title: docker ubuntu cron -f is not working
body: <p>Trying to run a cron job in a docker container.
  HAve a supervisord properly configured<br>
  (I see <code>cron -f</code> in the <code>ps -ef</code> and if I kill it it respawns)</p>
  
  <p>crontab file (for testing):<br>
  <code>* * * * * echo hi &gt;&gt; /root/test</code></p>
  
  <p>I tried putting it in <code>/etc/cron.d/crontab</code> <code>/etc/crontab</code> and in <code>/var/spool/cron/crontabs/crontab</code></p>
  
  <p>Nothing is working - I'm not getting anything in <code>/root/test</code></p>
  
  <p>Any ideas?</p>