title: How to get number of current open shards in elsticsearch cluster?
body: <p>I can't find where to get the number of current open shards.
  I want to make monitoring to avoid cases like this:</p>
  
  <pre><code>this cluster currently has [999]/[1000] maximum shards open
  </code></pre>
  
  <p>I can get maximum limit - max_shards_per_node</p>
  
  <pre><code>$ curl -X GET "${ELK_HOST}/_cluster/settings?include_defaults=true&amp;flat_settings=true&amp;pretty" 2&gt;/dev/null | grep cluster.max_shards_per_node
  "cluster.max_shards_per_node" : "1000",
  $
  </code></pre>
  
  <p>But can't find out how to get number of the current open shards (999).</p>