title: How to pass temporary data from filter to output in logstash
body: <p>How do you pass temporary data from a filter to output in logstash?</p>
  
  <pre><code>filter {    
  
      mutate {
           add_field =&gt; {"TEMP_DATA" =&gt; "%{some value}"}
      }      
  }
  
  output {  
     elasticsearch {
         document_id =&gt; "%{TEMPDATA}"
     }
  }
  </code></pre>
  
  <p>The above will output the TEMPDATA value</p>