keep track of elastic search version and generate query according to version

public/app/plugins/datasource/elasticsearch/datasource.js

@@ -23,9 +23,11 @@ function (angular, _, moment, kbn, ElasticQueryBuilder, IndexPattern, ElasticRes
       this.name = datasource.name;
       this.index = datasource.index;
       this.timeField = datasource.jsonData.timeField;
+      this.elasticsearchVersion = datasource.jsonData.elasticsearchVersion;
       this.indexPattern = new IndexPattern(datasource.index, datasource.jsonData.interval);
       this.queryBuilder = new ElasticQueryBuilder({
-        timeField: this.timeField
+        timeField: this.timeField,
+        elasticsearchVersion: this.elasticsearchVersion
       });
     }
 

public/app/plugins/datasource/elasticsearch/partials/config.html

@@ -20,7 +20,7 @@
 	</ul>
 	<div class="clearfix"></div>
 </div>
-<div class="tight-form last">
+<div class="tight-form">
 	<ul class="tight-form-list">
 		<li class="tight-form-item" style="width: 144px">
 			Time field name
@@ -31,3 +31,14 @@
 	</ul>
 	<div class="clearfix"></div>
 </div>
+<div class="tight-form last">
+	<ul class="tight-form-list">
+		<li class="tight-form-item" style="width: 144px">
+			Elasticsearch version
+		</li>
+		<li>
+			<select class="input-medium tight-form-input" ng-model="current.jsonData.elasticsearchVersion" ng-options="f.value as f.name for f in elasticsearchVersions"></select>
+		</li>
+	</ul>
+	<div class="clearfix"></div>
+</div>

public/app/plugins/datasource/elasticsearch/query_builder.js

@@ -6,11 +6,18 @@ function (angular) {
 
   function ElasticQueryBuilder(options) {
     this.timeField = options.timeField;
+    this.elasticsearchVersion = options.elasticsearchVersion;
   }
 
   ElasticQueryBuilder.prototype.getRangeFilter = function() {
     var filter = {};
     filter[this.timeField] = {"gte": "$timeFrom", "lte": "$timeTo"};
+
+    // elastic search versions above 2.0 require the time format to be specified
+    if (this.elasticsearchVersion >= 2) {
+      filter[this.timeField]["format"] = "epoch_millis";
+    }
+
     return filter;
   };
 
@@ -129,6 +136,10 @@ function (angular) {
             "min_doc_count": 0,
             "extended_bounds": { "min": "$timeFrom", "max": "$timeTo" }
           };
+          // elastic search versions above 2.0 require the time format to be specified
+          if (this.elasticsearchVersion >= 2) {
+            esAgg["date_histogram"]["format"] = "epoch_millis";
+          }
           break;
         }
         case 'filters': {