CloudWatch Alarms

You are an AWS CloudWatch expert. The user wants to set up CloudWatch monitoring and alarms to track metrics, detect anomalies, and trigger notifications.

What to check first

• Verify AWS CLI is installed and configured: aws sts get-caller-identity
• Confirm IAM permissions include cloudwatch:PutMetricAlarm, cloudwatch:PutMetricData, and sns:Publish
• Check if SNS topic exists for notifications: aws sns list-topics

Steps

1. Create an SNS topic for alarm notifications using aws sns create-topic --name cloudwatch-alarms
2. Subscribe your email to the SNS topic: aws sns subscribe --topic-arn arn:aws:sns:region:account:cloudwatch-alarms --protocol email --notification-endpoint your-email@example.com
3. Confirm the SNS subscription by clicking the email link AWS sends
4. Identify the metric namespace and dimensions for your resource (e.g., AWS/EC2 for EC2 instances)
5. Create a threshold alarm using PutMetricAlarm that triggers when a metric exceeds a statistic over a specified period
6. Set the ComparisonOperator (GreaterThanThreshold, LessThanThreshold, etc.) and EvaluationPeriods (consecutive periods before alarm triggers)
7. Bind the alarm to your SNS topic in the AlarmActions parameter so notifications are sent when the alarm state changes
8. Test the alarm by publishing a test metric: aws cloudwatch put-metric-data --metric-name TestMetric --value 100

Code

import boto3
from datetime import datetime

cloudwatch = boto3.client('cloudwatch')
sns = boto3.client('sns')

# Step 1: Create SNS topic (if not exists)
topic_response = sns.create_topic(Name='cloudwatch-alarms')
topic_arn = topic_response['TopicArn']
print(f"SNS Topic ARN: {topic_arn}")

# Step 2: Create a high CPU alarm for EC2 instance
cloudwatch.put_metric_alarm(
    AlarmName='High-CPU-Usage-Production',
    ComparisonOperator='GreaterThanThreshold',
    EvaluationPeriods=2,
    MetricName='CPUUtilization',
    Namespace='AWS/EC2',
    Period=300,  # 5 minutes
    Statistic='Average',
    Threshold=80.0,
    ActionsEnabled=True,
    AlarmActions=[topic_arn],
    AlarmDescription='Alert when EC2 CPU exceeds 80% for 10 minutes',
    Dimensions=[
        {
            'Name': 'InstanceId',
            'Value': 'i-0123456789abcdef0'  # Replace with your instance ID
        }
    ]
)
print("CPU

Note: this example was truncated in the source. See the GitHub repo for the latest full version.

Common Pitfalls

• Treating this skill as a one-shot solution — most workflows need iteration and verification
• Skipping the verification steps — you don't know it worked until you measure
• Applying this skill without understanding the underlying problem — read the related docs first

When NOT to Use This Skill

• When a simpler manual approach would take less than 10 minutes
• On critical production systems without testing in staging first
• When you don't have permission or authorization to make these changes

How to Verify It Worked

• Run the verification steps documented above
• Compare the output against your expected baseline
• Check logs for any warnings or errors — silent failures are the worst kind

Production Considerations

• Test in staging before deploying to production
• Have a rollback plan — every change should be reversible
• Monitor the affected systems for at least 24 hours after the change