#!/usr/bin/env python
"""Nagios plugin to test for Yum updates on RedHat/CentOS Linux.
Can optionally alert on any available updates as well as just
security related updates"""
__author__ = "Hari Sekhon"
__title__ = "Nagios Plugin for Yum updates on RedHat/CentOS systems"
__version__ = "0.7.1"
# Standard Nagios return codes
OK = 0
WARNING = 1
CRITICAL = 2
UNKNOWN = 3
import os
import re
import sys
import signal
OLD_PYTHON = False
try:
from subprocess import Popen, PIPE, STDOUT
except ImportError:
OLD_PYTHON = True
import commands
from optparse import OptionParser
DEFAULT_TIMEOUT = 30
def end(status, message):
"""Exits the plugin with first arg as the return code and the second
arg as the message to output"""
check = "YUM "
if status == OK:
print "%sOK: %s" % (check, message)
sys.exit(OK)
elif status == WARNING:
print "%sWARNING: %s" % (check, message)
sys.exit(WARNING)
elif status == CRITICAL:
print "%sCRITICAL: %s" % (check, message)
sys.exit(CRITICAL)
else:
print "UNKNOWN: %s" % message
sys.exit(UNKNOWN)
YUM = "/usr/bin/yum"
def check_yum_usable():
"""Checks that the YUM program and path are correct and usable - that
the program exists and is executable, otherwise exits with error"""
if not os.path.exists(YUM):
end(UNKNOWN, "%s cannot be found" % YUM)
elif not os.path.isfile(YUM):
end(UNKNOWN, "%s is not a file" % YUM)
elif not os.access(YUM, os.X_OK):
end(UNKNOWN, "%s is not executable" % YUM)
class YumTester:
"""Class to hold all portage test functions and state"""
def __init__(self):
"""Initialize all object variables"""
self.all_updates = False
self.no_cache_update = False
self.no_warn_on_lock = False
self.enable_repo = ""
self.disable_repo = ""
self.timeout = DEFAULT_TIMEOUT
self.verbosity = 0
self.warn_on_any_update = False
def validate_all_variables(self):
"""Validates all object variables to make sure the
environment is sane"""
if self.timeout == None:
self.timeout = DEFAULT_TIMEOUT
try:
self.timeout = int(self.timeout)
except ValueError:
end(UNKNOWN, "Timeout must be an whole number, " \
+ "representing the timeout in seconds")
if self.timeout < 1 or self.timeout > 3600:
end(UNKNOWN, "Timeout must be a number between 1 and 3600 seconds")
if self.verbosity == None:
self.verbosity = 0
try:
self.verbosity = int(self.verbosity)
if self.verbosity < 0:
raise ValueError
except ValueError:
end(UNKNOWN, "Invalid verbosity type, must be positive numeric " \
+ "integer")
def run(self, cmd):
"""runs a system command and returns
an array of lines of the output"""
if cmd == "" or cmd == None:
end(UNKNOWN, "Internal python error - " \
+ "no cmd supplied for run function")
if self.no_cache_update:
cmd += " -C"
if self.enable_repo:
for repo in self.enable_repo.split(","):
cmd += " --enablerepo=%s" % repo
if self.disable_repo:
for repo in self.disable_repo.split(","):
cmd += " --disablerepo=%s" % repo
self.vprint(3, "running command: %s" % cmd)
if OLD_PYTHON:
self.vprint(3, "subprocess not available, probably old python " \
+ "version, using shell instead")
returncode, stdout = commands.getstatusoutput(cmd)
if returncode >= 256:
returncode = returncode / 256
else:
try:
process = Popen( cmd.split(),
stdin=PIPE,
stdout=PIPE,
stderr=STDOUT )
except OSError, error:
error = str(error)
if error == "No such file or directory":
end(UNKNOWN, "Cannot find utility '%s'" % cmd.split()[0])
end(UNKNOWN, "Error trying to run utility '%s' - %s" \
% (cmd.split()[0], error))
output = process.communicate()
returncode = process.returncode
stdout = output[0]
if stdout == None or stdout == "":
end(UNKNOWN, "No output from utility '%s'" % cmd.split()[0])
self.vprint(3, "Returncode: '%s'\nOutput: '%s'" \
% (returncode, stdout))
output = str(stdout).split("\n")
self.check_returncode(returncode, output)
return output
def check_returncode(self, returncode, output):
"""Takes the returncode and output (as an array of lines)
