func queryClusterUUID()

in internal/beater/beater.go [927:977]
43 lines of code
8 McCabe index (conditional complexity)

func queryClusterUUID(ctx context.Context, esClient *elasticsearch.Client) error {
	stateRegistry := monitoring.GetNamespace("state").GetRegistry()
	outputES := "outputs.elasticsearch"
	// Running under elastic-agent, the callback linked above is not
	// registered until later, meaning we need to check and instantiate the
	// registries if they don't exist.
	elasticsearchRegistry := stateRegistry.GetRegistry(outputES)
	if elasticsearchRegistry == nil {
		elasticsearchRegistry = stateRegistry.NewRegistry(outputES)
	}

	var (
		s  *monitoring.String
		ok bool
	)

	clusterUUID := "cluster_uuid"
	clusterUUIDRegVar := elasticsearchRegistry.Get(clusterUUID)
	if clusterUUIDRegVar != nil {
		s, ok = clusterUUIDRegVar.(*monitoring.String)
		if !ok {
			return fmt.Errorf("couldn't cast to String")
		}
	} else {
		s = monitoring.NewString(elasticsearchRegistry, clusterUUID)
	}

	var response struct {
		ClusterUUID string `json:"cluster_uuid"`
	}

	req, err := http.NewRequest("GET", "/", nil)
	if err != nil {
		return err
	}
	resp, err := esClient.Perform(req.WithContext(ctx))
	if err != nil {
		return err
	}
	defer resp.Body.Close()
	if resp.StatusCode > 299 {
		return fmt.Errorf("error querying cluster_uuid: status_code=%d", resp.StatusCode)
	}
	err = json.NewDecoder(resp.Body).Decode(&response)
	if err != nil {
		return err
	}

	s.Set(response.ClusterUUID)
	return nil
}