# Monitor CloudWatch metrics for your Auto Scaling groups and instances
<a name="ec2-auto-scaling-cloudwatch-monitoring"></a>

*Metrics* are the fundamental concept in Amazon CloudWatch. A metric represents a time-ordered set of data points that are published to CloudWatch. Think of a metric as a variable to monitor, and the data points as representing the values of that variable over time. You can use these metrics to verify that your system is performing as expected. 

Amazon EC2 Auto Scaling metrics that collect information about Auto Scaling groups are in the `AWS/AutoScaling` namespace. Amazon EC2 instance metrics that collect CPU and other usage data from Auto Scaling instances are in the `AWS/EC2` namespace. 

The Amazon EC2 Auto Scaling console displays a series of graphs for the group metrics and the aggregated instance metrics for the group. Depending on your needs, you might prefer to access data for your Auto Scaling groups and instances from Amazon CloudWatch instead of the Amazon EC2 Auto Scaling console.

For more information, see the [Amazon CloudWatch User Guide](https://docs.aws.amazon.com/AmazonCloudWatch/latest/monitoring/).

**Topics**
+ [View monitoring graphs in the Amazon EC2 Auto Scaling console](viewing-monitoring-graphs.md)
+ [Amazon CloudWatch metrics for Amazon EC2 Auto Scaling](ec2-auto-scaling-metrics.md)
+ [Configure monitoring for Auto Scaling instances](enable-as-instance-metrics.md)

# View monitoring graphs in the Amazon EC2 Auto Scaling console
<a name="viewing-monitoring-graphs"></a>

In the Amazon EC2 Auto Scaling section of the Amazon EC2 console, you can monitor minute-by-minute progress of individual Auto Scaling groups using CloudWatch metrics. 

You can monitor the following types of metrics: 
+ **Auto Scaling metrics** – Auto Scaling metrics are turned on only when you enable them. For more information, see [Enable Auto Scaling group metrics (console)](ec2-auto-scaling-metrics.md#as-enable-group-metrics). When Auto Scaling metrics are enabled, the monitoring graphs show data published at one-minute granularity for Auto Scaling metrics.
+ **EC2 metrics** – The Amazon EC2 instance metrics are always enabled. When detailed monitoring is enabled, the monitoring graphs show data published at one-minute granularity for instance metrics. For more information, see [Configure monitoring for Auto Scaling instances](enable-as-instance-metrics.md). 

**To view monitoring graphs using the Amazon EC2 Auto Scaling console**

1. Open the Amazon EC2 console at [https://console.aws.amazon.com/ec2/](https://console.aws.amazon.com/ec2/), and choose **Auto Scaling Groups** from the navigation pane.

1. Select the check box next to the Auto Scaling group that you want to view metrics for. 

   A split pane opens up in the bottom part of the **Auto Scaling groups** page.

1. Choose the **Monitoring** tab.

   Amazon EC2 Auto Scaling displays monitoring graphs for **Auto Scaling** metrics.

1. To view monitoring graphs of the aggregated instance metrics for the group, choose **EC2**. 

 **Graph actions** 
+ Hover on a data point to view a data pop-up for a specific time in UTC. 
+ To enlarge a graph, choose **Enlarge** from the menu tool (the three vertical dots) in the upper right of the graph. Alternatively, choose the maximize icon at the top of the graph.
+ Adjust the time period for data displayed in the graph by selecting one of the predefined time period values. If the graph is enlarged, you can choose **Custom** to define your own time period.
+ Choose **Refresh** from the menu tool to update the data in a graph.
+ Drag your cursor over the graph data to select a specific range. You can then choose **Apply time range** in the menu tool.
+ Choose **View logs** from the menu tool to view associated log streams (if any) in the CloudWatch console.
+ To view a graph in CloudWatch, choose **View in metrics** from the menu tool. This takes you to the CloudWatch page for that graph. There, you can view more information or access historical information to gain a better understanding of how your Auto Scaling group changed over an extended period. 

## Graph metrics for your Auto Scaling groups
<a name="graph-metrics"></a>

After you create an Auto Scaling group, you can open the Amazon EC2 Auto Scaling console and view the monitoring graphs for the group on the **Monitoring** tab. 

