Monitor CloudWatch metrics for your Auto Scaling groups and instances
Metrics are the fundamental concept in 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 publishes data points to CloudWatch about your Auto Scaling groups. The metrics are available at one-minute granularity at no additional charge, but you must enable them. By doing this, you get continuous visibility into the operations of your Auto Scaling groups so that you can quickly respond to changes in your workloads. You can enable and disable these metrics using the AWS Management Console, AWS CLI, or an SDK.
Amazon EC2 publishes data points to CloudWatch that describe your Auto Scaling instances. The interval for Amazon EC2 instance monitoring is configurable. You can choose between one-minute and five-minute granularity. For more information, see Configure monitoring for Auto Scaling instances.
Contents
Enable Auto Scaling group metrics (console)
When you enable Auto Scaling group metrics, your Auto Scaling group sends sampled data to CloudWatch every minute. There is no charge for enabling these metrics.
To enable group metrics
Open the Amazon EC2 Auto Scaling console at https://console.aws.amazon.com/ec2autoscaling/
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Select the check box next to your Auto Scaling group.
A split pane opens up in the bottom of the page.
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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
Open the Amazon EC2 Auto Scaling console at https://console.aws.amazon.com/ec2autoscaling/
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Select your Auto Scaling group.
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On the Monitoring tab, clear the Auto Scaling group metrics collection, Enable check box.
Enable Auto Scaling group metrics (AWS CLI)
To enable group metrics
Enable one or more group metrics using the enable-metrics-collection command. For example, the following command enables the GroupDesiredCapacity metric.
aws autoscaling enable-metrics-collection --auto-scaling-group-namemy-asg\ --metrics GroupDesiredCapacity --granularity "1Minute"
If you omit the --metrics option, all metrics are enabled.
aws autoscaling enable-metrics-collection --auto-scaling-group-namemy-asg\ --granularity "1Minute"
To disable group metrics
Use the disable-metrics-collection command. For example, the following command disables all Auto Scaling group metrics.
aws autoscaling disable-metrics-collection --auto-scaling-group-namemy-asg
Available metrics and dimensions
When group metrics are enabled, Amazon EC2 Auto Scaling sends the following metrics to CloudWatch.
CloudWatch group metrics are delivered on a best-effort basis. Data is not backfilled to fill gaps in group metric history in rare cases where CloudWatch is experiencing a service disruption.
Auto Scaling group metrics
The AWS/AutoScaling namespace includes the following metrics.
| 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 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 or pending. 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. |
The AWS/AutoScaling namespace includes the following metrics for Auto Scaling
groups that use the instance
weighting feature. If instance weighting is not applied, then the
following metrics are populated, but are equal to the metrics that are defined in
the preceding table.
| 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
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. |
GroupTotalCapacity
|
The total number of capacity units in the Auto Scaling group. Reporting criteria: Reported if metrics collection is enabled. |
The AWS/AutoScaling namespace includes the following metrics for Auto Scaling
groups that use the warm pools
feature.
| 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 Reporting criteria: Reported if metrics collection is enabled. |
WarmPoolPendingCapacity
|
The amount of capacity in the warm pool that is pending. This metric does not include instances that are running, stopped, or terminating. 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. |
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 Amazon EC2 Auto Scaling metrics
| Dimension | Description |
|---|---|
AutoScalingGroupName
|
Filters on the name of an Auto Scaling group. |
Work with Amazon CloudWatch
View CloudWatch metrics
You can view your Auto Scaling group metrics using the CloudWatch console and the command line tools.
To view metrics using the CloudWatch console
For more information, see Aggregating statistics by Auto Scaling group.
To view CloudWatch metrics (AWS CLI)
To view all metrics for all your Auto Scaling groups, use the following list-metrics command.
aws cloudwatch list-metrics --namespace "AWS/AutoScaling"
To view the metrics for a single Auto Scaling group, specify the
AutoScalingGroupName dimension as follows.
aws cloudwatch list-metrics --namespace "AWS/AutoScaling" --dimensions Name=AutoScalingGroupName,Value=my-asg
To view a single metric for all your Auto Scaling groups, specify the name of the metric as follows.
aws cloudwatch list-metrics --namespace "AWS/AutoScaling" --metric-name GroupDesiredCapacity
Create Amazon CloudWatch alarms
One purpose for monitoring metrics is to verify that your application is performing as expected. In Amazon CloudWatch, you can create an alarm that sends a notification when the value of a certain metric is beyond what you consider an acceptable threshold.
Start by identifying the metric to monitor. For example, you can configure an alarm to watch over the average CPU utilization of the EC2 instances in your Auto Scaling group. The action can be a notification that is sent to you when the average CPU utilization of the group's instances breaches the threshold that you specified for the consecutive periods you specified. For example, the metric stays at or above 70 percent for 4 consecutive periods of 1 minute each.
For more information, see Using Amazon CloudWatch alarms in the Amazon CloudWatch User Guide.
To create a CloudWatch alarm for your Auto Scaling group
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Open the CloudWatch console at https://console.aws.amazon.com/cloudwatch/
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If necessary, change the region. From the navigation bar, select the region where your Auto Scaling group resides.
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On the navigation pane, choose Alarms and then choose Create alarm.
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Choose Select metric.
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On the All metrics tab, select a metric as follows:
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To display only the metrics reported for your Auto Scaling groups, choose EC2, and then choose By Auto Scaling Group. To view the metrics for a single Auto Scaling group, type its name in the search field.
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Select the row that contains the metric for the Auto Scaling group that you want to create an alarm on.
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Choose Select metric. The Specify metric and conditions page appears, showing a graph and other information about the metric.
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For Period, choose the evaluation period for the alarm, for example, 1 minute. When evaluating the alarm, each period is aggregated into one data point.
Note A shorter period creates a more sensitive alarm.
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Under Conditions, do the following:
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For Threshold type, choose Static.
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For Whenever
metricis, specify whether you want the value of the metric to be greater than, greater than or equal to, less than, or less than or equal to the threshold to trigger the alarm. Then, under than, enter the threshold value that you want to trigger the alarm.
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Under Additional configuration, do the following:
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For Datapoints to alarm, enter the number of data points (evaluation periods) during which the metric value must meet the threshold conditions to trigger the alarm. For example, two consecutive periods of 5 minutes would take 10 minutes to trigger the alarm.
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For Missing data treatment, choose what you want the alarm to do if some data is missing. For more information, see Configuring how CloudWatch alarms treat missing data in the Amazon CloudWatch User Guide.
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Choose Next.
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Under Notification, you can choose or create the Amazon SNS topic you want to use to receive notifications. Otherwise, you can remove the notification now and add one later when you are ready.
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Choose Next.
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Enter a name and, optionally, a description for the alarm, and then choose Next.
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Choose Create Alarm.
