Which Amazon Web Services AWS service feature monitors a metric and sends an alert when the metric changes?

Amazon CloudWatch is basically a metrics repository. An AWS service—such as Amazon EC2—puts metrics into the repository, and you retrieve statistics based on those metrics. If you put your own custom metrics into the repository, you can retrieve statistics on these metrics as well.

Table of Contents Show

Instance metrics
Dedicated Host metrics
Amazon EBS metrics for Nitro-based instances
Status check metrics
Traffic mirroring metrics
Auto Scaling group metrics
Amazon EC2 metric dimensions
Amazon EC2 usage metrics
List metrics using the console
List metrics using the AWS CLI

You can use metrics to calculate statistics and then present the data graphically in the CloudWatch console. For more information about the other AWS resources that generate and send metrics to CloudWatch, see AWS services that publish CloudWatch metrics.

You can configure alarm actions to stop, start, or terminate an Amazon EC2 instance when certain criteria are met. In addition, you can create alarms that initiate Amazon EC2 Auto Scaling and Amazon Simple Notification Service (Amazon SNS) actions on your behalf. For more information about creating CloudWatch alarms, see Alarms.

AWS Cloud computing resources are housed in highly available data center facilities. To provide additional scalability and reliability, each data center facility is located in a specific geographical area, known as a Region. Each Region is designed to be completely isolated from the other Regions, to achieve the greatest possible failure isolation and stability. Metrics are stored separately in Regions, but you can use CloudWatch cross-Region functionality to aggregate statistics from different Regions. For more information, see Cross-account cross-Region CloudWatch console and Regions and Endpoints in the Amazon Web Services General Reference.

You can monitor your instances using Amazon CloudWatch, which collects and processes raw data from Amazon EC2 into readable, near real-time metrics. These statistics are recorded for a period of 15 months, so that you can access historical information and gain a better perspective on how your web application or service is performing.

By default, Amazon EC2 sends metric data to CloudWatch in 5-minute periods. To send metric data for your instance to CloudWatch in 1-minute periods, you can enable detailed monitoring on the instance. For more information, see Enable or turn off detailed monitoring for your instances.

The Amazon EC2 console displays a series of graphs based on the raw data from Amazon CloudWatch. Depending on your needs, you might prefer to get data for your instances from Amazon CloudWatch instead of the graphs in the console.

For more information about Amazon CloudWatch, see the Amazon CloudWatch User Guide.

Metrics are data about the performance of your systems. By default, many services provide free metrics for resources (such as Amazon EC2 instances, Amazon EBS volumes, and Amazon RDS DB instances). You can also enable detailed monitoring for some resources, such as your Amazon EC2 instances, or publish your own application metrics. Amazon CloudWatch can load all the metrics in your account (both AWS resource metrics and application metrics that you provide) for search, graphing, and alarms.

Metric data is kept for 15 months, enabling you to view both up-to-the-minute data and historical data.

To graph metrics in the console, you can use CloudWatch Metrics Insights, a high-performance SQL query engine that you can use to identify trends and patterns within all your metrics in real time.

Amazon EC2 sends metrics to Amazon CloudWatch. You can use the AWS Management Console, the AWS CLI, or an API to list the metrics that Amazon EC2 sends to CloudWatch. By default, each data point covers the 5 minutes that follow the start time of activity for the instance. If you've enabled detailed monitoring, each data point covers the next minute of activity from the start time. Note that for the Minimum, Maximum, and Average statistics, the minimum granularity for the metrics that EC2 provides is 1 minute.

For information about getting the statistics for these metrics, see Get statistics for metrics for your instances.

Instance metrics

The AWS/EC2 namespace includes the following instance metrics.