In the **Auto Scaling** section, the graph metrics include the following metrics. These metrics provide measurements that can be indicators of a potential issue, such as number of terminating instances or number of pending instances. You can find definitions for these metrics in [Amazon CloudWatch metrics for Amazon EC2 Auto Scaling](ec2-auto-scaling-metrics.md).


| Display name | CloudWatch metric name | 
| --- | --- | 
|  Minimum Group Size |  GroupMinSize  | 
|  Maximum Group Size | GroupMaxSize  | 
|  Desired Capacity |  GroupDesiredCapacity  | 
|  In Service Instances |  GroupInServiceInstances  | 
|  Pending Instances |  GroupPendingInstances  | 
|  Standby Instances |  GroupStandbyInstances  | 
| Terminating Instances |  GroupTerminatingInstances  | 
| Total Instances |  GroupTotalInstances  | 

In the **EC2** section, you can find the following graph metrics based on key performance metrics for your Amazon EC2 instances. These EC2 metrics are an aggregate of metrics for all instances in the group. You can find definitions for these metrics in [List the available CloudWatch metrics for your instances](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/viewing_metrics_with_cloudwatch.html) in the *Amazon EC2 User Guide*. 


| Display name | CloudWatch metric name | 
| --- | --- | 
| CPU Utilization | CPUUtilization | 
| Disk Reads | DiskReadBytes | 
| Disk Read Operations | DiskReadOps | 
| Disk Writes | DiskWriteBytes | 
| Disk Write Operations | DiskWriteOps | 
| Network In | NetworkIn | 
| Network Out | NetworkOut | 
| Status Check Failed (Any) | StatusCheckFailed | 
| Status Check Failed (Instance) | StatusCheckFailed\$1Instance | 
| Status Check Failed (System) | StatusCheckFailed\$1System | 

In addition, some metrics are available for specific use cases in the **Auto Scaling** graph metrics.

The following metrics are useful if your group uses weights that define how many units each instance contributes to the desired capacity of the group. You can find definitions for these metrics in [Amazon CloudWatch metrics for Amazon EC2 Auto Scaling](ec2-auto-scaling-metrics.md).


| Display name | CloudWatch metric name | 
| --- | --- | 
|  In Service Capacity Units | GroupInServiceCapacity | 
| Pending Capacity Units | GroupPendingCapacity | 
| Standby Capacity Units | GroupStandbyCapacity | 
| Terminating Capacity Units | GroupTerminatingCapacity | 
| Total Capacity Units | GroupTotalCapacity | 

The following metrics are useful if your group uses the [warm pool](ec2-auto-scaling-warm-pools.md) feature. You can find definitions for these metrics in [Amazon CloudWatch metrics for Amazon EC2 Auto Scaling](ec2-auto-scaling-metrics.md).


| Display name | CloudWatch metric name | 
| --- | --- | 
| Warm Pool Minimum Size | WarmPoolMinSize | 
| Warm Pool Desired Capacity | WarmPoolDesiredCapacity | 
| Warm Pool Pending Capacity Units | WarmPoolPendingCapacity | 
| Warm Pool Terminating Capacity Units | WarmPoolTerminatingCapacity | 
| Warm Pool Warmed Capacity Units | WarmPoolWarmedCapacity | 
| Warm Pool Total Capacity Units Launched | WarmPoolTotalCapacity | 
| Group and Warm Pool Desired Capacity | GroupAndWarmPoolDesiredCapacity | 
| Group and Warm Pool Total Capacity Units Launched | GroupAndWarmPoolTotalCapacity | 

### Related resources
<a name="graph-metrics-related-resources"></a>
+ To monitor per-instance metrics, see [Graph metrics for your instances](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/graphs-in-the-aws-management-console.html) in the *Amazon EC2 User Guide*. 
+ CloudWatch dashboards are customizable home pages in the CloudWatch console. You can use these pages to monitor your resources in a single view, even including resources that are spread across different Regions. You can use CloudWatch dashboards to create customized views of the metrics and alarms for your AWS resources. For more information, see the [Amazon CloudWatch User Guide](https://docs.aws.amazon.com/AmazonCloudWatch/latest/monitoring/).

