2.0 Nagios CVS - Service Dependencies Patch - bug fixes and new features
Ethan Galstad
nagios at nagios.org
Tue Apr 20 06:34:03 CEST 2004
Hi Karl -
I'm a bit behind on applying some of the patches recently submitted
to the list, but hope to have this incorporated into CVS by the end
of the week.
On 19 Apr 2004 at 18:28, Mueller, Karl wrote:
> Hello All,
>
> I wrote a few weeks ago the list asking some questions about service
> dependencies, because the way they are currently defined, I find them
> very hard to use for our typical needs. A typical example is an
> Oracle SQL check which does something (perhaps checks redo log
> status). It should not run the check if Oracle is down, right?
> Service dependencies to the rescue! Unfortunately, if you have a
> large group of host - we have 50 in this group, for example - you
> can't tell Nagios that every Oracle Redo Log check depends on its OWN
> Oracle check without defining 50 service dependencies. That is a
> pain, and we probably have 6 or 7 dependencies on each host on its own
> services, if not more.
>
> Instead of writing some kind of configuration script to do this for
> me, I decided to just write a patch to do it. There are two main
> features to the patch:
>
> 1) If a "host_name" entry in a servicedependency definition is "SELF"
> (any capitalization), then every host in the host_name, host_group, or
> service_group line will receive a dependency instance against ITSELF
> ONLY with the appropriate service name. An example configs:
>
> ####
> #### Depend on 'Oracle' service on our own service
> ####
>
>
> define servicedependency {
>
> use defaults
>
> dependent_service_description Oracle Failed Logins
> dependent_hostgroup_name s_prod_oracle
>
> service_description Oracle
> host_name SELF
>
> }
>
> This creates dependencies for every host in "s_prod_oracle" on ITSELF
> for the "Oracle Failed Logins" service on the "Oracle" service. It's
> exactly the same as if you took every host in "s_prod_oracle" and
> defined a servicedependency object with its own host_name in it. ('N'
> objects)
>
> 2) Something similar, but slightly different: if you set a new config
> variable "peer_groups", indicating that the two groups you're going to
> specify are "peers" to each other, Nagios will create one to one
> dependencies instead of many to many dependencies. Example:
>
>
> define servicedependency {
>
> use defaults
>
> dependent_service_description Oracle Failed Logins
> dependent_hostgroup_name s_prod_oracle
>
> service_description Oracle
> host_name s_prod_oracle
>
> peer_groups 1
>
> }
>
> Is functionally equivilant to the first example. If you have:
>
> dependent_host_name A, B, C, D
> host_name M, N, O, P
>
> Nagios would *normally* create dependencies: "A:M, A:N, A:O, A:P, B:M,
> B:N...", etc.
>
> With "peer_groups" enabled, Nagios will now create: "A:M, B:N, C:O,
> D:P" ONLY.
>
> Of course, with this option set, the number of hosts that are
> eventually resolved from expansion of hostgroup(s)/servicegroup(s)
> MUST BE EQUAL.
>
> How is this useful? Besides creating "self" dependencies as above
> (which are better handled through 'self'), you can reverse the group
> names or hosts, etc., to do some interesting things.
>
> 3) Fixes a bug where inherits_parent was not initialized in
> xodtemplate_duplicate_servicedependency() in xodtemplate.c
>
>
> 4) Fixes a bug where value of inherits_parent() was not verified to be
> 0 or 1 (hiding bug #3 while I was verifying this patch :( )
> (objects.c)
>
> The patch is located at, and is made against the 2.0 CVS tree as of
> today:
>
> http://www.xney.com/nagios/nagios-2.0-servicedep.patch
>
>
> I have tested this patch in positive and negative cases, but I'd love
> to hear if people could use it and have verified it works (or doesn't
> break anything).
>
> -Karl
>
>
>
>
>
>
>
>
>
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Ethan Galstad,
Nagios Developer
---
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