Create an alarm that uses a warm-up period

Create a metric alarm or log alarm with a warm-up period to delay evaluation after creation. For more information about warm-up periods, see Alarm warm-up periods.

Set the warm-up period with the WarmUpConfiguration parameter on the PutMetricAlarm API. Log alarms use the PutLogAlarm API.

Creating a warm-up alarm with the AWS CLI

The following examples create and manage alarms with warm-up periods.

Example Create a metric alarm with a 30-minute warm-up period

This alarm uses default early-termination behavior: it ends warm-up and begins to evaluate as soon as enough data fills the evaluation window.

aws cloudwatch put-metric-alarm \
  --alarm-name MyServiceStartupAlarm \
  --metric-name CPUUtilization \
  --namespace AWS/EC2 \
  --statistic Average \
  --period 300 \
  --evaluation-periods 1 \
  --threshold 80 \
  --comparison-operator GreaterThanThreshold \
  --dimensions Name=InstanceId,Value=i-1234567890abcdef0 \
  --warm-up-configuration '{"WarmUpPeriodDurationInMinutes":30}'

Example Wait the entire warm-up period before evaluating

Set OnlyStartEvaluatingAfterWarmUpPeriodEnds to true to prevent evaluation until the full warm-up duration elapses. The alarm waits the full 60 minutes before it evaluates, even if data arrives sooner.

aws cloudwatch put-metric-alarm \
  --alarm-name MyServiceStartupAlarm \
  --metric-name CPUUtilization \
  --namespace AWS/EC2 \
  --statistic Average \
  --period 300 \
  --evaluation-periods 1 \
  --threshold 80 \
  --comparison-operator GreaterThanThreshold \
  --dimensions Name=InstanceId,Value=i-1234567890abcdef0 \
  --warm-up-configuration '{"WarmUpPeriodDurationInMinutes":60,"OnlyStartEvaluatingAfterWarmUpPeriodEnds":true}'

Example Change the warm-up period while the alarm is warming up

You can update the warm-up configuration while the alarm is still in its warm-up period. This example sets the warm-up duration to 45 minutes.

aws cloudwatch put-metric-alarm \
  --alarm-name MyServiceStartupAlarm \
  --metric-name CPUUtilization \
  --namespace AWS/EC2 \
  --statistic Average \
  --period 300 \
  --evaluation-periods 1 \
  --threshold 80 \
  --comparison-operator GreaterThanThreshold \
  --dimensions Name=InstanceId,Value=i-1234567890abcdef0 \
  --warm-up-configuration '{"WarmUpPeriodDurationInMinutes":45}'

Note

After the warm-up period ends, you can update the warm-up configuration. However, the update does not start a new warm-up period. The alarm continues to evaluate normally.

View the warm-up configuration

Use the DescribeAlarms API to retrieve an alarm's warm-up configuration.

aws cloudwatch describe-alarms \
  --alarm-names MyServiceStartupAlarm

During warm-up, the alarm state remains INSUFFICIENT_DATA and the evaluation state is IN_WARM_UP.