FsLabel=$(/sbin/e2label $BackupDevice) ||
  { echo "failed to get label of $BackupDevice - external drive not connected?" >&2; \
    exit 1; };

echo -n "rsnapshot backup disk usage for " > $RsnapDuFile
date +%D >> $RsnapDuFile
echo >> $RsnapDuFile
echo "Attached backup disk: $FsLabel" >> $RsnapDuFile
echo >> $RsnapDuFile

# Check amount of free space on the backup drive.
DfLine=$(df -h $BackupDir | tail -1)
# convert DfLine into a bash array...
DfLine=(${DfLine// / })

# "disk: ${DfLine[0]}"
# "size: ${DfLine[1]}"
# "used: ${DfLine[2]}"
# "avail: ${DfLine[3]}"
# "cap: ${DfLine[4]}"
# "mount: ${DfLine[5]}"

echo -n ${DfLine[3]} >> $RsnapDuFile
echo " free space remaining on $FsLabel" >> $RsnapDuFile

echo >> $RsnapDuFile

# generate the rsnapshot du report
echo "$RsnapDuCmd says:" >> $RsnapDuFile
echo >> $RsnapDuFile
$RsnapDuCmd >> $RsnapDuFile ||
  { echo "problem running $RsnapDuCmd" >&2; exit 1; };

# Dump collected hourly logs into the report.
echo >> $RsnapDuFile
echo "Hourly rsnapshot logs from the last 24 hours:" >>  $RsnapDuFile
echo >> $RsnapDuFile
cat $HourlyLogs >> $RsnapDuFile
# Reset until next run.
rm -f $HourlyLogs

# ok now we are ready to mail and delete the tempfile.
cat $RsnapDuFile | mail -s "rsnapshot disk usage report" $AdminEmail
rm -f $RsnapDuFile

# log which disk is attached, might be useful for later stats
LogDate=$(date "+[%d/%b/%Y:%H:%M:%S]")
echo "$LogDate backup disk $FsLabel is attached" >> $LogFile

exit 0