# Amazon CloudWatch metrics for Amazon EC2 Auto Scaling
<a name="ec2-auto-scaling-metrics"></a>

Amazon EC2 Auto Scaling publishes the following metrics in the `AWS/AutoScaling` namespace. The actual Auto Scaling group metrics made available will depend on whether you have group metrics enabled, and which group metrics you enabled. Group metrics are available at one-minute granularity at no additional charge, but you must enable them.

When you enable Auto Scaling group metrics, Amazon EC2 Auto Scaling sends sampled data to CloudWatch every minute on a best-effort basis. In rare cases when CloudWatch experiences a service disruption, data isn't backfilled to fill gaps in group metric history.

**Topics**
+ [Auto Scaling group metrics](#as-group-metrics)
+ [Dimensions for Auto Scaling group metrics](#as-group-metric-dimensions)
+ [Predictive scaling metrics and dimensions](#predictive-scaling-metrics)
+ [Enable Auto Scaling group metrics (console)](#as-enable-group-metrics)
+ [Enable Auto Scaling group metrics (AWS CLI)](#as-enable-group-metrics-cli)

## Auto Scaling group metrics
<a name="as-group-metrics"></a>

With these metrics, you get nearly continuous visibility into the history of your Auto Scaling group, such as changes in the size of the group over time.


| Metric | Description | 
| --- | --- | 
|  GroupMinSize  |  The minimum size of the Auto Scaling group. **Reporting criteria**: Reported if metrics collection is enabled.  | 
|  GroupMaxSize  |  The maximum size of the Auto Scaling group. **Reporting criteria**: Reported if metrics collection is enabled.  | 
|  GroupDesiredCapacity  |  The number of instances that the Auto Scaling group attempts to maintain. **Reporting criteria**: Reported if metrics collection is enabled.  | 
|  GroupInServiceInstances  |  The number of instances that are running as part of the Auto Scaling group. This metric does not include instances that are pending or terminating. **Reporting criteria**: Reported if metrics collection is enabled.  | 
|  GroupPendingInstances  |  The number of instances that are pending. A pending instance is not yet in service. This metric does not include instances that are in service or terminating. **Reporting criteria**: Reported if metrics collection is enabled.  | 
|  GroupStandbyInstances  |  The number of instances that are in a `Standby` state. Instances in this state are still running but are not actively in service. **Reporting criteria**: Reported if metrics collection is enabled.  | 
|  GroupTerminatingInstances  |  The number of instances that are in the process of terminating. This metric does not include instances that are in service, pending, or returning to a warm pool after Auto Scaling group scale in. **Reporting criteria**: Reported if metrics collection is enabled.  | 
|  GroupTerminatingRetainedInstances  |  The number of instances in the `Terminating:Retained` state. **Reporting criteria**: Reported if metrics collection is enabled.  | 
|  GroupTotalInstances  |  The total number of instances in the Auto Scaling group. This metric identifies the number of instances that are in service, pending, and terminating. **Reporting criteria**: Reported if metrics collection is enabled.  | 

When you configure a mixed instances group to measure its desired capacity in different units, such as by assigning weights based on the vCPU count of each instance type, the following metrics count the number of units used by your Auto Scaling group. If you did not configure a mixed instances group to measure its desired capacity in different units, then the following metrics are populated, but are equal to the metrics that are defined in the previous table. For more information, see [Setup overview for creating a mixed instances group](mixed-instances-groups-set-up-overview.md). 


| Metric | Description | 
| --- | --- | 
|  GroupInServiceCapacity  |  The number of capacity units that are running as part of the Auto Scaling group.  **Reporting criteria**: Reported if metrics collection is enabled.  | 
|  GroupPendingCapacity  |  The number of capacity units that are pending.  **Reporting criteria**: Reported if metrics collection is enabled.  | 
|  GroupStandbyCapacity  |  The number of capacity units that are in a `Standby` state. **Reporting criteria**: Reported if metrics collection is enabled.  | 
|  GroupTerminatingCapacity  |  The number of capacity units that are in the process of terminating.  **Reporting criteria**: Reported if metrics collection is enabled.  | 
|  GroupTerminatingRetainedCapacity  |  The capacity units represented by instances in the `Terminating:Retained` state. **Reporting criteria**: Reported if metrics collection is enabled.  | 
|  GroupTotalCapacity  |  The total number of capacity units in the Auto Scaling group. **Reporting criteria**: Reported if metrics collection is enabled.  | 

