support date pattern in AWS Elasticsearch index name

Author: megastef

lib/plugins/output/aws-elasticsearch.js

@@ -43,8 +43,23 @@ function OutputAwsElasticsearch (config, eventEmitter) {
 }
 
 OutputAwsElasticsearch.prototype.eventHandler = function (data, context) {
+  // support for time-based index patterns
+  var index = this.config.index
+  index = index.replace(/YYYY|MM|DD/g, function (match) {
+    if (match === 'YYYY') {
+      return '' + data['@timestamp'].getFullYear()
+    }
+    if (match === 'MM') {
+      return ('0' + (data['@timestamp'].getMonth() + 1)).substr(-2)
+    }
+    if (match === 'DD') {
+      return ('0' + data['@timestamp'].getDate()).substr(-2)
+    }
+    return match
+  })
+
   var obj = {
-    index: this.config.index,
+    index: index,
     type: this.config.type,
     body: data
   }