Metric	Description
CPUUtilization	The percentage of allocated EC2 compute units that are currently in use on the instance. This metric identifies the processing power required to run an application on a selected instance. Depending on the instance type, tools in your operating system can show a different percentage than CloudWatch when the instance is not allocated a full processor core. Units: Percent
DiskReadOps	Completed read operations from all instance store volumes available to the instance in a specified period of time. To calculate the average I/O operations per second (IOPS) for the period, divide the total operations in the period by the number of seconds in that period. If there are no instance store volumes, either the value is 0 or the metric is not reported. Units: Count
DiskWriteOps	Completed write operations to all instance store volumes available to the instance in a specified period of time. To calculate the average I/O operations per second (IOPS) for the period, divide the total operations in the period by the number of seconds in that period. If there are no instance store volumes, either the value is 0 or the metric is not reported. Units: Count
DiskReadBytes	Bytes read from all instance store volumes available to the instance. This metric is used to determine the volume of the data the application reads from the hard disk of the instance. This can be used to determine the speed of the application. The number reported is the number of bytes received during the period. If you are using basic (5-minute) monitoring, you can divide this number by 300 to find Bytes/second. If you have detailed (1-minute) monitoring, divide it by 60. If there are no instance store volumes, either the value is 0 or the metric is not reported. Units: Bytes
DiskWriteBytes	Bytes written to all instance store volumes available to the instance. This metric is used to determine the volume of the data the application writes onto the hard disk of the instance. This can be used to determine the speed of the application. The number reported is the number of bytes received during the period. If you are using basic (5-minute) monitoring, you can divide this number by 300 to find Bytes/second. If you have detailed (1-minute) monitoring, divide it by 60. If there are no instance store volumes, either the value is 0 or the metric is not reported. Units: Bytes
MetadataNoToken	The number of times the instance metadata service was successfully accessed using a method that does not use a token. This metric is used to determine if there are any processes accessing instance metadata that are using Instance Metadata Service Version 1, which does not use a token. If all requests use token-backed sessions, i.e., Instance Metadata Service Version 2, the value is 0. For more information, see Transition to using Instance Metadata Service Version 2. Units: Count
NetworkIn	The number of bytes received by the instance on all network interfaces. This metric identifies the volume of incoming network traffic to a single instance. The number reported is the number of bytes received during the period. If you are using basic (5-minute) monitoring and the statistic is Sum, you can divide this number by 300 to find Bytes/second. If you have detailed (1-minute) monitoring and the statistic is Sum, divide it by 60. Units: Bytes
NetworkOut	The number of bytes sent out by the instance on all network interfaces. This metric identifies the volume of outgoing network traffic from a single instance. The number reported is the number of bytes sent during the period. If you are using basic (5-minute) monitoring and the statistic is Sum, you can divide this number by 300 to find Bytes/second. If you have detailed (1-minute) monitoring and the statistic is Sum, divide it by 60. Units: Bytes
NetworkPacketsIn	The number of packets received by the instance on all network interfaces. This metric identifies the volume of incoming traffic in terms of the number of packets on a single instance. This metric is available for basic monitoring only (5-minute periods). To calculate the number of packets per second (PPS) your instance received for the 5 minutes, divide the Sum statistic value by 300. Units: Count
NetworkPacketsOut	The number of packets sent out by the instance on all network interfaces. This metric identifies the volume of outgoing traffic in terms of the number of packets on a single instance. This metric is available for basic monitoring only (5-minute periods). To calculate the number of packets per second (PPS) your instance sent for the 5 minutes, divide the Sum statistic value by 300. Units: Count

The AWS/EC2 namespace includes the following CPU credit metrics for your burstable performance instances.

Metric	Description
CPUCreditUsage	The number of CPU credits spent by the instance for CPU utilization. One CPU credit equals one vCPU running at 100% utilization for one minute or an equivalent combination of vCPUs, utilization, and time (for example, one vCPU running at 50% utilization for two minutes or two vCPUs running at 25% utilization for two minutes). CPU credit metrics are available at a 5-minute frequency only. If you specify a period greater than five minutes, use the Sum statistic instead of the Average statistic. Units: Credits (vCPU-minutes)
CPUCreditBalance	The number of earned CPU credits that an instance has accrued since it was launched or started. For T2 Standard, the CPUCreditBalance also includes the number of launch credits that have been accrued. Credits are accrued in the credit balance after they are earned, and removed from the credit balance when they are spent. The credit balance has a maximum limit, determined by the instance size. After the limit is reached, any new credits that are earned are discarded. For T2 Standard, launch credits do not count towards the limit. The credits in the CPUCreditBalance are available for the instance to spend to burst beyond its baseline CPU utilization. When an instance is running, credits in the CPUCreditBalance do not expire. When a T3 or T3a instance stops, the CPUCreditBalance value persists for seven days. Thereafter, all accrued credits are lost. When a T2 instance stops, the CPUCreditBalance value does not persist, and all accrued credits are lost. CPU credit metrics are available at a 5-minute frequency only. Units: Credits (vCPU-minutes)
CPUSurplusCreditBalance	The number of surplus credits that have been spent by an unlimited instance when its CPUCreditBalance value is zero. The CPUSurplusCreditBalance value is paid down by earned CPU credits. If the number of surplus credits exceeds the maximum number of credits that the instance can earn in a 24-hour period, the spent surplus credits above the maximum incur an additional charge. CPU credit metrics are available at a 5-minute frequency only. Units: Credits (vCPU-minutes)
CPUSurplusCreditsCharged	The number of spent surplus credits that are not paid down by earned CPU credits, and which thus incur an additional charge. Spent surplus credits are charged when any of the following occurs: The spent surplus credits exceed the maximum number of credits that the instance can earn in a 24-hour period. Spent surplus credits above the maximum are charged at the end of the hour. The instance is stopped or terminated. The instance is switched from unlimited to standard. CPU credit metrics are available at a 5-minute frequency only. Units: Credits (vCPU-minutes)

Dedicated Host metrics

The AWS/EC2 namespace includes the following metrics for T3 Dedicated Hosts.

