title: AWS Glue transform a struct into dynamicframe
body: <p>I am a little new to AWSGlue. I am working on transform a raw cloudwatch json out into csv with AWSGlue. The transformation script is pretty straight forward, however documentation and example doesn't seem to be comprehensive. 
  The data structure is something like this:</p>
  
  <pre><code>{
  "Label": "RequestCount",
  "Datapoints": [
      {
          "Timestamp": "2017-07-23T00:00:00Z",
          "Sum": 41960.0,
          "Unit": "Count"
      },
      {
          "Timestamp": "2017-07-30T00:00:00Z",
          "Sum": 46065.0,
          "Unit": "Count"
      },
      {
          "Timestamp": "2017-08-24T00:00:00Z",
          "Sum": 43915.0,
          "Unit": "Count"
      },
  </code></pre>
  
  <p>The tricky part is to transform it from single dynamic frame(lable,string, datapoint array) into dynamic frames (Timestamp,string,Sum,Double,Unit,String).
  I am not sure which method to use in dynamic dataframe.</p>