[Solved] Given this EventBridge rule JSON snippet, what will happen when an EC2 instance state... Given this EventBridge rule JSON snippet, what will happen when an EC2 instance state changes to 'stopped'? | AWS

AWS - CloudWatch

Given this EventBridge rule JSON snippet, what will happen when an EC2 instance state changes to 'stopped'?

{
  "Source": ["aws.ec2"],
  "DetailType": ["EC2 Instance State-change Notification"],
  "Detail": {"state": ["stopped"]}
}

AThe rule triggers only when an EC2 instance stops

BThe rule triggers for any EC2 state change

CThe rule triggers only when an EC2 instance starts

DThe rule never triggers

Step-by-Step Solution

Solution:

Step 1: Analyze event pattern
The pattern filters events from source 'aws.ec2' with detail type 'EC2 Instance State-change Notification' and detail state 'stopped'.
Step 2: Understand filtering effect
Only events where the instance state changes to 'stopped' match this pattern, so the rule triggers only then.
Final Answer:
The rule triggers only when an EC2 instance stops -> Option A
Quick Check:
Detail state filter 'stopped' triggers only on stop = A [OK]

Quick Trick: Detail filters limit triggers to specific event states [OK]

Common Mistakes:

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Given this EventBridge rule JSON snippet, what will happen when an EC2 instance state changes to 'stopped'?