templates/agent-conf.d/jmx.yaml.erb

<%
require 'yaml'

if RUBY_VERSION < "1.9"
# Hack to avoid ruby 1.8 always reordering the hashes and
# changing this template resource at every run
# See https://github.com/DataDog/puppet-datadog-agent/issues/43
# Taken from http://www.dzone.com/snippets/generating-yaml-hashes-sorted
class Hash
  # Replacing the to_yaml function so it'll serialize hashes sorted (by their keys)
  #
  # Original function is in /usr/lib/ruby/1.8/yaml/rubytypes.rb
  def to_yaml( opts = {} )
    YAML::quick_emit( object_id, opts ) do |out|
      out.map( taguri, to_yaml_style ) do |map|
        sort.each do |k, v|   # <-- here's my addition (the 'sort')
          map.add( k, v )
        end
      end
    end
  end
end
end
%>

<%= {'init_config'=>@init_config, 'instances'=>@instances}.to_yaml %>