Amazon EC2 Auto Scaling also reports the following metrics for Auto Scaling groups that have a warm pool. For more information, see [Decrease latency for applications with long boot times using warm pools](ec2-auto-scaling-warm-pools.md).


| Metric | Description | 
| --- | --- | 
|  WarmPoolMinSize  |  The minimum size of the warm pool.  **Reporting criteria**: Reported if metrics collection is enabled.  | 
|  WarmPoolDesiredCapacity  |  The amount of capacity that Amazon EC2 Auto Scaling attempts to maintain in the warm pool.  This is equivalent to the maximum size of the Auto Scaling group minus its desired capacity, or, if set, as the maximum prepared capacity of the Auto Scaling group minus its desired capacity. However, when the minimum size of the warm pool is equal to or greater than the difference between the maximum size (or, if set, the maximum prepared capacity) and the desired capacity of the Auto Scaling group, then the warm pool desired capacity will be equivalent to the `WarmPoolMinSize`. **Reporting criteria**: Reported if metrics collection is enabled.  | 
|  WarmPoolPendingCapacity  |  The amount of capacity in the warm pool that is pending. This includes instances returning to a warm pool after Auto Scaling group scale in. This metric does not include instances that are running, stopped, or terminating. **Reporting criteria**: Reported if metrics collection is enabled.  | 
|  WarmPoolPendingRetainedCapacity  |  Tracks retained instances returning to the warm pool. **Reporting criteria**: Reported if metrics collection is enabled.  | 
|  WarmPoolTerminatingCapacity  |  The amount of capacity in the warm pool that is in the process of terminating. This metric does not include instances that are running, stopped, or pending.  **Reporting criteria**: Reported if metrics collection is enabled.  | 
|  WarmPoolTerminatingRetainedCapacity  |  Tracks retained instances terminating from the warm pool. **Reporting criteria**: Reported if metrics collection is enabled.  | 
|  WarmPoolWarmedCapacity  |  The amount of capacity available to enter the Auto Scaling group during scale out. This metric does not include instances that are pending or terminating.  **Reporting criteria**: Reported if metrics collection is enabled.  | 
|  WarmPoolTotalCapacity  |  The total capacity of the warm pool, including instances that are running, stopped, pending, or terminating.  **Reporting criteria**: Reported if metrics collection is enabled.  | 
|  GroupAndWarmPoolDesiredCapacity  |  The desired capacity of the Auto Scaling group and the warm pool combined. **Reporting criteria**: Reported if metrics collection is enabled.  | 
|  GroupAndWarmPoolTotalCapacity  |  The total capacity of the Auto Scaling group and the warm pool combined. This includes instances that are running, stopped, pending, terminating, or in service.  **Reporting criteria**: Reported if metrics collection is enabled.  | 

## Dimensions for Auto Scaling group metrics
<a name="as-group-metric-dimensions"></a>

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


| Dimension | Description | 
| --- | --- | 
|  AutoScalingGroupName  |  Filters on the name of an Auto Scaling group.  | 

## Predictive scaling metrics and dimensions
<a name="predictive-scaling-metrics"></a>

The `AWS/AutoScaling` namespace includes the following metrics for predictive scaling. 

Metrics are available with a resolution of one hour.

