[Heartbeat] Always use synthetics data streams for browser

CHANGELOG.next.asciidoc

@@ -19,6 +19,8 @@ https://github.com/elastic/beats/compare/v8.2.0\...main[Check the HEAD diff]
 - Add a new `salesforce` module to collect data from salesforce. {pull}31486[31486]
 
 *Heartbeat*
+- Browser monitors (beta) no write to the `synthetics-*` index prefix. {pull}32064[32064]
+- Setting a custom index for a given monitor is now deprecated. Streams are preferred. {pull}32064[32064]
 
 
 *Metricbeat*

heartbeat/docs/monitors/monitor-common-options.asciidoc

@@ -143,6 +143,20 @@ A list of processors to apply to the data generated by the monitor.
 See <<filtering-and-enhancing-data>> for information about specifying
 processors in your config.
 
+[float]
+[[monitor-data-stream]]
+
+Contains options pertaining to data stream naming, following the conventions followed by [Fleet Data Streams](https://www.elastic.co/guide/en/fleet/current/data-streams.html). By default Heartbeat will
+write to a datastream named `heartbeat-VERSION` except in the case of `browser` monitors, which will
+always follow the Fleet convention of `type-dataset-namespace`, where the type is always synthetics
+unless overriden.
+
+
+```yaml
+# To enable data streams with the default namespace
+data_stream.namespace: default
+```
+
 [float]
 [[monitor-pipeline]]
 ===== `pipeline`
@@ -156,8 +170,9 @@ input is used.
 
 [float]
 [[monitor-index]]
-===== `index`
+===== `index` (deprecated)
 
+This setting is now deprecated in favor of the `data_stream` option.
 If present, this formatted string overrides the index for events from this input
 (for elasticsearch outputs), or sets the `raw_index` field of the event's
 metadata (for other outputs). This string can only refer to the agent name and

heartbeat/monitors/factory.go

@@ -205,6 +205,15 @@ func preProcessors(info beat.Info, settings publishSettings, monitorType string)
 	// Always set event.dataset
 	procs.AddProcessor(actions.NewAddFields(mapstr.M{"event": mapstr.M{"dataset": dataset}}, true, true))
 
+	// always use synthetics data streams for browser monitors, there is no good reason not to
+	// the default `heartbeat` data stream won't split out network and screenshot data.
+	// at some point we should make all monitors use the `synthetics` datastreams and retire
+	// the heartbeat one, but browser is the only beta one, and it would be a breaking change
+	// to do so otherwise.
+	if monitorType == "browser" && settings.DataStream == nil {
+		settings.DataStream = &add_data_stream.DataStream{}
+	}
+
 	if settings.DataStream != nil {
 		ds := *settings.DataStream
 		if ds.Type == "" {
@@ -218,6 +227,7 @@ func preProcessors(info beat.Info, settings publishSettings, monitorType string)
 	}
 
 	if !settings.Index.IsEmpty() {
+		logp.L().Warn("Deprecated use of 'index' setting in heartbeat monitor, use 'data_stream' instead!")
 		proc, err := indexProcessor(&settings.Index, info)
 		if err != nil {
 			return nil, err

heartbeat/monitors/factory_test.go

@@ -48,19 +48,31 @@ func TestPreProcessors(t *testing.T) {
 		wantProc           bool
 		wantErr            bool
 	}{
-		"no settings should yield no processor": {
+		"no settings should yield no processor for lightweight monitor": {
 			publishSettings{},
 			"",
 			nil,
-			"browser",
+			"http",
 			false,
 			false,
 		},
+		"no settings should yield a data stream processor for browsers": {
+			publishSettings{},
+			"synthetics-browser-default",
+			&add_data_stream.DataStream{
+				Namespace: "default",
+				Dataset:   "browser",
+				Type:      "synthetics",
+			},
+			"browser",
+			true,
+			false,
+		},
 		"exact index should be used exactly": {
 			publishSettings{Index: *fmtstr.MustCompileEvent("test")},
 			"test",
 			nil,
-			"browser",
+			"http",
 			true,
 			false,
 		},