@Override
  public String getCollectorHostName(String clusterName, MetricsService service)
    throws SystemException {

    checkInit();
    if (service.equals(GANGLIA)) {
      return clusterGangliaCollectorMap.get(clusterName);
    } else if (service.equals(TIMELINE_METRICS)) {
      return getMetricsCollectorHostName(clusterName);
    }
    return null;
  }
Get type of Metrics system installed.
@return @MetricsService, null if none found.
ambari-server/src/main/java/org/apache/ambari/server/controller/internal/AbstractProviderModule.java