Metric

Description

DedicatedHostCPUUtilization

The percentage of allocated compute capacity that is currently in use by the instances running on the Dedicated Host.

Unit: Percent

Amazon EBS metrics for Nitro-based instances

The AWS/EC2 namespace includes the following Amazon EBS metrics for the Nitro-based instances. For the list of Nitro-based instance types, see Instances built on the Nitro System.

Metric	Description
EBSReadOps	Completed read operations from all Amazon EBS volumes attached to the instance in a specified period of time. To calculate the average read I/O operations per second (Read IOPS) for the period, divide the total operations in the period by the number of seconds in that period. If you are using basic (5-minute) monitoring, you can divide this number by 300 to calculate the Read IOPS. If you have detailed (1-minute) monitoring, divide it by 60. Unit: Count
EBSWriteOps	Completed write operations to all EBS volumes attached to the instance in a specified period of time. To calculate the average write I/O operations per second (Write IOPS) for the period, divide the total operations in the period by the number of seconds in that period. If you are using basic (5-minute) monitoring, you can divide this number by 300 to calculate the Write IOPS. If you have detailed (1-minute) monitoring, divide it by 60. Unit: Count
EBSReadBytes	Bytes read from all EBS volumes attached to the instance in a specified period of time. The number reported is the number of bytes read during the period. If you are using basic (5-minute) monitoring, you can divide this number by 300 to find Read Bytes/second. If you have detailed (1-minute) monitoring, divide it by 60. Unit: Bytes
EBSWriteBytes	Bytes written to all EBS volumes attached to the instance in a specified period of time. The number reported is the number of bytes written during the period. If you are using basic (5-minute) monitoring, you can divide this number by 300 to find Write Bytes/second. If you have detailed (1-minute) monitoring, divide it by 60. Unit: Bytes
EBSIOBalance%	Provides information about the percentage of I/O credits remaining in the burst bucket. This metric is available for basic monitoring only. This metric is available only for some .4xlarge instance sizes and smaller that burst to their maximum performance for only 30 minutes at least once every 24 hours. For a complete list of instance sizes that support this metric, see the instances types indicated with an asterisk () in the Instance size column in the EBS optimized by default table. The Sum statistic is not applicable to this metric. Unit: Percent
EBSByteBalance%	Provides information about the percentage of throughput credits remaining in the burst bucket. This metric is available for basic monitoring only. This metric is available only for some .4xlarge instance sizes and smaller that burst to their maximum performance for only 30 minutes at least once every 24 hours. For a complete list of instance sizes that support this metric, see the instances types indicated with an asterisk () in the Instance size column in the EBS optimized by default table. The Sum statistic is not applicable to this metric. Unit: Percent

For information about the metrics provided for your EBS volumes, see Amazon EBS metrics. For information about the metrics provided for your Spot fleets, see CloudWatch metrics for Spot Fleet.

Status check metrics

The AWS/EC2 namespace includes the following status check metrics. By default, status check metrics are available at a 1-minute frequency at no charge. For a newly-launched instance, status check metric data is only available after the instance has completed the initialization state (within a few minutes of the instance entering the running state). For more information about EC2 status checks, see Status checks for your instances.

Metric

Description

StatusCheckFailed

Reports whether the instance has passed both the instance status check and the system status check in the last minute.

This metric can be either 0 (passed) or 1 (failed).

By default, this metric is available at a 1-minute frequency at no charge.

Units: Count

StatusCheckFailed_Instance

Reports whether the instance has passed the instance status check in the last minute.

This metric can be either 0 (passed) or 1 (failed).

By default, this metric is available at a 1-minute frequency at no charge.

Units: Count

StatusCheckFailed_System

Reports whether the instance has passed the system status check in the last minute.

This metric can be either 0 (passed) or 1 (failed).

By default, this metric is available at a 1-minute frequency at no charge.

Units: Count

Traffic mirroring metrics

The AWS/EC2 namespace includes metrics for mirrored traffic. For more information, see Monitor mirrored traffic using Amazon CloudWatch in the Amazon VPC Traffic Mirroring Guide.

Auto Scaling group metrics

The AWS/AutoScaling namespace includes metrics for Auto Scaling groups. For more information, see Monitor CloudWatch metrics for your Auto Scaling groups and instances in the Amazon EC2 Auto Scaling User Guide.

Amazon EC2 metric dimensions

You can use the following dimensions to refine the metrics listed in the previous tables.

