Why monitoring matters in AWS - Why It Works

Introduction

Monitoring helps you see how your cloud services and applications are working. It shows if something is wrong so you can fix it quickly before users notice.

When you want to know if your website is slow or down.

When you need to track how much memory or CPU your app is using.

When you want to get alerts if your database stops responding.

When you want to understand how many users are using your app at once.

When you want to improve your app by seeing which parts are slow or fail often.

Commands

This command creates an alarm in AWS CloudWatch that watches the CPU usage of an EC2 instance. It alerts you if CPU usage goes above 80% for two periods of 5 minutes each.

Terminal

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-0123456789abcdef0 --evaluation-periods 2 --alarm-actions arn:aws:sns:us-east-1:123456789012:MyTopic --unit Percent

Expected Output

No output (command runs silently)

→

--alarm-name - Name of the alarm to identify it easily

→

--threshold - The CPU usage percentage that triggers the alarm

→

--alarm-actions - The action to take when alarm triggers, like sending a notification

This command checks the status of the alarm you created to see if it is OK, in alarm, or insufficient data.

Terminal

aws cloudwatch describe-alarms --alarm-names HighCPUUtilization

Expected Output

{

    "MetricAlarms": [

        {

            "AlarmName": "HighCPUUtilization",

            "AlarmArn": "arn:aws:cloudwatch:us-east-1:123456789012:alarm:HighCPUUtilization",

            "StateValue": "OK",

            "StateReason": "Threshold Crossed: 1 datapoint [75.0 (12/06/24 10:00:00)] was not greater than the threshold (80.0).",

            "MetricName": "CPUUtilization"

        }

    ]

}

→

--alarm-names - Specify which alarm to describe

Key Concept

If you remember nothing else, remember: monitoring lets you catch problems early before they affect your users.

Common Mistakes

Setting alarm thresholds too high or too low without understanding normal usage

This causes false alarms or missed real problems, making monitoring useless or annoying

Check normal CPU or memory usage first, then set thresholds just above normal peaks

Not setting up alarm actions like notifications

You won't know when something goes wrong because no alert is sent

Always configure alarm actions to send emails or messages to your team

Summary

Create CloudWatch alarms to watch important metrics like CPU usage.

Check alarm status to know if your resources are healthy or need attention.

Set proper thresholds and notification actions to get useful alerts.

Practice

1. Why is monitoring important in AWS environments?

easy

A. It helps detect issues early to keep systems running smoothly.

B. It automatically fixes all system errors without human help.

C. It increases the cost of running AWS services.

D. It disables alarms to reduce notifications.

Solution

1. Step 1: Understand monitoring purpose

   Monitoring tracks system health and performance in real time.

2. Step 2: Identify the benefit of early detection

   Early detection helps fix problems before they affect users.

3. Final Answer:

   It helps detect issues early to keep systems running smoothly. -> Option A

4. Quick Check:

   Monitoring = Early issue detection [OK]

Hint: Monitoring = early alerts to avoid bigger problems [OK]

Common Mistakes:

• Thinking monitoring fixes issues automatically
• Believing monitoring increases costs unnecessarily
• Assuming monitoring disables alarms

2. Which AWS service is primarily used for monitoring and setting alarms?

easy

A. Amazon CloudWatch

B. Amazon EC2

C. AWS S3

D. AWS Lambda

Solution

1. Step 1: Identify AWS monitoring services

   AWS CloudWatch collects metrics and logs for monitoring.

2. Step 2: Match service to alarms and monitoring

   CloudWatch allows setting alarms to notify on issues.

3. Final Answer:

   Amazon CloudWatch -> Option A

4. Quick Check:

   Monitoring + alarms = CloudWatch [OK]

Hint: CloudWatch = AWS monitoring and alarms tool [OK]

Common Mistakes:

• Confusing Lambda with monitoring service
• Thinking S3 stores monitoring data directly
• Assuming EC2 handles alarms

3. What will happen if you create a CloudWatch alarm for CPU usage > 80% and the CPU usage reaches 85%?

medium

A. The CPU usage will automatically reduce.

B. The alarm will ignore the CPU usage.

C. The alarm will trigger and notify you.

D. The alarm will delete the instance.

Solution

1. Step 1: Understand CloudWatch alarm behavior

   Alarms trigger when the monitored metric crosses the threshold.

2. Step 2: Apply to CPU usage scenario

   CPU usage > 80% triggers the alarm at 85% usage.

3. Final Answer:

   The alarm will trigger and notify you. -> Option C

4. Quick Check:

   CPU > threshold = alarm triggers [OK]

Hint: Alarm triggers when metric exceeds threshold [OK]

Common Mistakes:

• Thinking alarms fix issues automatically
• Believing alarms ignore threshold breaches
• Assuming alarms delete resources

4. You set a CloudWatch alarm but never receive notifications when thresholds are crossed. What is a likely cause?

medium

A. The CPU usage never exceeded the threshold.

B. The alarm is not linked to any notification action.

C. CloudWatch does not support alarms.

D. The AWS account is inactive.

Solution

1. Step 1: Check alarm configuration

   Alarms must have notification actions (like SNS) to send alerts.

2. Step 2: Identify missing notification setup

   If no notification is linked, no alerts are sent despite threshold breaches.

3. Final Answer:

   The alarm is not linked to any notification action. -> Option B

4. Quick Check:

   Missing notification = no alerts [OK]

Hint: Link alarms to notifications to get alerts [OK]

Common Mistakes:

• Assuming alarms send notifications automatically
• Ignoring notification setup in alarm
• Thinking CloudWatch lacks alarm support

5. You want to keep your AWS app reliable by monitoring multiple metrics and sending alerts only when several conditions happen together. Which approach should you use?

hard

A. Create multiple independent CloudWatch alarms without combining them.

B. Disable alarms to reduce noise.

C. Rely on manual checks instead of alarms.

D. Use CloudWatch composite alarms to combine multiple alarms into one alert.

Solution

1. Step 1: Understand composite alarms

   Composite alarms combine multiple alarms using logical conditions.

2. Step 2: Apply composite alarms for multi-condition alerts

   This lets you alert only when all or some conditions happen together.

3. Final Answer:

   Use CloudWatch composite alarms to combine multiple alarms into one alert. -> Option D

4. Quick Check:

   Multi-condition alert = composite alarms [OK]

Hint: Use composite alarms for combined conditions [OK]

Common Mistakes:

• Creating separate alarms without combination
• Ignoring composite alarms feature
• Disabling alarms to avoid alerts