#!/usr/bin/python

# Small script which takes output of "df -h", checks to see if the
# disk % used is above a threshhold, and if so, mails someone to
# alert them to a possible problem coming when the disk fills up.
#
# Usage: df -h | disk_space_check
#
# Expected to be run regularly from a cron job.
#
# Note that we COULD have done this completely from the command line,
# but our list host didn't provide anything like /bin/mail (binmail)
# for sending email from the command line.  So this script exists
# really just for connecting to SMTP server in a structured way, and
# so we can make a better-looking alert email than just a single line.
#
# The command-line version would be something like:
#
# df -h | egrep simfs | perl -ne '($fs, $sz, $used, $avail, $usep) = split(); ($usenum = $usep) =~ s#\%##; if ($usenum > 80) { print $usenum, qq^\n^;}; '
#
# Anthony R. Thompson, June 2010
# Contact: put @ between art and sigilservices.com
#
# Copyright (C) 1998-2010 by the Free Software Foundation, Inc.
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License
# as published by the Free Software Foundation; either version 2
# of the License, or (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
# 02110-1301, USA. http://www.fsf.org/licensing/licenses/gpl.html
#

import os, pwd, sys, re, smtplib, socket

recip = 'First Last <youremail@foo.com>'  # INSTALL (comma-sep OK for multi)

watchfs = '/'   # filesystem of interest to monitor
toofull = 90    # percentage which is "too full", i.e. notify admin

thisuser = pwd.getpwuid(os.getuid())[0]
thishost = socket.gethostname()
sender = thisuser + '@' + thishost

smtp_server = 'localhost'
subj = "Warning: %s disk space usage too high" % (thishost)

alldf = sys.stdin.readlines()   # to mail all later
fslines = alldf[1:]             # ignore header line

for line in fslines:
    (fstype, size, used, avail, usedp, mount) = re.split('\s+', line, 5)
    usedpnum = int(re.sub('%', '', usedp))
    mount = mount.rstrip("\n")

    if ( (mount == watchfs) and (usedpnum >= toofull) ):
        smtp = smtplib.SMTP(smtp_server)
        subj += ' (' + str(usedpnum) + '%)'
        msgbody = \
"""Warning! The disk space on the %s filesystem on %s is too high;
it is above the threshhold of %s percent:

""" % (watchfs, thishost, toofull)
        for line in alldf: msgbody += line
        msgbody += "\nThis message was automatically generated by: " + \
            os.path.abspath(sys.argv[0])
        msghead =  'From: ' + sender + "\n"
        msghead += 'To: ' + recip + "\n"
        msghead += 'Subject: ' + subj + "\n"
        message = msghead + "\n" + msgbody
        smtp.sendmail(sender, recip, message)