title: Specifying machine type for a GCP Dataflow job in Python
body: <p>I have a Dataflow template generated by Dataprep and am executing it using Composer (ie Apache Airflow).</p>
  
  <p>The task is triggering the Dataflow job, but this is then failing with an error which <a href="https://stackoverflow.com/questions/36309770/diagnosing-failed-cloud-dataflow-pipeline">according to posts on SO</a> indicates that I need to specify a machine type with higher memory.</p>
  
  <p>I'm specifying <code>machineType</code> in the <code>DataflowTemplateOperator</code>, but it's not applying to the Dataflow job:</p>
  
  <pre><code>dataflow_default_options={
      'project': 'projectname',
      'zone': 'europe-west1-b',
      'tempLocation': 'gs://bucketname-dataprep-working/temp/',
      'machineType': 'n1-highmem-4'
  },
  </code></pre>
  
  <p>Having investigated this for some time, I've seen conflicting advice as to what to call the <code>machineType</code> attribute - I've also tried <code>workerMachineType</code>, <code>machine-type</code> and <code>worker-machine-type</code> to no avail.</p>
  
  <p>Has anyone here successfully specified a worker type for <code>DataflowTemplateOperator</code>?</p>