of the yum program execution and tests for failures, exits
with an appropriate message if any are found"""
if returncode == 0:
pass
elif returncode == 100:
# Updates Available
pass
elif returncode == 200:
if "lock" in output[-2] or "another copy is running" in output[-2]:
msg = "Cannot check for updates, " \
+ "another instance of yum is running"
if self.no_warn_on_lock:
end(OK, msg)
else:
end(WARNING, msg)
else:
output = self.strip_output(output)
end(UNKNOWN, "%s" % output)
else:
if not 'Loading "security" plugin' in output \
or "Command line error: no such option: --security" in output:
end(UNKNOWN, "Security plugin for yum is required. Try to " \
+ "'yum install yum-security' and then re-run " \
+ "this plugin. Alternatively, to just alert on " \
+ "any update which does not require the security " \
+ "plugin, try --all-updates")
else:
output = self.strip_output(output)
end(UNKNOWN, "%s" % output)
def strip_output(self, output):
"""Cleans up the output from the plugin and returns it.
Takes and returns an array of the lines of output
and returns a single string"""
self.vprint(3, "stripping output of 'Loading ... plugin' lines")
re_loading_plugin = re.compile("^Loading .+ plugin$")
output = [re_loading_plugin.sub("", line) for line in output]
output = " ".join(output).strip()
return output
def set_timeout(self):
"""sets an alarm to time out the test"""
if self.timeout == 1:
self.vprint(3, "setting plugin timeout to %s second" \
% self.timeout)
else:
self.vprint(3, "setting plugin timeout to %s seconds"\
% self.timeout)
signal.signal(signal.SIGALRM, self.sighandler)
signal.alarm(self.timeout)
def sighandler(self, discarded, discarded2):
"""Function to be called by signal.alarm to kill the plugin"""
# Nop for these variables
discarded = discarded2
discarded2 = discarded
end(CRITICAL, "Yum nagios plugin has self terminated after " \
+ "exceeding the timeout (%s seconds)" % self.timeout)
def get_updates(self):
"""Checks for updates and returns a tuple containing the number of
security updates and the number of total updates"""
self.vprint(2, "checking for any security updates")
if self.all_updates:
number_security_updates, number_other_updates = \
self.get_all_updates()
else:
number_other_updates = self.get_security_updates()
number_security_updates = 0
return number_security_updates, number_other_updates
def get_all_updates(self):
"""Gets all updates. Returns a single integer of the
number of available updates"""
cmd = "%s check-update" % YUM
output = self.run(cmd)
output2 = "\n".join(output).split("\n\n")
if self.verbosity >= 4 :
for section in output2:
print "\nSection:\n%s\n" % section
if len(output2) > 2 or \
not ( "Setting up repositories" in output2[0] or \
"Loaded plugins: " in output2[0] or \
re.search('Loading\s+".+"\s+plugin', output2[0]) ):
end(WARNING, "Yum output signature does not match current known " \
+ "format. Please make sure you have upgraded to the " \
+ "latest version of this plugin. If the problem " \
+ "persists, please contact the author for a fix")
if len(output2) == 1:
# There are no updates but we have passed
# the loading and setting up of repositories
number_packages = 0
else:
number_packages = len([x for x in output2[1].split("\n") \
if len(x.split()) > 1 ])
try:
number_packages = int(number_packages)
if number_packages < 0:
raise ValueError
except ValueError:
end(UNKNOWN, "Error parsing package information, invalid package " \
+ "number, yum output may have changed. Please make " \
+ "sure you have upgraded to the latest version of " \
+ "this plugin. If the problem persists, then please " \
+ "contact the author for a fix")
# Extra layer of checks. This is a security plugin so it's preferable
# to fail on error rather than pass silently leaving you with an
# insecure system
count = 0
re_package_format = \
re.compile("^.+\.(i[3456]86|x86_64|noarch)\s+.+\s+.+$")
