Alarm actions (SNS, Auto Scaling) in AWS - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to specify the SNS topic ARN for the alarm action.

AWS

AlarmActions: ["[1]"]

Drag options to blanks, or click blank then click option'

A"arn:aws:lambda:us-east-1:123456789012:function:MyFunction"

B"arn:aws:sqs:us-east-1:123456789012:MyQueue"

C"arn:aws:ec2:us-east-1:123456789012:instance/i-1234567890abcdef0"

D"arn:aws:sns:us-east-1:123456789012:MyTopic"

Attempts:

3 left

💡 Hint

Common Mistakes

Using an ARN for SQS, Lambda, or EC2 instead of SNS topic ARN.

The alarm action requires the ARN of an SNS topic to send notifications.

2fill in blank

medium

Complete the code to specify the Auto Scaling group name for the alarm action.

AWS

AutoScalingGroupName: "[1]"

Drag options to blanks, or click blank then click option'

AMyEC2Instance

BMyLambdaFunction

CMyAutoScalingGroup

DMySNSTopic

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing instance names or SNS topics with Auto Scaling group names.

The Auto Scaling alarm action requires the name of the Auto Scaling group to scale.

3fill in blank

hard

Fix the error in the alarm action configuration to correctly trigger scaling.

AWS

ScalingPolicyARN: "[1]"

Drag options to blanks, or click blank then click option'

A"arn:aws:autoscaling:us-east-1:123456789012:scalingPolicy:policy-id:autoScalingGroupName/MyAutoScalingGroup:policyName/MyPolicy"

B"arn:aws:sns:us-east-1:123456789012:MyTopic"

C"arn:aws:lambda:us-east-1:123456789012:function:MyFunction"

D"arn:aws:ec2:us-east-1:123456789012:instance/i-1234567890abcdef0"

Attempts:

3 left

💡 Hint

Common Mistakes

Using SNS topic ARN or Lambda ARN instead of Auto Scaling policy ARN.

The ScalingPolicyARN must point to an Auto Scaling policy ARN to trigger scaling actions.

4fill in blank

hard

Fill both blanks to configure an alarm that sends notification and triggers scaling.

AWS

AlarmActions: ["[1]", "[2]"]

Drag options to blanks, or click blank then click option'

A"arn:aws:sns:us-east-1:123456789012:NotifyTopic"

B"arn:aws:autoscaling:us-east-1:123456789012:scalingPolicy:policy-id:autoScalingGroupName/MyGroup:policyName/ScaleOut"

C"arn:aws:lambda:us-east-1:123456789012:function:MyFunction"

D"arn:aws:sqs:us-east-1:123456789012:MyQueue"

Attempts:

3 left

💡 Hint

Common Mistakes

Using Lambda or SQS ARNs instead of SNS or Auto Scaling policy ARNs.

The alarm can have multiple actions: one SNS notification and one Auto Scaling policy.

5fill in blank

hard

Fill all three blanks to define an alarm with threshold, SNS notification, and scaling policy.

AWS

Threshold: [1], AlarmActions: ["[2]", "[3]"]

Drag options to blanks, or click blank then click option'

A70

Barn:aws:sns:us-east-1:123456789012:AlertTopic

Carn:aws:autoscaling:us-east-1:123456789012:scalingPolicy:policy-id:autoScalingGroupName/Group1:policyName/ScaleIn

D80

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong threshold values or incorrect ARNs for alarm actions.

The threshold sets the alarm limit, and the actions include SNS notification and scaling policy ARNs.

Practice

1. What is the primary purpose of connecting an AWS CloudWatch alarm to an SNS topic?

easy

A. To create backups of alarm configurations

B. To send notifications when the alarm state changes

C. To store alarm history logs

D. To automatically scale EC2 instances

Solution

1. Step 1: Understand SNS topic role

   SNS topics are used to send messages or notifications to subscribers.

2. Step 2: Connect alarm to SNS for notifications

   When an alarm changes state, it can trigger SNS to notify users or systems.

3. Final Answer:

   To send notifications when the alarm state changes -> Option B

4. Quick Check:

   Alarm + SNS = Notifications [OK]

Hint: SNS topics send messages on alarm changes [OK]

Common Mistakes:

• Confusing SNS with Auto Scaling actions
• Thinking SNS stores logs
• Assuming SNS creates backups

2. Which of the following is the correct way to specify an Auto Scaling action in a CloudWatch alarm configuration?

easy

A. {
"AlarmActions": ["arn:aws:autoscaling:region:account-id:scalingPolicy:policy-id:autoScalingGroupName/group-name:policyName/policy-name"]
}

B. AlarmActions: ["arn:aws:sns:region:account-id:topic-name"]

C. AlarmActions: ["arn:aws:lambda:region:account-id:function:function-name"]

D. AlarmActions: ["arn:aws:s3:::bucket-name"]

Solution

1. Step 1: Identify correct ARN format for Auto Scaling policy

   Auto Scaling policy ARNs include 'autoscaling' and specify scalingPolicy and group name.

