title: Kibana FATAL Error: [elasticsearch.url]: definition for this key is missing
body: <p>install and start was ok on a ubuntu 18.04 for kibana but I find this</p>
  
  <pre><code>FATAL  Error: [elasticsearch.url]: definition for this key is missing
  </code></pre>
  
  <p>in /var/log/kibana/kibana.stderr</p>
  
  <p>I have this</p>
  
  <pre><code>server.port: 5601
  server.host: "192.168.56.51"
  elasticsearch.url: http://localhost:9201
  </code></pre>
  
  <p>in /etc/kibana/kibana.yml
  and when I do a wget <a href="http://localhost:9201" rel="noreferrer">http://localhost:9201</a> on the machine I get the expected index.html</p>
  
  <p>any obvious reason why kibana could complain ?</p>
  
  <p>[Update]
  meantime I have reinstalled the whole installation and it works for some reason. Howerever in many forums peaple has the same issue, so there might be a pitfallduring the installation.</p>