title: How to watch the logstash log?
body: <p>For my enterprise application distributed and structured logging, I use <code>logstash</code> for log aggregation and <code>elastic search</code> as log storage. I have the clear control pushing logs from my application to logstash. On the other hand, from logstash to elastic search having very thin control. </p>
  
  <p>Assume, if my <code>elasticsearch</code> goes down for some stupid reason, The logstash log(<code>/var/log/logstash/logstash.log</code>) is recording the reason clearly like the following one.</p>
  
  <pre><code>Attempted to send a bulk request to Elasticsearch configured at '["http://localhost:9200/"]', but Elasticsearch appears to be unreachable or down! {:client_config=&gt;{:hosts=&gt;["http://localhost:9200/"], :ssl=&gt;nil, :transport_options=&gt;{:socket_timeout=&gt;0, :request_timeout=&gt;0, :proxy=&gt;nil, :ssl=&gt;{}}, :transport_class=&gt;Elasticsearch::Transport::Transport::HTTP::Manticore, :logger=&gt;nil, :tracer=&gt;nil, :reload_connections=&gt;false, :retry_on_failure=&gt;false, :reload_on_failure=&gt;false, :randomize_hosts=&gt;false}, :error_message=&gt;"Connection refused", :class=&gt;"Manticore::SocketException", :level=&gt;:error}
  </code></pre>
  
  <p>How will I get noticed OR notified for the <code>error</code> level logs from logstash?</p>