Monitor CPU Utilization of a Amazon EC2 instance using Amazon CloudWatch

Following code snippet show how to monitor CPU Utilization of a Amazon EC2 instance using Amazon Cloud Watch. In order to monitor the instance, Cloud Watch Monitoring should be enabled for the running instance.

private double monitorInstance(AWSCredentials credential, String instanceId) {
   try {
       AmazonCloudWatchClient cw = new AmazonCloudWatchClient(credential) ;

       long offsetInMilliseconds = 1000 * 60 * 60 * 24;
       GetMetricStatisticsRequest request = new GetMetricStatisticsRequest()
               .withStartTime(new Date(new Date().getTime() - offsetInMilliseconds))
               .withNamespace("AWS/EC2")
               .withPeriod(60 * 60)
               .withDimensions(new Dimension().withName("InstanceId").withValue(instanceId))
               .withMetricName("CPUUtilization")
               .withStatistics("Average", "Maximum")
               .withEndTime(new Date());
       GetMetricStatisticsResult getMetricStatisticsResult = cw.getMetricStatistics(request);

       double avgCPUUtilization = 0;
       List dataPoint = getMetricStatisticsResult.getDatapoints();
       for (Object aDataPoint : dataPoint) {
           Datapoint dp = (Datapoint) aDataPoint;
           avgCPUUtilization = dp.getAverage();
           log.info(instanceId + " instance's average CPU utilization : " + dp.getAverage());
       }

       return avgCPUUtilization;

   } catch (AmazonServiceException ase) {
       log.severe("Caught an AmazonServiceException, which means the request was made  "
               + "to Amazon EC2, but was rejected with an error response for some reason.");
       log.severe("Error Message:    " + ase.getMessage());
       log.severe("HTTP Status Code: " + ase.getStatusCode());
       log.severe("AWS Error Code:   " + ase.getErrorCode());
       log.severe("Error Type:       " + ase.getErrorType());
       log.severe("Request ID:       " + ase.getRequestId());

   }
   return 0;
}