You can evaluate forecast accuracy by comparing forecasted values with actual values. For more information about evaluating forecast accuracy using these metrics, see [Monitor predictive scaling metrics with CloudWatch](monitor-predictive-scaling-cloudwatch.md).


| Metric | Description | Dimensions | 
| --- | --- | --- | 
|  PredictiveScalingLoadForecast  |  The amount of load that's anticipated to be generated by your application. The `Average`, `Minimum`, and `Maximum` statistics are useful, but the `Sum` statistic is not.  **Reporting criteria**: Reported after the initial forecast is created.  | AutoScalingGroupName, PolicyName, PairIndex  | 
| PredictiveScalingCapacityForecast |  The anticipated amount of capacity needed to meet application demand. This is based on the load forecast and target utilization level at which you want to maintain your Auto Scaling instances. The `Average`, `Minimum`, and `Maximum` statistics are useful, but the `Sum` statistic is not. **Reporting criteria**: Reported after the initial forecast is created.  | AutoScalingGroupName, PolicyName | 
| PredictiveScalingMetricPairCorrelation |  The correlation between the scaling metric and the per-instance average of the load metric. Predictive scaling assumes high correlation. Therefore, if you observe low value for this metric, it's better not to use a metric pair. The `Average`, `Minimum`, and `Maximum` statistics are useful, but the `Sum` statistic is not. **Reporting criteria**: Reported after the initial forecast is created.  | AutoScalingGroupName, PolicyName, PairIndex | 

**Note**  
The `PairIndex` dimension returns information associated with the index of the load-scaling metric pair as assigned by Amazon EC2 Auto Scaling. Currently, the only valid value is `0`. 

## Enable Auto Scaling group metrics (console)
<a name="as-enable-group-metrics"></a>

**To enable group metrics**

1. Open the Amazon EC2 console at [https://console.aws.amazon.com/ec2/](https://console.aws.amazon.com/ec2/), and choose **Auto Scaling Groups** from the navigation pane.

1. Select the check box next to your Auto Scaling group.

   A split pane opens up in the bottom of the page. 

1. On the **Monitoring** tab, select the **Auto Scaling group metrics collection**, **Enable** check box located at the top of the page under **Auto Scaling**. 

**To disable group metrics**

1. Open the Amazon EC2 console at [https://console.aws.amazon.com/ec2/](https://console.aws.amazon.com/ec2/), and choose **Auto Scaling Groups** from the navigation pane.

1. Select your Auto Scaling group.

1. On the **Monitoring** tab, clear the **Auto Scaling group metrics collection**, **Enable** check box. 

## Enable Auto Scaling group metrics (AWS CLI)
<a name="as-enable-group-metrics-cli"></a>

**To enable Auto Scaling group metrics**  
Enable one or more group metrics by using the [enable-metrics-collection](https://awscli.amazonaws.com/v2/documentation/api/latest/reference/autoscaling/enable-metrics-collection.html) command. For example, the following command enables a single metric for the specified Auto Scaling group.

```
aws autoscaling enable-metrics-collection --auto-scaling-group-name my-asg \
  --metrics GroupDesiredCapacity --granularity "1Minute"
```

If you omit the `--metrics` option, all metrics are enabled.

```
aws autoscaling enable-metrics-collection --auto-scaling-group-name my-asg \
  --granularity "1Minute"
```

**To disable Auto Scaling group metrics**  
Use the [disable-metrics-collection](https://awscli.amazonaws.com/v2/documentation/api/latest/reference/autoscaling/disable-metrics-collection.html) command to disable all group metrics.

```
aws autoscaling disable-metrics-collection --auto-scaling-group-name my-asg
```

# Configure monitoring for Auto Scaling instances
<a name="enable-as-instance-metrics"></a>

Amazon EC2 collects and processes raw data from instances into readable, near real-time metrics that describe the CPU and other usage data for your Auto Scaling group. You can configure the interval for monitoring these metrics by choosing one-minute or five-minute granularity. 

Instance monitoring is enabled whenever an instance is launched, using either basic monitoring (five-minute granularity) or detailed monitoring (one-minute granularity). For detailed monitoring, additional charges apply. For more information, see [Amazon CloudWatch pricing](https://aws.amazon.com/cloudwatch/pricing/) and [Monitoring your instances using CloudWatch](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/using-cloudwatch.html) in the *Amazon EC2 User Guide*.

Before creating an Auto Scaling group, you should create a launch template or launch configuration that permits the type of monitoring that is appropriate to your application. If you add a scaling policy to your group, we strongly recommend that you use detailed monitoring to get metric data for EC2 instances at a one-minute granularity, because that achieves a faster response to changes in load.

