Nagios: SNMP checks for a Synology Diskstation

Because Synology uses embedded linux it is difficult to get the nagios-plugins package installed to do nrpe monitoring.  I tried the ipkg method then building the nagios-plugins from source, and while that site was helpful, I kept getting compile errors, probably a missing or outdated library issue.  That is OK because nagios has SNMP checks, and going one step further, has community plugins for Synology.  We are going to be using this community plugin from the user deegan199.

First we need to enable SNMP.  In DSM 5.x open the control panel and browse to Terminal & SNMP then the SNMP tab:

And that is all for the synology, no ports to open nor restart needed.

Grab the synology snmp check from the previous link and throw it into your plugins folder.  You may need to change the permissions to executable for your nagios user, something like:

 # chmod +x check_snmp_synology  

If this is your first SNMP check for nagios, you need the snmpget and snmpwalk programs, in redhat/centos get them from the net-snmp-utils package:

 # yum install net-snmp-utils  

Next run the plugin from your nagios server to do a test, change -h for your Synology's IP address:

 # ./check_snmp_synology -h 192.168.1.30 -v  

Next we will set up our nagios configs to get this check on the nagios panel.  First we will add the synology command definition to our commands.cfg:

 ################################################################################  
 #  
 # SYNOLOGY  
 #  
 ################################################################################  
 define command{  
      command_name check_synology  
      command_line /usr/lib64/nagios/plugins/check_snmp_synology -h $HOSTADDRESS$ -v  
 }  

I am leaving the -v (verbose) switch in because its nice to have the entire output on the Nagios panel, its up to you.  Next create a config for your Synology device inside your nagios/etc/servers directory and assign this new command to it, I also added SSH, for the heck of it:

 ###############################################################################  
 ###############################################################################  
 #  
 # HOST DEFINITION  
 #  
 ###############################################################################  
 ###############################################################################  
 define host{  
     use            linux-server      ; Name of host template to use  
     host_name      synology1
     alias          synology1
     address        192.168.1.30  
     }  
 ###############################################################################  
 ###############################################################################  
 #  
 # SERVICE DEFINITIONS  
 #  
 ###############################################################################  
 ###############################################################################  
 define service{  
   use                  generic-service  
   host_name            synology1
   service_description      System Health  
   check_command        check_synology  
   }  
 define service{  
   use                  generic-service  
   host_name            synology1
   service_description      SSH  
   check_command        check_ssh  
   }  

Save and do a service nagios restart and soon you will have your checks in your Nagios panel:

Initialized Disks
If your Synology is provisioned with hot-spares then Synology reports the disks as "initialized" and this plugin will create a critical alert for these initialized disks.  This was the case for one of my Synology devices, luckily in the comments for this plugin user mtominsk provides a fix.  Change the following in the check_snmp_synology plugin:

Original:

 if [ "${diskStatus[$i]}" != "1" ] ; then  
         if [ "${diskStatus[$i]}" = "2" ] ; then    diskStatus[$i]="Initialized";            fi  
     if [ "${diskStatus[$i]}" = "3" ] ; then    diskStatus[$i]="NotInitialized";        fi  
     if [ "${diskStatus[$i]}" = "4" ] ; then    diskStatus[$i]="SystemPartitionFailed";        fi  
     if [ "${diskStatus[$i]}" = "5" ] ; then    diskStatus[$i]="Crashed";            fi  
         healthStatus=2  
         healthString="$healthString, problem with ${diskID[$i]} (model:${diskModel[$i]}) status:${diskStatus[$i]} temperature:${diskTemp[$i]} C "  
 else  
     diskStatus[$i]="Normal"  
     fi  
     if [ "$verbose" = "yes" ] ; then  echo "${diskID[$i]} (model:${diskModel[$i]}) status:${diskStatus[$i]} temperature:${diskTemp[$i]} C" ; fi  
 done  

Modified:

 if [ "${diskStatus[$i]}" != "1" ] && [ "${diskStatus[$i]}" != "2" ] ; then  
     # if [ "${diskStatus[$i]}" = "2" ] ; then diskStatus[$i]="Initialized"; fi  
     if [ "${diskStatus[$i]}" = "3" ] ; then diskStatus[$i]="NotInitialized"; fi  
     if [ "${diskStatus[$i]}" = "4" ] ; then diskStatus[$i]="SystemPartitionFailed"; fi  
     if [ "${diskStatus[$i]}" = "5" ] ; then diskStatus[$i]="Crashed"; fi  
         healthStatus=2  
         healthString="$healthString, problem with ${diskID[$i]} (model:${diskModel[$i]})   status:${diskStatus[$i]} temperature:${diskTemp[$i]} C "  
 elif [ "${diskStatus[$i]}" = "2" ] ; then diskStatus[$i]="Initialized";  
 else  
     diskStatus[$i]="Normal"  
     fi  
     if [ "$verbose" = "yes" ] ; then echo "${diskID[$i]} (model:${diskModel[$i]}) status:${diskStatus[$i]} temperature:${diskTemp[$i]} C" ; fi  
 done  

Brilliant!  Thanks deegan199 and mtominsk!

Nagios: A linux disk space check that matches the default Window disk space check.

Pretty:

Not so pretty:

The first one is a Windows Server VM with the default disk check from NSClient++, the second is a CentOS VM with the default check_disk from the yum nagios-plugins package.  Which one tells me more info?

Looking for a linux check disk plugin that can give me more info I came across this plugin by radumar1001 on the Nagios Exchange.  Lets change up our nrpe check on the CentOS vm to use it and see what it looks like.

First download the plugin and drop it on your linux client in your plugins folder, in my case it is /usr/lib64/nagios/plugins but yours might be different.  Next you need to change the plugin permissions so your root or nagios user can run it:

Next browse to the location of nrpe.cfg (/etc/nagios in my case) and open it up in your favorite editor.  In my case I am already using the default check_disk plugin like so:

 command[check_disk]=/usr/lib64/nagios/plugins/check_disk --units GB -M -w 20% -c 10% -p /dev/mapper/vg_centos-lv_root  

What we will do is modify this so we check check_disk_space instead.  It has three requirements, a warning threshold and a critical threshold, both of which are defined by USED space and a third to define which partition to check.  Comment out the old check, or modify it so it looks something like this:

 command[check_disk]=/usr/lib64/nagios/plugins/check_disk_space -w 80 -c 90 -p /  

Save it and since we changed nrpe.cfg we need to restart nrpe on the client by using service nrpe restart.  Since we did not need to change any configs on the nagios server, there is no need to restart Nagios on it.  Once Nagios runs that check again we will have a nicely formatted disk check:

Very pretty!

Resources

• the linux check_disk_space plugin