The datacat and datacat_fragment types allow you to build up a data structure which is rendered using a template. This is similar to some of the common concatenation patterns though the intent should be clearer as it pushes the boilerplate down into the type.

datacat { '/etc/nagios/objects/hostgroups.cfg':
  template => "${module_name}/hostgroups.cfg.erb",
}

datacat_fragment { "${::fqdn} in device hostgroup":
  target => '/etc/nagios/objects/hostgroups.cfg',
  data   => {
    device => [ $::fqdn ],
  },
}

# fred.dc1.notreal has an ilo fred-ilo.dc1.notreal
$ilo_fqdn = regsubst($::fqdn, '\.', '-ilo.')
datacat_fragment { "${ilo_fqdn} in device hostgroup":
  target => '/etc/nagios/objects/hostgroups.cfg',
  data   => {
    device => [ $ilo_fqdn ],
  },
}

And then in your hostgroups.cfg.erb

# hostgroups.cfg.erb
<% @data.keys.sort.each do |hostgroup| %>
define hostgroup {
    name <%= hostgroup %>
    members <%= @data[hostgroup].sort.join(',') %>
}
<% end %>

Will produce something like:

# /etc/nagios/objects/hostgroups.cfg
define hostgroup {
    name device
    members fred.dc1.notreal,fred-ilo.dc1.notreal
}

There are additional samples in a blog post I wrote to describe the approach, http://richardc.unixbeard.net/2013/02/puppet-concat-patterns/

Wraps the datacat_collector and file types to cover the most common use-case, collecting data for and templating an entire file.

The datacat_collector type deeply merges a data hash from the datacat_fragment resources that target it.

These fragments are then rendered via an erb template specified by the template_body parameter and used to update the target_field property of the related target_resource.

Sample usage:

datacat_collector { 'open_ports':
  template_body   => '<%= @data["ports"].sort.join(",") %>',
  target_resource => File_line['open_ports'],
  target_field    => 'line',
}

datacat_fragment { 'open webserver':
  target => 'open_ports',
  data   => { ports => [ 80, 443 ] },
}

datacat_fragment { 'open ssh':
  target => 'open_ports',
  data   => { ports => [ 22 ] },
}

The template is evaluated by the agent at the point of catalog evaluation, this means you cannot call out to puppet parser functions as you would when using the usual template() function.

Copyright (C) 2013 Richard Clamp

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.