Home / server / Questions / 34642
Accepted
sh-beta
Asked: 2009-07-02 10:30:27 +0800 CST

Call Puppet function from Puppet template?

  • 772

As of 0.24.8, can a Puppet template call a Puppet function?

I can get similar functionality by calling the function in my manifest, assigning the return value to a variable, and then using the lookupvar('variable') in the template, but I'd like to cut out the middle man.

puppet

3 Answers

  1. Best Answer

    Inside templates you have access to a scope object. All of the functions that you can access in the puppet manifests can be accessed via that scope object, although not via the same name. Prepend "function_" to the beginning of the function name. For example, here I included one template inside another: <%= scope.function_template("template2.erb") %>

    http://reductivelabs.com/trac/puppet/wiki/PuppetTemplating has great documentation about the scope object inside templates. For really deep information about template and functions you can look inside lib/puppet/parser/templatewrapper.rb and lib/puppet/parser/functions.rb.

    • 19

  2. Let me extend the question also to custom functions. Basically, you call custom functions the same way as built-in functions (using function_ prefix), but make sure you pass all params in an array:

    module Puppet::Parser::Functions
  newfunction(:namegoeshere, :type => :rvalue) do |args|
    # ...
  end
end

<%= scope.function_namegoeshere(["one","two"]) %>

    Please note it also works without the square braces on some Puppet versions. More info: https://puppet.com/docs/puppet/latest/functions_ruby_overview.html

    Another important thing is there is a bug (or feature) in Puppet 2.6 or older where custom functions are not auto-loaded into the template scope. You need to load them manually, otherwise function wont be found!

    <% Puppet::Parser::Functions::function('namegoeshere') %>

    More info: http://projects.puppetlabs.com/issues/7991

    • 3

  3. I'm not entirely sure what you mean by a Puppet function, but puppet templates are embedded Ruby, so you can do anything in the templates that you can in Ruby.

    • -2