# Zend_Service_Amazon_Ec2: CloudWatch Monitoring

Amazon CloudWatch is an easy-to-use web service that provides comprehensive monitoring for Amazon Elastic Compute Cloud (Amazon EC2) and Elastic Load Balancing. For more details information check out the Amazon CloudWatch Developers Guide

## CloudWatch Usage

Listing Aviable Metrics

listMetrics() returns a list of up to 500 valid metrics for which there is recorded data available to a you and a NextToken string that can be used to query for the next set of results.

    $ec2_ebs = new Zend_Service_Amazon_Ec2_CloudWatch('aws_key','aws_secret_key');
    $return = $ec2_ebs->listMetrics();

Return Statistics for a given metric

getMetricStatistics() Returns data for one or more statistics of given a metric.

The maximum number of datapoints that the Amazon CloudWatch service will return in a single GetMetricStatistics request is 1,440. If a request is made that would generate more datapoints than this amount, Amazon CloudWatch will return an error. You can alter your request by narrowing the time range (StartTime, EndTime) or increasing the Period in your single request. You may also get all of the data at the granularity you originally asked for by making multiple requests with adjacent time ranges.

getMetricStatistics() only requires two parameters but it also has four additional parameters that are optional.

- Required:

- MeasureName The measure name that corresponds to the measure for the gathered metric. Valid EC2 Values are CPUUtilization, NetworkIn, NetworkOut, DiskWriteOps DiskReadBytes, DiskReadOps, DiskWriteBytes. Valid Elastic Load Balancing Metrics are Latency, RequestCount, HealthyHostCount UnHealthyHostCount. For more information click here

- Statistics The statistics to be returned for the given metric. Valid values are Average, Maximum, Minimum, Samples, Sum. You can specify this as a string or as an array of values. If you don't specify one it will default to Average instead of failing out. If you specify an incorrect option it will just skip it. For more information click here

- Optional:

- Dimensions Amazon CloudWatch allows you to specify one Dimension to further filter metric data on. If you don't specify a dimension, the service returns the aggregate of all the measures with the given measure name and time range.

- Unit The standard unit of Measurement for a given Measure. Valid Values: Seconds, Percent, Bytes, Bits, Count, Bytes/Second, Bits/Second, Count/Second, and None. Constraints: When using count/second as the unit, you should use Sum as the statistic instead of Average. Otherwise, the sample returns as equal to the number of requests instead of the number of 60-second intervals. This will cause the Average to always equals one when the unit is count/second.

- StartTime The timestamp of the first datapoint to return, inclusive. For example, 2008-02-26T19:00:00+00:00. We round your value down to the nearest minute. You can set your start time for more than two weeks in the past. However, you will only get data for the past two weeks. (in ISO 8601 format). Constraints: Must be before EndTime.

- EndTime The timestamp to use for determining the last datapoint to return. This is the last datapoint to fetch, exclusive. For example, 2008-02-26T20:00:00+00:00 (in ISO 8601 format).

    $ec2_ebs = new Zend_Service_Amazon_Ec2_CloudWatch('aws_key','aws_secret_key');
    $return = $ec2_ebs->getMetricStatistics(
                                         array('MeasureName' => 'NetworkIn',
                                               'Statistics' => array('Average')));