You can set up a CloudWatch alarm using the AWS Management Console, AWS CLI, or SDKs. Here’s an example using the AWS CLI:
aws cloudwatch put-metric-alarm \
--alarm-name HighCPUUtilization \
--metric-name CPUUtilization \
--namespace AWS/EC2 \
--statistic Average \
--period 300 \
--threshold 80 \
--comparison-operator GreaterThanThreshold \
--dimensions Name=InstanceId,Value=i-1234567890abcdef0 \
--evaluation-periods 1 \
--alarm-actions arn:aws:sns:us-west-2:123456789012:NotifyMe
This command sets up an alarm named HighCPUUtilization that triggers when the average CPU utilization of the specified EC2 instance exceeds 80% over a 5-minute period.