title: How to pass json/list values to a template in HEAT user_data
body: <p>need to replace user_data with dynamic values in resource group from comma_delimited_list.</p>
  <p>%index% is not working.</p>
  <pre><code>heat_template_version: 2015-10-15
  
  test_parameter:
  type: comma_delimited_list
  label: test param  list
  description: test descr
  default: 'test_param_1,test_param_2'
  .......
  ...... 
  
  type: OS::Heat::ResourceGroup
  properties:
  .........
  .........
  user_data:
      str_replace:
        template: |
          get the local value of the instance : $val
        params:
          $val: { get_param: [ test_parameter, %index% ] } 
          
          
  </code></pre>
  <p>How to pass json/list values to a template in HEAT-user_data</p>