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require 'puppet/util'
require 'puppet/util/logging'
require 'erb'
# A template wrapper that evaluates a template in the
# context of a resource, allowing the resource attributes
# to be looked up from within the template.
# This provides functionality essentially equivalent to
# the language's template() function. You pass your file
# path and the resource you want to use into the initialization
# method, then call result() on the instance, and you get back
# a chunk of text.
# The resource's parameters are available as instance variables
# (as opposed to the language, where we use a method_missing trick).
# For example, say you have a resource that generates a file. You would
# need to implement the following style of `generate` method:
#
# def generate
# template = Puppet::Util::ResourceTemplate.new("/path/to/template", self)
#
# return Puppet::Type.type(:file).create :path => "/my/file",
# :content => template.evaluate
# end
#
# This generated file gets added to the catalog (which is what `generate` does),
# and its content is the result of the template. You need to use instance
# variables in your template, so if your template just needs to have the name
# of the generating resource, it would just have:
#
# <%= @name %>
#
# Since the ResourceTemplate class sets as instance variables all of the resource's
# parameters.
#
# Note that this example uses the generating resource as its source of
# parameters, which is generally most useful, since it allows you to configure
# the generated resource via the generating resource.
class Puppet::Util::ResourceTemplate
include Puppet::Util::Logging
def evaluate
set_resource_variables
ERB.new(File.read(@file), 0, "-").result(binding)
end
def initialize(file, resource)
raise ArgumentError, "Template %s does not exist" % file unless FileTest.exist?(file)
@file = file
@resource = resource
end
private
def set_resource_variables
@resource.to_hash.each do |param, value|
var = "@#{param.to_s}"
instance_variable_set(var, value)
end
end
end
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