Allow delete and index actions with a document ID (elastic#12606)

* Add `op_type` meta key for delete and index operations with a document ID.

* Add note on why `obj` can be nil.

* Refactor and extract consts.

* Don't include metadata prefix in key.

* Stop appending `nil` else it ends up in the body.

* Error when trying to delete with no _id.

* Remove incorrect detail in comment.

* Add unit test for new op_type meta key.

* No longer required.

* Return error to caller.

* Fail event if op_type is no string.

* Use consts in error.

* Replace assert with require.

* Fail instead of panic.

* Change missed assert calls to require.

* Simplify GetMetaStringValue.

* Ignore err as key may not exist.

libbeat/beat/event.go

@@ -54,6 +54,19 @@ func (e *Event) SetID(id string) {
 	e.Meta["_id"] = id
 }
 
+func (e *Event) GetMetaStringValue(key string) (string, error) {
+	tmp, err := e.Meta.GetValue(key)
+	if err != nil {
+		return "", err
+	}
+
+	if s, ok := tmp.(string); ok {
+		return s, nil
+	}
+
+	return "", nil
+}
+
 func (e *Event) GetValue(key string) (interface{}, error) {
 	if key == "@timestamp" {
 		return e.Timestamp, nil

libbeat/esleg/eslegclient/bulkapi.go

@@ -46,6 +46,10 @@ type BulkCreateAction struct {
 	Create BulkMeta `json:"create" struct:"create"`
 }
 
+type BulkDeleteAction struct {
+	Delete BulkMeta `json:"delete" struct:"delete"`
+}
+
 type BulkMeta struct {
 	Index    string `json:"_index" struct:"_index"`
 	DocType  string `json:"_type,omitempty" struct:"_type,omitempty"`

libbeat/outputs/elasticsearch/client.go

@@ -67,8 +67,16 @@ type bulkResultStats struct {
 
 const (
 	defaultEventType = "doc"
+	opTypeCreate     = "create"
+	opTypeDelete     = "delete"
+	opTypeIndex      = "index"
 )
 
+// opTypeKey defines the metadata key name for event operation type.
+// The key's value can be an empty string, `create`, `index`, or `delete`. If empty, it will assume
+// either `create` or `index`. See `createEventBulkMeta`. If in doubt, set explicitly.
+const opTypeKey = "op_type"
+
 // NewClient instantiates a new client.
 func NewClient(
 	s ClientSettings,
@@ -281,7 +289,12 @@ func bulkEncodePublishRequest(
 			log.Errorf("Failed to encode event meta data: %+v", err)
 			continue
 		}
-		bulkItems = append(bulkItems, meta, event)
+		if opType, err := event.GetMetaStringValue(opTypeKey); err == nil && opType == opTypeDelete {
+			// We don't include the event source in a bulk DELETE
+			bulkItems = append(bulkItems, meta)
+		} else {
+			bulkItems = append(bulkItems, meta, event)
+		}
 		okEvents = append(okEvents, data[i])
 	}
 	return okEvents, bulkItems
@@ -311,16 +324,8 @@ func createEventBulkMeta(
 		return nil, err
 	}
 
-	var id string
-	if m := event.Meta; m != nil {
-		if tmp := m["_id"]; tmp != nil {
-			if s, ok := tmp.(string); ok {
-				id = s
-			} else {
-				log.Errorf("Event ID '%v' is no string value", id)
-			}
-		}
-	}
+	id, _ := event.GetMetaStringValue("_id")
+	opType, _ := event.GetMetaStringValue(opTypeKey)
 
 	meta := eslegclient.BulkMeta{
 		Index:    index,
@@ -329,7 +334,17 @@ func createEventBulkMeta(
 		ID:       id,
 	}
 
+	if opType == opTypeDelete {
+		if id != "" {
+			return eslegclient.BulkDeleteAction{Delete: meta}, nil
+		} else {
+			return nil, fmt.Errorf("%s %s requires _id", opTypeKey, opTypeDelete)
+		}
+	}
 	if id != "" || version.Major > 7 || (version.Major == 7 && version.Minor >= 5) {
+		if opType == opTypeIndex {
+			return eslegclient.BulkIndexAction{Index: meta}, nil
+		}
 		return eslegclient.BulkCreateAction{Create: meta}, nil
 	}
 	return eslegclient.BulkIndexAction{Index: meta}, nil

libbeat/outputs/elasticsearch/client_test.go

@@ -319,6 +319,68 @@ func TestBulkEncodeEvents(t *testing.T) {
 	}
 }
 
+func TestBulkEncodeEventsWithOpType(t *testing.T) {
+	cases := []common.MapStr{
+		{"_id": "111", "op_type": "index", "message": "test 1", "bulkIndex": 0},
+		{"_id": "112", "op_type": "", "message": "test 2", "bulkIndex": 2},
+		{"_id": "", "op_type": "delete", "message": "test 6", "bulkIndex": -1}, // this won't get encoded due to missing _id
+		{"_id": "", "op_type": "", "message": "test 3", "bulkIndex": 4},
+		{"_id": "114", "op_type": "delete", "message": "test 4", "bulkIndex": 6},
+		{"_id": "115", "op_type": "index", "message": "test 5", "bulkIndex": 7},
+	}
+
+	cfg := common.MustNewConfigFrom(common.MapStr{})
+	info := beat.Info{
+		IndexPrefix: "test",
+		Version:     version.GetDefaultVersion(),
+	}
+
+	im, err := idxmgmt.DefaultSupport(nil, info, common.NewConfig())
+	require.NoError(t, err)
+
+	index, pipeline, err := buildSelectors(im, info, cfg)
+	require.NoError(t, err)
+
+	events := make([]publisher.Event, len(cases))
+	for i, fields := range cases {
+		events[i] = publisher.Event{
+			Content: beat.Event{
+				Meta: common.MapStr{
+					"_id":     fields["_id"],
+					"op_type": fields["op_type"],
+				},
+				Fields: common.MapStr{
+					"message": fields["message"],
+				},
+			}}
+	}
+
+	encoded, bulkItems := bulkEncodePublishRequest(logp.L(), *common.MustNewVersion(version.GetDefaultVersion()), index, pipeline, events)
+	require.Equal(t, len(events)-1, len(encoded), "all events should have been encoded")
+	require.Equal(t, 9, len(bulkItems), "incomplete bulk")
+
+	for i := 0; i < len(cases); i++ {
+		bulkEventIndex, _ := cases[i]["bulkIndex"].(int)
+		if bulkEventIndex == -1 {
+			continue
+		}
+		caseOpType, _ := cases[i]["op_type"].(string)
+		caseMessage, _ := cases[i]["message"].(string)
+		switch bulkItems[bulkEventIndex].(type) {
+		case eslegclient.BulkCreateAction:
+			validOpTypes := []string{opTypeCreate, ""}
+			require.Contains(t, validOpTypes, caseOpType, caseMessage)
+		case eslegclient.BulkIndexAction:
+			require.Equal(t, opTypeIndex, caseOpType, caseMessage)
+		case eslegclient.BulkDeleteAction:
+			require.Equal(t, opTypeDelete, caseOpType, caseMessage)
+		default:
+			require.FailNow(t, "unknown type")
+		}
+	}
+
+}
+
 func TestClientWithAPIKey(t *testing.T) {
 	var headers http.Header