# This is to work around a yum truncation issue effectively changing
# the package output format. Currently only very long kmod lines
# are seen to have caused this so we stick to what we know for safety
# and raise an unknown error on anything else for maximum security
#re_package_format_truncated = \
# re.compile("^[\w-]+-kmod-\d[\d\.-]+.*\s+.+\s+.+$")
for line in output:
if re_package_format.match(line):
count += 1
if count != number_packages:
end(UNKNOWN, "Error parsing package information, inconsistent " \
+ "package count, yum output may have changed. Please " \
+ "make sure you have upgraded to the latest version " \
+ "of this plugin. If the problem persists, then " \
+ "please contact the author for a fix")
return number_packages
def get_security_updates(self):
"""Gets all updates, but differentiates between
security and normal updates. Returns a tuple of the number
of security and normal updates"""
cmd = "%s --security check-update" % YUM
output = self.run(cmd)
re_security_summary = \
re.compile("Needed \d+ of \d+ packages, for security")
re_no_security_updates_available = \
re.compile("No packages needed, for security, \d+ available")
summary_line_found = False
for line in output:
if re_no_security_updates_available.match(line):
summary_line_found = True
number_security_updates = 0
number_total_updates = line.split()[5]
break
elif re_security_summary.match(line):
summary_line_found = True
number_security_updates = line.split()[1]
number_total_updates = line.split()[3]
break
if not summary_line_found:
end(WARNING, "Cannot find summary line in yum output. Please " \
+ "make sure you have upgraded to the latest version " \
+ "of this plugin. If the problem persists, please " \
+ "contact the author for a fix")
try:
number_security_updates = int(number_security_updates)
number_total_updates = int(number_total_updates)
except ValueError:
end(WARNING, "Error parsing package information, yum output " \
+ "may have changed. Please make sure you have " \
+ "upgraded to the latest version of this plugin. " \
+ "If the problem persists, the please contact the " \
+ "author for a fix")
number_other_updates = number_total_updates - number_security_updates
if len(output) > number_total_updates + 25:
end(WARNING, "Yum output signature is larger than current known " \
+ "format, please make sure you have upgraded to the " \
+ "latest version of this plugin. If the problem " \
+ "persists, please contact the author for a fix")
return number_security_updates, number_other_updates
def test_yum_updates(self):
"""Starts tests and controls logic flow"""
check_yum_usable()
self.vprint(3, "%s - Version %s\nAuthor: %s\n" \
% (__title__, __version__, __author__))
self.validate_all_variables()
self.set_timeout()
if self.all_updates:
return self.test_all_updates()
else:
return self.test_security_updates()
def test_all_updates(self):
"""Tests for all updates, and returns a tuple
of the status code and output"""
status = UNKNOWN
message = "code error - please contact author for a fix"
number_updates = self.get_all_updates()
if number_updates == 0:
status = OK
message = "0 Updates Available"
else:
status = CRITICAL
if number_updates == 1:
message = "1 Update Available"
else:
message = "%s Updates Available" % number_updates
return status, message
def test_security_updates(self):
"""Tests for security updates and returns a tuple
of the status code and output"""
status = UNKNOWN
message = "code error - please contact author for a fix"
number_security_updates, number_other_updates = \
self.get_security_updates()
if number_security_updates == 0:
status = OK
message = "0 Security Updates Available"
else:
status = CRITICAL
if number_security_updates == 1:
message = "1 Security Update Available"
elif number_security_updates > 1:
message = "%s Security Updates Available" \
% number_security_updates
if number_other_updates != 0:
if self.warn_on_any_update == True and status != CRITICAL:
