Configuring holidays for Nagios

open up your nagios console

• Select Reports > Alerts > Summary
• Under Custom Report Options, Set Report Type to "Alert Totals" (or one of the options like this for finer grained reporting
• Set the Report Period to "* CUSTOM REPORT PERIOD *"
• Set the start date and end dates appropriately
• Apply any other filters that you would like (hostgroups, hosts etc)
• It is not necessary to adjust Max List Items as this report is quite short.
• Click on Create Summary Report

Done!

This is valid for Nagios 3.2.0

What you want in this case is not dependencies (as Nagios calls them), but rather you want parent/child relationships in your hosts. If the parent is down and children can not be reached Nagios considers them "unreachable" instead of "down". You can then configure not to be notified if things are "unreachable". You can read more about this in the Nagios documentation here.

Also, from the same section of the 2.0 documentation it is pointed out that services won't alert if the host is down (saving you those alerts):

Whenever a service check results in a non-OK status level, Nagios will attempt to check and see if the host that the service is running on is "alive". Typically this is done by pinging the host and seeing if any response is received. If the host check command returns a non-OK state, Nagios assumes that there is a problem with the host. In this situation Nagios will "silence" all potential alerts for services running on the host and just notify the appropriate contacts that the host is down or unreachable. If the host check command returns an OK state, Nagios will recognize that the host is alive and will send out an alert for the service that is misbehaving.

Service dependencies by default are not inheritable from a host template, but I believe the parent is. So you can inherit parents from templates (if I am correct in this) and save yourself some typing.

Lastly, I actually like to have unreachable alerts enabled. If the router goes down, I want my phone to go "nuts". :-)