**Topics**
+ [Enable detailed monitoring (console)](#enable-detailed-monitoring-console)
+ [Enable detailed monitoring (AWS CLI)](#enable-detailed-monitoring-cli)
+ [Switch between basic and detailed monitoring](#change-monitoring)
+ [Collect additional metrics using the CloudWatch agent](#metrics-collected-by-cloudwatch-agent)

## Enable detailed monitoring (console)
<a name="enable-detailed-monitoring-console"></a>

By default, basic monitoring is enabled when you use the AWS Management Console to create a launch template or launch configuration. 

**To enable detailed monitoring in a launch template**  
When you create the launch template using the AWS Management Console, in the **Advanced details** section, for **Detailed CloudWatch monitoring**, choose **Enable**. Otherwise, basic monitoring is enabled. For more information, see [Create a launch template using advanced settings](advanced-settings-for-your-launch-template.md).

**To enable detailed monitoring in a launch configuration**  
When you create the launch configuration using the AWS Management Console, in the **Additional configuration** section, select **Enable EC2 instance detailed monitoring within CloudWatch**. Otherwise, basic monitoring is enabled. For more information, see [Create a launch configuration](create-launch-config.md).

## Enable detailed monitoring (AWS CLI)
<a name="enable-detailed-monitoring-cli"></a>

By default, basic monitoring is enabled when you create a launch template using the AWS CLI. Detailed monitoring is enabled by default when you create a launch configuration using the AWS CLI. 

**To enable detailed monitoring in a launch template**  
For launch templates, use the [create-launch-template](https://awscli.amazonaws.com/v2/documentation/api/latest/reference/ec2/create-launch-template.html) command and pass a JSON file that contains the information for creating the launch template. Set the monitoring attribute to `"Monitoring":{"Enabled":true}` to enable detailed monitoring or `"Monitoring":{"Enabled":false}` to enable basic monitoring. 

**To enable detailed monitoring in a launch configuration**  
For launch configurations, use the [create-launch-configuration](https://awscli.amazonaws.com/v2/documentation/api/latest/reference/autoscaling/create-launch-configuration.html) command with the `--instance-monitoring` option. Set this option to `true` to enable detailed monitoring or `false` to enable basic monitoring.

```
--instance-monitoring Enabled=true
```

## Switch between basic and detailed monitoring
<a name="change-monitoring"></a>

To change the type of monitoring enabled on new EC2 instances, update the launch template or update the Auto Scaling group to use a new launch template or launch configuration. Existing instances continue to use the previously enabled monitoring type. To update all instances, terminate them so that they are replaced by your Auto Scaling group or update instances individually using [monitor-instances](https://awscli.amazonaws.com/v2/documentation/api/latest/reference/ec2/monitor-instances.html) and [unmonitor-instances](https://awscli.amazonaws.com/v2/documentation/api/latest/reference/ec2/unmonitor-instances.html).

**Note**  
With the instance refresh and maximum instance lifetime features, you can also replace all instances in the Auto Scaling group to launch new instances that use the new settings. For more information, see [Replace the instances in your Auto Scaling group](ec2-auto-scaling-group-replacing-instances.md).

When you switch between basic and detailed monitoring:

If you have CloudWatch alarms associated with the step scaling policies or simple scaling policies for your Auto Scaling group, use the [put-metric-alarm](https://awscli.amazonaws.com/v2/documentation/api/latest/reference/cloudwatch/put-metric-alarm.html) command to update each alarm. Make each period match the monitoring type (300 seconds for basic monitoring and 60 seconds for detailed monitoring). If you change from detailed monitoring to basic monitoring but do not update your alarms to match the five-minute period, they continue to check for statistics every minute. They might find no data available for as many as four out of every five periods.

## Collect additional metrics using the CloudWatch agent
<a name="metrics-collected-by-cloudwatch-agent"></a>

To collect operating system-level metrics like available and used memory, you must install the CloudWatch agent. Additional fees may apply. You can use the CloudWatch agent to collect both system metrics and log files from Amazon EC2 instances. For more information, see [Metrics collected by the CloudWatch agent](https://docs.aws.amazon.com/AmazonCloudWatch/latest/monitoring/metrics-collected-by-CloudWatch-agent.html) in the *Amazon CloudWatch User Guide*.