2. Step 2: Match with given options

   { "AlarmActions": ["arn:aws:autoscaling:region:account-id:scalingPolicy:policy-id:autoScalingGroupName/group-name:policyName/policy-name"] } matches the correct ARN format for Auto Scaling alarm action.

3. Final Answer:

   Correct Auto Scaling policy ARN format -> Option A

4. Quick Check:

   Auto Scaling action uses autoscaling ARN [OK]

Hint: Auto Scaling ARNs contain 'autoscaling' keyword [OK]

Common Mistakes:

• Using SNS ARN instead of Auto Scaling ARN
• Confusing Lambda or S3 ARNs as alarm actions
• Incorrect ARN structure

3. Given this CloudWatch alarm configuration snippet:

{
  "AlarmName": "HighCPU",
  "MetricName": "CPUUtilization",
  "Namespace": "AWS/EC2",
  "Threshold": 80,
  "ComparisonOperator": "GreaterThanThreshold",
  "EvaluationPeriods": 2,
  "AlarmActions": ["arn:aws:sns:us-east-1:123456789012:NotifyMe"]
}

What happens when the CPU utilization exceeds 80% for 2 evaluation periods?

medium

A. An SNS notification is sent to subscribers of the NotifyMe topic

B. The EC2 instance automatically scales up

C. The alarm resets without any action

D. A Lambda function is triggered

Solution

1. Step 1: Analyze AlarmActions ARN

   The AlarmActions list contains an SNS topic ARN, meaning notifications are sent on alarm.

2. Step 2: Understand alarm trigger

   When CPUUtilization > 80% for 2 periods, alarm state changes and triggers SNS notification.

3. Final Answer:

   An SNS notification is sent to subscribers of the NotifyMe topic -> Option A

4. Quick Check:

   Alarm with SNS ARN sends notifications [OK]

Hint: SNS ARN in AlarmActions means notification sent [OK]

Common Mistakes:

• Assuming Auto Scaling happens without scaling policy
• Thinking alarm resets silently
• Confusing SNS with Lambda triggers

4. You configured a CloudWatch alarm to trigger an Auto Scaling policy, but the instances are not scaling when the alarm state changes. What is the most likely cause?

medium

A. The EC2 instances are stopped

B. The SNS topic subscription is missing

C. The alarm threshold is set too low

D. The alarm's AlarmActions does not include the correct Auto Scaling policy ARN

Solution

1. Step 1: Check AlarmActions configuration

   If the Auto Scaling policy ARN is missing or incorrect, the alarm cannot trigger scaling.

2. Step 2: Rule out other options

   SNS subscription missing affects notifications, not scaling. Threshold too low triggers alarm but no scaling if policy missing. Stopped instances do not scale but alarm triggers still need correct action.

3. Final Answer:

   The alarm's AlarmActions does not include the correct Auto Scaling policy ARN -> Option D

4. Quick Check:

   Correct Auto Scaling ARN needed in AlarmActions [OK]

Hint: Auto Scaling needs correct policy ARN in AlarmActions [OK]

Common Mistakes:

• Confusing SNS subscription with scaling trigger
• Ignoring ARN correctness
• Assuming stopped instances auto scale

5. You want to automatically increase the number of EC2 instances when CPU usage is high and send a notification to your team. Which combination of alarm actions should you configure?

hard

A. Add only the Auto Scaling policy ARN to AlarmActions

B. Add only the SNS topic ARN to AlarmActions

C. Add both the Auto Scaling policy ARN and the SNS topic ARN to the alarm's AlarmActions

D. Create two separate alarms, one for scaling and one for notifications

Solution

1. Step 1: Understand alarm actions for scaling and notifications

   To scale automatically, the alarm must trigger the Auto Scaling policy. To notify, it must trigger the SNS topic.

2. Step 2: Combine both actions in one alarm

   Adding both ARNs in AlarmActions ensures the alarm triggers scaling and sends notifications simultaneously.

3. Final Answer:

   Add both the Auto Scaling policy ARN and the SNS topic ARN to the alarm's AlarmActions -> Option C

4. Quick Check:

   Multiple AlarmActions allow scaling + notifications [OK]

Hint: Use both Auto Scaling and SNS ARNs in AlarmActions [OK]

Common Mistakes:

• Thinking one ARN can do both scaling and notifications
• Creating multiple alarms unnecessarily
• Missing one of the required ARNs