private Host getHost(String clusterName, String hostName) {
    Host host = null;
    try {
      Cluster cluster = managementController.getClusters().getCluster(clusterName);
      if(cluster != null) {
        host = cluster.getHost(hostName);
      }
    } catch (Exception e) {
      LOG.warn("Exception in getting host info for jmx metrics: ", e);
    }
    return host;
  }
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