title: Elasticsearch service does not run at statup on Ubuntu 16.04
body: <p>I installed elasticsearch on Ubuntu 16.04.</p>
  
  <p>When I enter <code>sudo service elasticsearch start</code>, everything works. </p>
  
  <p>But the service is not running on startup. Before starting it manually, <code>sudo service elasticsearch status</code> gives me:</p>
  
  <pre><code>elasticsearch.service - Elasticsearch
     Loaded: loaded (/usr/lib/systemd/system/elasticsearch.service; disabled; vend
     Active: inactive (dead)
       Docs: http://www.elastic.co
  </code></pre>
  
  <p>I tried to add it to startup with:
  <code>sudo update-rc.d elasticsearch defaults</code> and <code>sudo update-rc.d elasticsearch enable</code>, but this changes nothing.</p>
  
  <p>What could be the problem, and how can I debug this?</p>