Hidden/unvisible hostgroups or service-sets - how to use


The "hidden hostgroup" easter egg implemented in Nagios 4 means you canuse hostgroups which have "register 0" to assign services to. It was originally an idea by Christian Anton but got implemented by accident during the Nagios 4.0 config revamp as a side effect of the optimisations. Basically, it means that you can create a config like this;

define hostgroup {  hostgroup_name      _sset_pop3server  # register 0 means this never shows up in the UI  register            0} define service {  use                 some-random-service-template  check_command  check_pop3!$host:_SSETPOP3WARN$!$host:_SSETPOP3CRIT$  service_description POP3 service} define host {  use some-random-host-template  host_name pop3server  hostgroups _sset_pop3server  _SSETPOP3WARN  10  _SSETPOP3CRIT  20}

and things will just work.

Note: In order to get any kind of performance out of using this on a larger-than-pretty-small scale, it's necessary to implement some caching in Nagios so most command macros are only resolved once instead of every time. There's a plan for that, and it can be implemented pretty quickly.

The (very loose) idea is to add some sort of support for this in Nacoma. Possibly by converting existing "host profiles" or by using the already-coined term "service sets" and build basic monitoring for particular types of equipment (such as ms-nsclient, unix-nrpe, server-snmp, vmware-guest etc, etc).

The long-term idea is still to implement "callable" service sets, where one can do things like:

define host {  host_name MS Exchange 1  service_set msexchange(warn=10,crit=20,sendqwarn=1000)} define serviceset {  serviceset_name mail-server  define service {    service_description POP3 service    check_command  check_pop3!%{warn}!%{crit}  }  define service {    service_description SMTP service    check_command $PLUGIN_DIR$/check_smtp!%{warn}!%{crit}  }} define serviceset {  serviceset_name ms-exchange  includes mail-server  define service {    service_description MSExchange SendQ    check_command $PLUGIN_DIR$/check_nsclient!%{sendqwarn}  }}

although it's possible we'll make a special prefix (sset_) for hosts to allow them to pass variables to service-sets as well. If you want to make servicesets right now, please utilize the _sset prefix for custom variables for hosts. Use the same prefix for hostgroup_names, and use _service_set "somename" for services you want included in the set. That will allow us to automatically manage service sets.

The UI honey on top of the Nagios syntax voodoo will most likely be delivered in 6.2 in some form or other, even if it appears as a fairly simple hack.