Puppet and Nagios: a Roadmap to Advanced Configuration

Listing 5. modules/nagios/manifests/resource/file.pp

define nagios::resource::file(
  $resource_tag,
  $requires,
  $export = true,
  $ensure = 'present',
) {

  include nagios::params

  if $export {

    @@file { $name:
      ensure => $ensure,
      tag => $resource_tag,
      owner => $nagios::params::user,
      require => $requires,
    }
  } else {

    file { $name:
      ensure => $ensure,
      tag => $resource_tag,
      owner => $nagios::params::user,
      require => $requires,
    }
  }
}

Listing 6. modules/nagios/manifests/resource/host.pp

define nagios::resource::host(
  $address,
  $hostgroups,
  $export,
  $target,
  $check_command,
  $use,
  $ensure = 'present'
) {

  include nagios::params

  if $export {

    @@nagios_host { $name:
      ensure => $ensure,
      address => $address,
      check_command => $check_command,
      use => $use,
      target => $target,
      hostgroups => $hostgroups ? {
        '' => undef,
        default => $hostgroups,
      },
    }
  } else {

    nagios_host { $name:
      ensure => $ensure,
      address => $address,
      check_command => $check_command,
      use => $use,
      target => $target,
      require => File[$nagios::params::resource_dir],
      hostgroups => $hostgroups ? {
        '' => undef,
        default => $hostgroups,
      },
    }
  }
}

Listing 7. modules/nagios/manifests/resource/hostgroup.pp

define nagios::resource::hostgroup(
  $target,
  $ensure = 'present',
  $hostgroup_alias = '',
  $export = false
) {

  include nagios::params

  if $export {
    fail("It is not appropriate to export the Nagios_hostgroup 
↪type since it will result in duplicate resources.")
  } else {
    nagios_hostgroup { $name:
      ensure => $ensure,
      target => $target,
      require => File[$nagios::params::resource_dir],
    }
  }
}

Listing 8 shows our refactored nagios::export class that is meant to be used by all nodes. Notice how we no longer leverage the nagios_host type directly. Instead, we call upon our newly created nagios::resource definition. Both the address and hostgroups parameters will use sane defaults unless they are overridden with node scoped variables. Also, notice how the target parameter is no longer required, as our nagios::resource definition performs the heavy lifting for us.

Listing 8. modules/nagios/manifests/export.pp

# All agents (including the nagios server) will use this
class nagios::export {

  nagios::resource { $::hostname:
    type => 'host',
    address => inline_template("<%= has_variable?('my_nagios_interface') ?
↪eval('ipaddress_' + my_nagios_interface) : ipaddress %>"),
    hostgroups => inline_template("<%= has_variable?('my_nagios_hostgroups') ?
↪$my_nagios_hostgroups : 'Other' %>"),
    check_command => 'check_host_alive!3000.0,80%!5000.0,100%!10',
    export => true,
  }
}

As you can see, the nagios::export class is ready to be extended with any kind of resource supported by our nagios::resource definition. Whenever we want all clients to export a particular resource, we just add it here so long as the following requirements are met:

1. The resource name must be unique.

2. The type parameter must be set.

3. The export parameter must be set to a value of true.

Now that all of our agents are exporting a nagios_host resource, we can focus on the collection side of things.

Tip: Short-and-Sweet Nagios Service Descriptions

Efficient Service Names in Nagios

When you get around to extending nagios::resource with support for the nagios_service type, you may want to consider using an inline ERB template to handle the service_description parameter. The following code removes the last word (which should be the hostname) from the description displayed in Nagios:

service_description => inline_template("<%= name.gsub(/\\w+$/,
↪'').chomp(' ') %>"),

Now, a resource defined with a unique title, such as "Puppet Agent $::hostname", is displayed as "Puppet Agent" in Nagios.