Dimension	Description
AutoScalingGroupName	This dimension filters the data you request for all instances in a specified capacity group. An Auto Scaling group is a collection of instances you define if you're using Auto Scaling. This dimension is available only for Amazon EC2 metrics when the instances are in such an Auto Scaling group. Available for instances with Detailed or Basic Monitoring enabled.
ImageId	This dimension filters the data you request for all instances running this Amazon EC2 Amazon Machine Image (AMI). Available for instances with Detailed Monitoring enabled.
InstanceId	This dimension filters the data you request for the identified instance only. This helps you pinpoint an exact instance from which to monitor data.
InstanceType	This dimension filters the data you request for all instances running with this specified instance type. This helps you categorize your data by the type of instance running. For example, you might compare data from an m1.small instance and an m1.large instance to determine which has the better business value for your application. Available for instances with Detailed Monitoring enabled.

Amazon EC2 usage metrics

You can use CloudWatch usage metrics to provide visibility into your account's usage of resources. Use these metrics to visualize your current service usage on CloudWatch graphs and dashboards.

Amazon EC2 usage metrics correspond to AWS service quotas. You can configure alarms that alert you when your usage approaches a service quota. For more information about CloudWatch integration with service quotas, see AWS usage metrics in the Amazon CloudWatch User Guide.

Amazon EC2 publishes the following metrics in the AWS/Usage namespace.

Metric

Description

ResourceCount

The number of the specified resources running in your account. The resources are defined by the dimensions associated with the metric.

The most useful statistic for this metric is MAXIMUM, which represents the maximum number of resources used during the 1-minute period.

The following dimensions are used to refine the usage metrics that are published by Amazon EC2.

Dimension	Description
Service	The name of the AWS service containing the resource. For Amazon EC2 usage metrics, the value for this dimension is EC2.
Type	The type of entity that is being reported. Currently, the only valid value for Amazon EC2 usage metrics is Resource.
Resource	The type of resource that is running. Currently, the only valid value for Amazon EC2 usage metrics is vCPU, which returns information on instances that are running.
Class	The class of resource being tracked. For Amazon EC2 usage metrics with vCPU as the value of the Resource dimension, the valid values are Standard/OnDemand, F/OnDemand, G/OnDemand, Inf/OnDemand, P/OnDemand, and X/OnDemand. The values for this dimension define the first letter of the instance types that are reported by the metric. For example, Standard/OnDemand returns information about all running instances with types that start with A, C, D, H, I, M, R, T, and Z, and G/OnDemand returns information about all running instances with types that start with G.

List metrics using the console

Metrics are grouped first by namespace, and then by the various dimension combinations within each namespace. For example, you can view all metrics provided by Amazon EC2, or metrics grouped by instance ID, instance type, image (AMI) ID, or Auto Scaling group.

To view available metrics by category (console)

Open the CloudWatch console at https://console.aws.amazon.com/cloudwatch/.
In the navigation pane, choose Metrics.
Choose the EC2 metric namespace.
Select a metric dimension (for example, Per-Instance Metrics).
To sort the metrics, use the column heading. To graph a metric, select the check box next to the metric. To filter by resource, choose the resource ID and then choose Add to search. To filter by metric, choose the metric name and then choose Add to search.

List metrics using the AWS CLI

Use the list-metrics command to list the CloudWatch metrics for your instances.

To list all the available metrics for Amazon EC2 (AWS CLI)

The following example specifies the AWS/EC2 namespace to view all the metrics for Amazon EC2.

aws cloudwatch list-metrics --namespace AWS/EC2

The following is example output:

{ "Metrics": [ { "Namespace": "AWS/EC2", "Dimensions": [ { "Name": "InstanceId", "Value": "i-1234567890abcdef0" } ], "MetricName": "NetworkOut" }, { "Namespace": "AWS/EC2", "Dimensions": [ { "Name": "InstanceId", "Value": "i-1234567890abcdef0" } ], "MetricName": "CPUUtilization" }, { "Namespace": "AWS/EC2", "Dimensions": [ { "Name": "InstanceId", "Value": "i-1234567890abcdef0" } ], "MetricName": "NetworkIn" }, ... ] }

To list all the available metrics for an instance (AWS CLI)

The following example specifies the AWS/EC2 namespace and the InstanceId dimension to view the results for the specified instance only.

aws cloudwatch list-metrics --namespace AWS/EC2 --dimensions Name=InstanceId,Value=i-1234567890abcdef0

To list a metric across all instances (AWS CLI)

The following example specifies the AWS/EC2 namespace and a metric name to view the results for the specified metric only.

aws cloudwatch list-metrics --namespace AWS/EC2 --metric-name CPUUtilization