The "hidden hostgroup" easter egg implemented in Nagios 4 means you can
use hostgroups which have "register 0" to assign services to. It was
originally an idea by Christian Anton actually (waaaay back, afair),
but got implemented by accident during the Nagios 4.0 config revamp
as a sideeffect of the optimizations.
Basically, it means that you can create a config like this;
and things will just work.
Note that 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
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
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 automagically
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.