MonitorDRBDdeviceswithnagios

install

on all ganeti nodes

just install check_drbd (http://www.monitoringexchange.org/p_w_upload/download/Check-Plugins/Operating-Systems/Linux/check_drbd/check_drbd) somewhere in the path.  

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By default, this script will return CRITICAL if a device is unconfigured, and UNKNOWN if a device does not exists. These situations can happen with ganeti when :

- a vm is down  

- a vm is down and a node has been rebooted (then the drbd device disappears).  

You may want to patch check_drbd like this to avoid "false" alerts :

--- check_drbd  2010-01-2609:10:16.000000000+0100
+++/usr/local/bin/check_drbd  2010-01-2609:06:23.000000000+0100
@@-38,7+38,7@@
'WFConnection'=>{'value'=>'CRITICAL','type'=>'cs'},
'WFReportParams'=>{'value'=>'CRITICAL','type'=>'cs'},
'Connected'=>{'value'=>'OK','type'=>'cs'},
-'Unconfigured'=>{'value'=>'CRITICAL','type'=>'cs'},
+'Unconfigured'=>{'value'=>'OK','type'=>'cs'},
# DRBD 0.6
'SyncingAll'=>{'value'=>'WARNING','type'=>'cs'},
'SyncingQuick'=>{'value'=>'WARNING','type'=>'cs'},
@@-261,7+261,7@@
}
foreachmy $device(@devices){
if(!(defined($cs{$device}))){
-&myexit('UNKNOWN',"Could not find device $device");
+&myexit('OK',"Could not find device $device");
}
               $check{$device}=1;
}

on ganeti master

put this script somewhere in the path (/usr/local/bin/drbd_gen_nagios.sh for ex):  

#!/bin/bash
#
# Copyright (C) 2009 Maxence Dunnewind 
#
# 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 .

gnt-instance list  --no-header--separator=:-o name|while read vm;do
       TMP_FILE=$(mktemp)
       gnt-instance info-s $vm> $TMP_FILE 
       NODE_A=$(grep"nodeA" $TMP_FILE|grep-o"[^ ]\+,"|head-1|sed 
's/,//')
       NODE_B=$(grep"nodeB" $TMP_FILE|grep-o"[^ ]\+,"|head-1|sed 
's/,//')
       DEV_A=$(grep"nodeA" $TMP_FILE|cut-d"="-f2)
       DEV_B=$(grep"nodeB" $TMP_FILE|cut-d"="-f2)
       rm-rf $TMP_FILE 
for diskin $DEV_A;do
               echo"define service {"
               echo" host_name                $NODE_A"
               echo" service_description      DRBD instance $vm / 
device n° $disk"
               echo" check_command            check_drbd!$disk"
               echo" use                      generic-service"
               echo"}"
               echo""
done
for diskin $DEV_B;do
               echo"define service {"
               echo" host_name                $NODE_B"
               echo" service_description      DRBD instance $vm / 
device n° $disk"
               echo" check_command            check_drbd!$disk"
               echo" use                      generic-service"
               echo"}"
               echo""
done
done

Important: This script only define drbd checks, so you already need  to have the hosts configured in your nagios.  

on nagios

Define check_drbd, which will use check_by_ssh to call check_drbd  script on the nodes.  

define command{
       command_name    check_drbd 
       command_line    /usr/lib/nagios/plugins/check_by_ssh-H $HOSTADDRESS$-l root-C"/usr/local/bin/check_drbd -d $ARG1$"
}

for example in /etc/nagiosX/conf.d/command.cfg .

Also, be sure nagios user can connect using ssh without password. If you don't have defined that, you need to :

# su - nagios
# ssh-keygen
Generatingpublic/private rsa key pair.
Enter filein which to save the key(/var/run/nagios3/.ssh/id_rsa):/etc/nagios3/id_rsa
Enter passphrase(emptyforno passphrase):
Enter same passphrase again:

Don't forget to replace the file. If you keep /var/run, your key will be deleted after next reboot :) Also, keep the passphrase empty. Then, copy the id_rsa.pub under /root/.ssh/authorized_keys on all your hosts. You can also add a "from" field and a "command" one to limit access :  

from="1.1.1.1",command="/usr/local/bin/check_drbd" ssh-rsa AAAAB3NzaC1yc2EAAAABIwA...

Use

To generate the config, after a new instance has been added / removed, or after a replace-disks, run :  

drbd_gen_nagios.sh> drbd.cfg

on ganeti master, then just copy the generated file into your nagios  conf.d directory, and check the config / restart your nagios.