monitoring doc

Author: dai-chen

docs/sql/monitoring.md

@@ -0,0 +1,77 @@
+# Plugin Monitoring
+
+## Introduction
+
+By a stats endpoint, you are able to collect metrics for the plugin
+within the interval. Note that only node level statistics collecting is
+implemented for now. In other words, you only get the metrics for the
+node you're accessing. Cluster level statistics have yet to be
+implemented.
+
+## Node Stats
+
+### Description
+
+The meaning of fields in the response is as follows:
+
+<table>
+<colgroup>
+<col style="width: 30%" />
+<col style="width: 69%" />
+</colgroup>
+<thead>
+<tr class="header">
+<th>Field name</th>
+<th>Description</th>
+</tr>
+</thead>
+<tbody>
+<tr class="odd">
+<td><blockquote>
+<p>request_total</p>
+</blockquote></td>
+<td><blockquote>
+<p>Total count of request</p>
+</blockquote></td>
+</tr>
+<tr class="even">
+<td><blockquote>
+<p>request_count</p>
+</blockquote></td>
+<td><blockquote>
+<p>Total count of request within the interval</p>
+</blockquote></td>
+</tr>
+<tr class="odd">
+<td>failed_request_count_syserr</td>
+<td>Count of failed request due to system error within the interval</td>
+</tr>
+<tr class="even">
+<td>failed_request_count_cuserr</td>
+<td>Count of failed request due to bad request within the interval</td>
+</tr>
+<tr class="odd">
+<td><blockquote>
+<p>failed_request_count_cb</p>
+</blockquote></td>
+<td>Indicate if plugin is being circuit broken within the interval</td>
+</tr>
+</tbody>
+</table>
+
+### Example
+
+SQL query:
+
+    >> curl -H 'Content-Type: application/json' -X GET localhost:9200/_opendistro/_sql/stats
+
+Result set:
+
+    {
+      "failed_request_count_cb" : 0,
+      "failed_request_count_cuserr" : 0,
+      "circuit_breaker" : 0,
+      "request_total" : 0,
+      "request_count" : 0,
+      "failed_request_count_syserr" : 0
+    }