title: Problem with dataflow job accessing external URLs
body: <p>i have a dataflow job which executes the following code</p>
  <pre><code>&gt;&gt;&gt; import urllib.request
  &gt;&gt;&gt; headers={'User-Agent': 'Mozilla/5.0 (X11; Linux x86_64) '
  ... }
  &gt;&gt;&gt; element = 'https://www.sec.gov/Archives/edgar/full-index/2019/QTR1/master.idx'
  &gt;&gt;&gt; req = urllib.request.Request(element, headers=headers)
  &gt;&gt;&gt; data = urllib.request.urlopen(req)
  &gt;&gt;&gt; data =  [line for line in data]
  &gt;&gt;&gt; data[0:2]
  [b'Description:           Master Index of EDGAR Dissemination Feed\n', b'Last Data Received:    March 31, 2019\n']
  </code></pre>
  <p>Now, exactly the same code is embedded in a dataflow job. The job is being ran using a flex template using gcloud, in the following way</p>
  <pre><code>gcloud dataflow flex-template run &quot;edgarflow23&quot; \
  --template-file-gcs-location &quot;$TEMPLATE_PATH&quot; \
  --parameters year=2020 \
  --parameters quarter=QTR1 \
  --parameters setup_file=&quot;/dataflow/template/setup.py&quot; \
  --region &quot;$REGION&quot;
  </code></pre>
  <p>And the code end up in a HTTP 403 Forbidden error
  Now when i run exactly the same code via cloud shell, i am getting exactly the same error</p>
  <ul>
  <li>When i run on my local machine, it works fine</li>
  <li>When i kick off the same dataflow job via classic template, it is working fine.</li>
  </ul>
  <p>I am puzzled to see where the problem is?
  Could anyone help?
  regards
  marco</p>