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Amazon CloudWatch
User Guide

Publish Custom Metrics

You can publish your own metrics to CloudWatch using the AWS CLI or an API. You can view statistical graphs of your published metrics with the AWS Management Console.

CloudWatch stores data about a metric as a series of data points. Each data point has an associated time stamp. You can even publish an aggregated set of data points called a statistic set.

Using Dimensions

When publishing custom metrics, you will often use the --dimensions parameter. A dimension further clarifies what the metric is, and what data it stores. You can have up to 10 dimensions in one metric, and each dimension is defined by a Name and Value pair.

Note that how you specify a dimension is different when you use different commands. With put-metric-data, you specify each dimension as MyName=MyValue, while with get-metric-statistics or put-metric-alarm you use the format Name=MyName, Value=MyValue. For example, the following command publishes a "Buffers" metric with two dimensions named InstanceId and InstanceType.

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aws cloudwatch put-metric-data --metric-name Buffers --namespace MyNameSpace --unit Bytes --value 231434333 --dimensions InstanceId=1-23456789,InstanceType=m1.small

And then this command retrieves statistics for that same metric. Note that you separate the Name and Value parts of a single dimension with commas, but you use a space between one dimension and the next if you have multiple dimensions.

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aws cloudwatch get-metric-statistics --metric-name Buffers --namespace MyNameSpace --dimensions Name=InstanceId,Value=1-23456789 Name=InstanceType,Value=m1.small --start-time 2016-10-15T04:00:00Z --end-time 2016-10-19T07:00:00Z --statistics Average --period 60

Also note that if a single metric includes multiple dimensions, you must specify a value for every defined dimension when you use get-metric-statistics. For example, the Amazon S3 metric BucketSizeBytes includes the dimensions BucketName and StorageType, so you must specify both dimensions with get-metric-statistics.

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aws cloudwatch get-metric-statistics --metric-name BucketSizeBytes --start-time 2017-01-23T14:23:00Z --end-time 2017-01-26T19:30:00Z --period 3600 --namespace AWS/S3 --statistics Maximum --dimensions Name=BucketName,Value=MyBucketName Name=StorageType,Value=StandardStorage --output table

You can see what dimensions are defined for a metric by using the list-metrics command.

Publish Single Data Points

To publish a single data point for a new or existing metric, use the put-metric-data command with one value and time stamp. For example, the following actions each publish one data point:

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aws cloudwatch put-metric-data --metric-name PageViewCount --namespace MyService --value 2 --timestamp 2016-10-14T12:00:00.000Z aws cloudwatch put-metric-data --metric-name PageViewCount --namespace MyService --value 4 --timestamp 2016-10-14T12:00:01.000Z aws cloudwatch put-metric-data --metric-name PageViewCount --namespace MyService --value 5 --timestamp 2016-10-14T12:00:02.000Z

If you call this command with a new metric name, CloudWatch creates a metric for you. Otherwise, CloudWatch associates your data with the existing metric that you specified.

Note

When you create a metric, it can take up to two minutes before you can retrieve statistics for the new metric using the get-metric-statistics command. However, it can take up to fifteen minutes before the new metric appears in the list of metrics retrieved using the list-metrics command.

Although you can publish data points with time stamps as granular as one-thousandth of a second, CloudWatch aggregates the data to a minimum granularity of one minute. CloudWatch records the average (sum of all items divided by number of items) of the values received for every 1-minute period, as well as number of samples, maximum value, and minimum value for the same time period. For example, the PageViewCount metric from the previous examples contains three data points with time stamps just seconds apart. CloudWatch aggregates the three data points because they all have time stamps within a one-minute period.

CloudWatch uses one-minute boundaries when aggregating data points. For example, CloudWatch aggregates the data points from the previous example because all three data points fall within the one-minute period that begins at 2016-10-20T12:00:00.000Z and ends at 2016-10-20T12:01:00.000Z.

You can use the get-metric-statistics command to retrieve statistics based on the data points that you published.

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aws cloudwatch get-metric-statistics --namespace MyService --metric-name PageViewCount \ --statistics "Sum" "Maximum" "Minimum" "Average" "SampleCount" \ --start-time 2016-10-20T12:00:00.000Z --end-time 2016-10-20T12:05:00.000Z --period 60

The following is example output:

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{ "Datapoints": [ { "SampleCount": 3.0, "Timestamp": "2016-10-20T12:00:00Z", "Average": 3.6666666666666665, "Maximum": 5.0, "Minimum": 2.0, "Sum": 11.0, "Unit": "None" } ], "Label": "PageViewCount" }

Publish Statistic Sets

You can aggregate your data before you publish to CloudWatch. When you have multiple data points per minute, aggregating data minimizes the number of calls to put-metric-data. For example, instead of calling put-metric-data multiple times for three data points that are within three seconds of each other, you can aggregate the data into a statistic set that you publish with one call:

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aws cloudwatch put-metric-data --metric-name PageViewCount --namespace MyService --statistic-value Sum=11,Minimum=2,Maximum=5,SampleCount=3 --timestamp 2016-10-14T12:00:00.000Z

Publish the Value Zero

When your data is more sporadic and you have periods that have no associated data, you can choose to publish the value zero (0) for that period or no value at all. You might want to publish zero instead of no value if you use periodic calls to PutMetricData to monitor the health of your application. For example, you can set a CloudWatch alarm to notify you if your application fails to publish metrics every five minutes. You want such an application to publish zeros for periods with no associated data.

You might also publish zeros if you want to track the total number of data points or if you want statistics such as minimum and average to include data points with the value 0.