status = WARNING
if number_other_updates == 1:
message += ". 1 Non-Security Update Available"
else:
message += ". %s Non-Security Updates Available" \
% number_other_updates
return status, message
def vprint(self, threshold, message):
"""Prints a message if the first arg is numerically greater than the
verbosity level"""
if self.verbosity >= threshold:
print "%s" % message
def main():
"""Parses command line options and calls the test function"""
tester = YumTester()
parser = OptionParser()
parser.add_option( "--all-updates",
action="store_true",
dest="all_updates",
help="Does not distinguish between security and " \
+ "non-security updates, but returns critical for " \
+ "any available update. This may be used if the " \
+ "yum security plugin is absent or you want to " \
+ "maintain every single package at the latest " \
+ "version. You may want to use " \
+ "--warn-on-any-update instead of this option")
parser.add_option( "--warn-on-any-update",
action="store_true",
dest="warn_on_any_update",
help="Warns if there are any (non-security) package " \
+ "updates available. By default only warns when " \
+ "security related updates are available. If " \
+ "--all-updates is used, then this option is " \
+ "redundant as --all-updates will return a " \
+ "critical result on any available update, " \
+ "whereas using this switch still allows you to " \
+ "differentiate between the severity of updates ")
parser.add_option( "-C",
"--cache-only",
action="store_true",
dest="no_cache_update",
help="Run entirely from cache and do not update the " \
+ "cache when running yum. Useful if you have " \
+ "'yum makecache' cronned so that the nagios " \
+ "check itself doesn't have to do it, possibly " \
+ "speeding up execution (by 1-2 seconds in tests)")
parser.add_option( "--no-warn-on-lock",
action="store_true",
dest="no_warn_on_lock",
help="Return OK instead of WARNING when yum is locked " \
+ "and fails to check for updates due to another " \
+ "instance running. This is not recommended from " \
+ "the security standpoint, but may be wanted to " \
+ "reduce the number of alerts that may " \
+ "intermittently pop up when someone is running " \
+ "yum interactively for package management")
parser.add_option( "--enablerepo",
dest="repository_to_enable",
help="Explicitly enables a reposity when calling yum. "
+ "Can take a comma separated list of repositories")
parser.add_option( "--disablerepo",
dest="repository_to_disable",
help="Explicitly disables a repository when calling yum "
+ "Can take a comma separated list of repositories")
parser.add_option( "-t",
"--timeout",
dest="timeout",
help="Sets a timeout in seconds after which the " \
+"plugin will exit (defaults to %s seconds). " \
% DEFAULT_TIMEOUT)
parser.add_option( "-v",
"--verbose",
action="count",
dest="verbosity",
help="Verbose mode. Can be used multiple times to " \
+ "increase output. Use -vvv for debugging output. " \
+ "By default only one result line is printed as " \
+ "per Nagios standards")
parser.add_option( "-V",
"--version",
action="store_true",
dest="version",
help="Print version number and exit")
(options, args) = parser.parse_args()
if args:
parser.print_help()
sys.exit(UNKNOWN)
tester.all_updates = options.all_updates
tester.no_cache_update = options.no_cache_update
tester.no_warn_on_lock = options.no_warn_on_lock
tester.enable_repo = options.repository_to_enable
tester.disable_repo = options.repository_to_disable
tester.timeout = options.timeout
tester.verbosity = options.verbosity
tester.warn_on_any_update = options.warn_on_any_update
if options.version:
print "%s - Version %s\nAuthor: %s\n" \
% (__title__, __version__, __author__)
sys.exit(OK)
result, output = tester.test_yum_updates()
end(result, output)
if __name__ == "__main__":
try:
main()
except KeyboardInterrupt:
print "Caught Control-C..."
sys.exit(CRITICAL)