Omit 'fields' from Filebeat events when null

CHANGELOG.asciidoc

@@ -45,6 +45,7 @@ https://github.com/elastic/beats/compare/v1.1.0...master[Check the HEAD diff]
 *Filebeat*
 - Stop filebeat if filebeat is started without any prospectors defined or empty prospectors {pull}644[644] {pull}647[647]
 - Improve shutdown of crawler and prospector to wait for clean completion {pull}720[720]
+- Omit `fields` from Filebeat events when null {issue}899[899]
 
 *Winlogbeat*
 

filebeat/harvester/log.go

@@ -170,7 +170,7 @@ func (h *Harvester) Harvest() {
 				Offset:       h.Offset,
 				Bytes:        bytesRead,
 				Text:         &text,
-				Fields:       &h.Config.Fields,
+				Fields:       h.Config.Fields,
 				Fileinfo:     &info,
 			}
 

filebeat/input/file.go

@@ -24,7 +24,7 @@ type FileEvent struct {
 	Offset       int64
 	Bytes        int
 	Text         *string
-	Fields       *common.MapStr
+	Fields       common.MapStr
 	Fileinfo     *os.FileInfo
 
 	fieldsUnderRoot bool
@@ -77,7 +77,7 @@ func (f *FileEvent) ToMapStr() common.MapStr {
 
 	if f.Fields != nil {
 		if f.fieldsUnderRoot {
-			for key, value := range *f.Fields {
+			for key, value := range f.Fields {
 				// in case of conflicts, overwrite
 				_, found := event[key]
 				if found {

filebeat/input/file_test.go

@@ -115,7 +115,7 @@ func TestFileEventToMapStr(t *testing.T) {
 
 func TestFieldsUnderRoot(t *testing.T) {
 	event := FileEvent{
-		Fields: &common.MapStr{
+		Fields: common.MapStr{
 			"hello": "world",
 		},
 	}

filebeat/tests/system/test_fields.py

@@ -80,3 +80,4 @@ def test_beat_fields(self):
         doc = output[0]
         assert doc["beat.name"] == "testShipperName"
         assert doc["beat.hostname"] == socket.gethostname()
+        assert "fields" not in doc