Munin contributed plugins

#!/usr/bin/perl -w

# Plugin to monitor offsets to multiple NTP peers.

# NB currently only works for IPv4 peers

#

# (c)2008 Chris Hastie: chris (at) oak (hyphen) wood (dot) co (dot) uk

#

# Parameters understood:

#

# 	config   (required)

# 	autoconf (optional - used by munin-node-configure)

#

# Config variables:

#

#       ntpq            - path to ntpq program

#       statedir        - directory in which to place state file

#       hostname_<key>  - override hostname for peer <key>. <key> is

#                         an IPv4 address with dots replaced by underscores.

#                         Useful for reference clocks, eg

#                         env.hostname_127_127_43_0  .GPS.

#

#

# 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 3 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, see <http://www.gnu.org/licenses/>.

#

# Change log

# v1.0.0    2008-07-21        Chris Hastie

# initial release 

#

#

#

# Magic markers - optional - used by installation scripts and

# munin-node-configure:

#

#%# family=contrib

#%# capabilities=autoconf

#

use strict;

use Socket;

my $NTPQ = $ENV{ntpq} || "ntpq";

my $COMMAND    =      "$NTPQ -np";

my $statedir = $ENV{statedir} || '/usr/local/var/munin/plugin-state';

my $statefile = "$statedir/ntp_peers.state";

# autoconf

if ($ARGV[0] and $ARGV[0] eq "autoconf") {

	`$NTPQ -c help >/dev/null 2>/dev/null`;

	if ($? eq "0") {

		if (`$NTPQ -np | wc -l` > 0) {

			print "yes\n";

			exit 0;

		} else {

			print "no (unable to list peers)\n";

			exit 1;

		}

	} else {

		print "no (ntpq not found)\n";

		exit 1;

	}

}

my %peers;

# retrieve cached list of IPs and hostnames

if (-f "$statefile") {

    open (IN, "$statefile") or exit 4;

    while (<IN>) {

      if (/^([0-9\.]+):(.*)$/) {

        $peers{$1}{'name'} = $2;

      }

    }

    close IN;

}

# do custom IP lookups

for my $key (map {/^hostname_(.+)/} keys %ENV) {

    my $ip = &desanitize_field($key);

    $peers{$ip}{'name'} = $ENV{"hostname_$key"}

}

# get data from ntpq

open(SERVICE, "$COMMAND |")

  or die("Could not execute '$COMMAND': $!");

while (<SERVICE>) {

    if (/^[-+*#](\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})(\s+\S+){7}\s+(\S+)/) {

      my $name  = &lookupname($1);

      $peers{$1}{'value'} = $3;      

    }

}

close(SERVICE);

# config

if ($ARGV[0] and $ARGV[0] eq 'config') {

  print "graph_title NTP peer offsets\n";

  print "graph_args --base 1000\n";

  print "graph_vlabel ms\n";

  print "graph_category ntp\n";

  print "graph_info Offset (in ms) to the server's NTP peers\n";

  print "graph_order ";

  foreach my $key (sort by_name keys %peers) {

    print &sanitize_field($peers{$key}{'name'}) . " ";

  }

  print "\n";

  foreach my $peer (keys %peers) {

    print &sanitize_field($peers{$peer}{'name'}) . ".label " . $peers{$peer}{'name'} . "\n";

  }

  exit 0;

}

# send output

foreach my $peer (keys %peers) {

  print &sanitize_field($peers{$peer}{'name'}) . ".value " . &getpeeroffset($peer) . "\n";

}

# save list of peer IPs and hostnames

if(-l $statefile) {

	die("$statefile is a symbolic link, refusing to touch it.");

}				

open (OUT, ">$statefile") or exit 4;

foreach my $i (keys %peers) {

  print OUT "$i:" . $peers{$i}{'name'} .  "\n";

}

close OUT;

# sorts by hostname

sub by_name {

	return $peers{$a}{'name'} cmp $peers{$b}{'name'};

}

# create a valid munin field name from the hostname

sub sanitize_field () {

  my $field = shift;

  # replace illegal characters with an underscore

  $field =~ s/[^A-Za-z0-9_]/_/g;

  # prepend an underscore if name starts with a number

  $field =~ s/^([^A-Za-z_])/_$1/;

  # truncate to 19 characters

  if (length($field) > 19) {

    $field = substr($field, 0, 19);

  }

  return $field

}

# get an IP address from the underscore escaped

# value of env.hostname_<key>

sub desanitize_field () {

  my $field = shift;

  $field =~ s/_/\./g;

  return $field

}

# lookup hostnames

sub lookupname () {

  my $ip = shift;

  # have we already got it?

  if ($peers{$ip}{'name'}) {

    return $peers{$ip}{'name'};    

  }

  # else look it up

  my $iaddr = inet_aton($ip); 

  my $name  = gethostbyaddr($iaddr, AF_INET) || $ip; 

  # add to cache

  $peers{$ip}{'name'} = $name;

  return $name;

}

# returns the offset, or U if it is undefined

sub getpeeroffset() {

  my $ip = shift;

  my $rtn = 'U';

  if (exists($peers{$ip}{'value'})) {

    $rtn = $peers{$ip}{'value'};

  }

  return $rtn

}

=pod

=head1 Description

ntp_peers - A munin plugin to monitor offsets to multiple NTP peers and

graph them on a single graph

=head1 Parameters understood:

  config   (required)

  autoconf (optional - used by munin-node-configure)

=head1 Configuration variables:

All configuration parameters are optional

  ntpq            - path to ntpq program

  statedir        - directory in which to place state file

  hostname_<key>  - override hostname for peer <key>. <key> is

                    an IPv4 address with dots replaced by underscores.

                    Useful for reference clocks, eg

                    env.hostname_127_127_43_0  .GPS.

=head1 Known issues

ntp_peers will not monitor IPv6 peers

=cut