title: manage.py doesn't log to stdout/stderr in Docker on Raspberry Pi
body: <p>On a Raspberry Pi 2, I used the image <code>resin/rpi-raspbian:stretch</code> for running a Django application. In my Dockerfile, I Install the <code>python3</code> package and start the application using <code>ENTRYPOINT python3 manage.py runserver 0:8000</code>. This works, BUT when my code throws error, I got NO output using <code>docker log</code> command.</p>
  <h3>Example</h3>
  <p>I have a ImportError. When I run the command manually using <code>docker exec</code>, I got the exception as expected:</p>
  <pre><code>pi@pi2:/etc/docker/container/pms $ sudo docker exec -it pms_app_1 python3 manage.py runserver 0:8000
  Unhandled exception in thread started by &lt;function check_errors.&lt;locals&gt;.wrapper at 0x75de3228&gt;
  [...]
  ImportError: No module named 'ws4redisfrontend'
  </code></pre>
  <p>But when I run the container using <code>docker-compose</code> and then open the logs, they're empty:</p>
  <pre><code>pi@pi2:/myapp $ sudo docker logs myapp_1
  pi@pi2:/myapp $ 
  </code></pre>
  <p>This behaviour is only present for the <code>manage.py</code> call. For example, when I extend the entrypoint like this:</p>
  <pre><code>ENTRYPOINT python3 -c &quot;print('printed by python inline script')&quot; &amp;&amp; python3 manage.py runserver 0:8000
  </code></pre>
  <p>I see <em>printed by python inline script</em> in the container-logs. As a newbie in Python/Django, I can't understand why this happens. But as my print example works, it seems a Django issue, and no general problem of Python. What am I missing? Debug mode is activated in <code>settings.py</code>.</p>