The usual IT babble
Posts tagged Nagios 3
Custom macros in host definitions
Aug 16th
Well, I was playing with the hostgroup inheritance earlier. One problem with that is, if you define a duplicate service Nagios is really unpredictable or rather inconsistent. Now, as Thomas Guyot-Sionnest told me, I should try custom macros for the check definition. So what I did was the following:
templates/host-windows.cfg
define host {
name generic-windows
register 0
_RDPPORT 3389
}
hostgroups/windows.cfg
define hostgroup {
hostgroup_name windows
alias Windows Servers
hostgroup_members windows-terminal
}
define service {
use generic-service
check_command check_tcp!$_HOSTRDPPORT$
service_description RDP
hostgroup_name windows
}
hosts/terminal1.cfg
define host {
use generic-windows
host_name terminal1
alias terminal1.barfoo.org
address 10.0.0.250
parents barfoo-home
hostgroups windows-terminal
_RDPPORT 3390
}
As you can see, the default RDP port is 3389 (as defined in the host template), but for some systems you might want to “change” the port (for example, if you’re having a citrix farm and you changed the RDP port to something else and still want to be able to check whether or not the RDP service is active), thus the check using the macro, and a single host redefining the macro, thus having a bit more flexibility.
Nagios 3 and hostgroup inheritance
Aug 8th
As I wrote some time ago, I was trying to utilize Nagios 3.x’s neat feature of “nested” hostgroups. Well, as it turned out I thought it worked differently; basically like this:
define hostgroup {
hostgroup_name a-parent-hostgroup
alias Our toplevel parent hostgroup
}
define service {
use generic-service
check_command check_dummy!0!
service_description SSH
hostgroup_name a-parent-hostgroup
}
define hostgroup {
hostgroup_name a-child-hostgroup
hostgroup_members a-parent-hostgroup
alias Our child hostgroup
}
define service {
use generic-service
check_command check_dummy!0!
service_description LOAD
hostgroup_name a-child-hostgroup
}
As you can cleary see on line 14, I thought you define the relation between two hostgroups in the child hostgroup. The problem with it was basically (as I said in the earlier posts), that all the services defined for the child hostgroups are handed on upwards to the parent hostgroup(s).
But after talking to Tobi, I quickly found out, that the relation is in fact defined within the parent hostgroup. So if you simply put hostgroup_members within the parent hostgroup and define all child hostgroups which should inherit from the parent one, you should be just fine.
Nagios 3.x and check_pcmeasure.pl
Aug 7th
Recently we purchased a MessPC station for our server room, and my co-worker and myself had the wish it to be integrated within Nagios. Well, so far so good. The first I did was put both keywords into Google.
That pretty fast brought up the manufacturer’s page (sorry it’s German only) about the device supporting Nagios by means of either SNMP or a specific plugin called pcmeasure. So I went ahead and tried both ways.
Using SNMP has the advantage that it’s quickly integrated into Nagios and it doesn’t need a separate plugin for that to work. But it also has a huge disadvantage. check_snmp doesn’t support performance data, which is quite handy if you do want to do graphing from Nagios’ results.
Next I tried the pcmeasure plugin. At first it worked great (that is from plain command line), but then I tried to integrate it into Nagios (well, I did integrate it); but got “Plugin did not exit properly”.
Today, after I had the plugin commented out for about two weeks, I finally had time to look at the issue again. First I thought, simply using utils.pm’s error values would be sufficient for ePN to quit yapping, but apparently it had *real* problems with the pod2usage used within.
So I basically rewrote the plugin (well, not really; it’s still the same – but without the pod2usage and working in Nagios 3.0.3).
Nagios Hostgroup Inheritance (continued)
Jul 19th
Well, it turns out that my thought was ultimativly flawed. When defining the hostgroup_members in the lower tiers, nagios is association the checks from the lower tier with the upper tiers. Thus propagandating all checks upwards, and me ending up with ~250 checks instead of ~150.
Gonna have to try to define the dependency backwards, maybe that’ll help. But that’s a topic for Monday. Guess I’ll finish viewing Ghost in the Shell – Stand Alone Complex first.
Nagios Hostgroup Inheritance
Jul 17th
As I wrote earlier, I recently virtualized our nagios. Along with that came a complete “redesign” of how checks are applied. Up till now, I defined checks for each and every single server, thus ending up with ~25 files, each holding roughly 6 checks which are in the same file just sorted by hostname.
As you can imagine, it gets quite confusing with that amount of checks (~150). So the last two days I spent on reorganizing (with Visio), on which object/hostgroup placing a check would make sense. Now, this is my first result of two days planning, reorganizing, reordering and moving hosts into different hostgroups.
Nagios Hostgroup Inheritance - Linux
Nagios Hostgroup Inheritance - Windows
Thanks to Josh (and Chris I think), realizing the above is gonna get quite easy. Gonna talk about the config layout itself about once I have it all wrapped up. Stay tuned!