## machine info

[root@VIRTCENT11 ~]# cat /etc/redhat-release
CentOS release 5.6 (Final)

[root@VIRTCENT11 ~]# uname -a
Linux VIRTCENT11 2.6.18-194.el5xen #1 SMP Fri Apr 2 15:34:40 EDT 2010 x86_64 x86_64 x86_64 GNU/Linux

## nagios version

[root@VIRTCENT11 ~]# /usr/local/nagios/bin/nagios --version

Nagios Core 3.2.3
Copyright (c) 2009-2010 Nagios Core Development Team and Community Contributors
Copyright (c) 1999-2009 Ethan Galstad
Last Modified: 10-03-2010
License: GPL


## check_mysqllag plugin error

(Return code of 127 is out of bounds - plugin may be missing)

## here is the command definition

# check_mysql

define command{
        command_name    check_mysqllag
        command_line    $USER1$/check_mysqllag -H $HOSTADDRESS$ -p 3306 -v $ARG1$ $ARG2$
        }


## here is the service definition

define service{
        use                             generic-service         ; Name of service template to use
        hostgroup_name                  db-servers
        service_description             MySQL Lag
        check_command                   check_mysqllag
        notifications_enabled           0
        }





## check_mysqllag script

[root@virtcent10:/usr/local/nagios/libexec] #cat check_mysqllag
#! /bin/sh

STATE_OK=0
STATE_WARNING=1
STATE_CRITICAL=2
STATE_UNKNOWN=3
STATE_DEPENDENT=4
mysqlpath='/usr/bin/mysql'
warn=30
crit=60
null="NULL"
usage1="Usage: $0 -uroot -psecret [-w <warn>] [-c <crit>]"
usage2="<warn> is lag time, in seconds, to warn at.  Default is 30."
usage3="<crit> is lag time, in seconds, to be critical at.  Default is 60."

exitstatus=$STATE_WARNING #default
while test -n "$1"; do
    case "$1" in
        -c)
            crit=$2
            shift
            ;;
        -w)
            warn=$2
            shift
            ;;
        -u)
            user=$2
            shift
            ;;
        -p)
            pass=$2
            shift
            ;;
        -h)
            echo $usage1;
            echo
            echo $usage2;
            echo $usage3;
            exit $STATE_UNKNOWN
            ;;
        -H)
            host=$2
            shift
            ;;
        *)
            echo "Unknown argument: $1"
            echo $usage1;
            echo
            echo $usage2;
            echo $usage3;
            exit $STATE_UNKNOWN
            ;;
    esac
    shift
done

seconds=`$mysqlpath/mysql -u $user -p$pass -e 'show slave status\G' | /bin/grep Seconds_Behind_Master | /bin/cut -f2 -d:`

# on the number line, we need to test 6 cases:
# 0-----w-----c----->
# 0, 0<lag<w, w, w<lag<c, c, c<lag
# which we simplify to
# lag>=c, w<=lag<c, 0<=lag<warn

# if null, critical
if [ $seconds = $null ]; then
echo CRITICAL - Slave is $seconds seconds behind
exit $STATE_CRITICAL;
fi

#w<=lag<c
if [ $seconds -lt $crit ]; then
if [ $seconds -ge $warn ]; then
echo WARNING - Slave is $seconds seconds behind
exit $STATE_WARNING;
fi
fi

if [ $seconds -ge $crit ]; then
echo CRITICAL - Slave is $seconds seconds behind
exit $STATE_CRITICAL;
fi

# 0<=lag<warn
if [ $seconds -lt $warn ]; then
echo OK - Slave is $seconds seconds behind
exit $STATE_OK;
fi