Expose monitoring.cluster_uuid in State API (#13254)

* Expose monitoring.cluster_uuid in State API

* Consume monitoring.cluster_uuid from State API in beat/stats metricset

* Consume monitoring.cluster_uuid from State API in beat/state metricset

libbeat/cmd/instance/beat.go

@@ -401,6 +401,14 @@ func (b *Beat) launch(settings Settings, bt beat.Creator) error {
 			return err
 		}
 		defer reporter.Stop()
+
+		// Expose monitoring.cluster_uuid in state API
+		if reporterSettings.ClusterUUID != "" {
+			stateRegistry := monitoring.GetNamespace("state").GetRegistry()
+			monitoringRegistry := stateRegistry.NewRegistry("monitoring")
+			clusterUUIDRegVar := monitoring.NewString(monitoringRegistry, "cluster_uuid")
+			clusterUUIDRegVar.Set(reporterSettings.ClusterUUID)
+		}
 	}
 
 	if b.Config.MetricLogging == nil || b.Config.MetricLogging.Enabled() {

metricbeat/module/beat/beat.go

@@ -93,6 +93,9 @@ type Info struct {
 
 // State construct contains the relevant data from the Beat's /state endpoint
 type State struct {
+	Monitoring struct {
+		ClusterUUID string `json:"cluster_uuid"`
+	} `json:"monitoring"`
 	Output struct {
 		Name string `json:"name"`
 	} `json:"output"`

metricbeat/module/beat/state/data_xpack.go

@@ -54,14 +54,16 @@ func eventMappingXPack(r mb.ReporterV2, m *MetricSet, info b.Info, content []byt
 		"timestamp": now,
 	}
 
-	var clusterUUID string
-	if isOutputES(state) {
-		clusterUUID = getClusterUUID(state)
-		if clusterUUID == "" {
-			// Output is ES but cluster UUID could not be determined. No point sending monitoring
-			// data with empty cluster UUID since it will not be associated with the correct ES
-			// production cluster. Log error instead.
-			return errors.Wrap(b.ErrClusterUUID, "could not determine cluster UUID")
+	clusterUUID := getMonitoringClusterUUID(state)
+	if clusterUUID == "" {
+		if isOutputES(state) {
+			clusterUUID = getClusterUUID(state)
+			if clusterUUID == "" {
+				// Output is ES but cluster UUID could not be determined. No point sending monitoring
+				// data with empty cluster UUID since it will not be associated with the correct ES
+				// production cluster. Log error instead.
+				return errors.Wrap(b.ErrClusterUUID, "could not determine cluster UUID")
+			}
 		}
 	}
 
@@ -141,3 +143,27 @@ func isOutputES(state map[string]interface{}) bool {
 
 	return name == "elasticsearch"
 }
+
+func getMonitoringClusterUUID(state map[string]interface{}) string {
+	m, exists := state["monitoring"]
+	if !exists {
+		return ""
+	}
+
+	monitoring, ok := m.(map[string]interface{})
+	if !ok {
+		return ""
+	}
+
+	c, exists := monitoring["cluster_uuid"]
+	if !exists {
+		return ""
+	}
+
+	clusterUUID, ok := c.(string)
+	if !ok {
+		return ""
+	}
+
+	return clusterUUID
+}

metricbeat/module/beat/stats/data_xpack.go

@@ -83,11 +83,16 @@ func (m *MetricSet) getClusterUUID() (string, error) {
 		return "", errors.Wrap(err, "could not get state information")
 	}
 
+	clusterUUID := state.Monitoring.ClusterUUID
+	if clusterUUID != "" {
+		return clusterUUID, nil
+	}
+
 	if state.Output.Name != "elasticsearch" {
 		return "", nil
 	}
 
-	clusterUUID := state.Outputs.Elasticsearch.ClusterUUID
+	clusterUUID = state.Outputs.Elasticsearch.ClusterUUID
 	if clusterUUID == "" {
 		// Output is ES but cluster UUID could not be determined. No point sending monitoring
 		// data with empty cluster UUID since it will not be associated with the correct ES