Get metrics

Get metrics of components

1. get cpu-metrics of service component TASKTRACKER

   mr = mycluster.get_service("MAPREDUCE")
   mr_comp1 = mr.get_service_component('TASKTRACKER')
   metric_json = mr_comp1.get_metrics()
   print metric_json["metrics"]["cpu"]
   print"\n"

2. get cpu-metrics from a host which has component NAMENODE

   host1 = mycluster.get_host('host1')
   nn = host1.get_host_component("NAMENODE")
   metric_json = nn.get_metrics()
   print metric_json["metrics"]["cpu"]
   print"\n"