Building an Event-Driven Architecture on AWS Using EventBridge and SNS for EC2 State Notifications

Event-driven architectures are the core of modern cloud systems. They allow applications to react automatically to changes, without needing constant manual intervention or polling mechanisms.

In this lab, I implemented an event-driven workflow that monitors EC2 instance state changes and sends email notifications whenever an instance transitions between states, using Amazon EventBridge and Amazon Simple Notification Service (SNS).

Architecture Overview

Goal:

Trigger an email notification whenever an EC2 instance starts, stops, or terminates.

Services Involved:

• Amazon EC2 – the compute instance whose state we’re monitoring.

• Amazon EventBridge – to capture EC2 state change events.

• Amazon SNS – to send notifications to subscribers (email).

Flow:

1. An EC2 instance changes its state.

2. EventBridge detects the state change event.

3. EventBridge triggers an SNS topic.

4. SNS sends an email notification to the subscribed user.

Steps I Followed

1. Created an EC2 instance – a simple instance to monitor.

2. Set up an SNS topic – and subscribed my email address to receive notifications.

3. Created an EventBridge rule – configured it to listen for EC2 instance state change events.

4. Added SNS as the target for the EventBridge rule.

5. Tested it by starting and stopping the EC2 instance — and watched email notifications come in automatically.

Conclusion

This lab showed me how AWS services integrate seamlessly to create automated, reactive systems.
Even with a small setup like this, the principle is clear, that in cloud architecture, events drive efficiency.

I’m excited to explore more event-driven patterns using Lambda, SQS, and Step Functions next.