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vpetersson
Asked: 2013-02-08 11:40:54 +0800 CST

Best way to get list of nodes inside of Puppet template

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What is the recommended way of getting a list of all the nodes from within a Puppet template?

Let's say I have a load balancer running Nginx. Inside of the template, I want to generate a list of backend servers. For the sake of simplicity, let's say these app-servers have a hostname that matches 'appserver*'.

Currently, I define an array inside site.pp with each app-server, and use that as follows:

upstream www.foobar.com {
  <% appservers.each do |val| -%>
  server <%= val %>:80;
  <% end -%>
}

I'd like to do away with that manually defined array, and instead query Puppet.

puppet

1 Answers

  1. Best Answer

    I don't think there is one recommended way. It depends on your setup I guess.

    There are several ways to achieve this. You can use exported resources and query puppetDB.

    The method I prefer, because I'm already using Foreman, is to use foremans parser function to get the nodes list from foreman.

    So in your manifest, you can do something like:

    $appservers = foreman("hosts", 'hostgroup = appservers')

    Assuming your app-servers are in Foremans hostgroup calles 'appservers'. Here is a blog post that explains it.

    Another way, would be to store your 'appserver' list in a text file, or database, then write your own function to retrieve the list. As you can see, writing a parser function is easy.

    Another way is to use Hiera.

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