Sharing Events Across AWS Accounts with EventBridge: A Step-by-Step Guide

Introduction

In the realm of event-driven architectures, AWS EventBridge plays a pivotal role in facilitating seamless communication between services. One powerful capability it offers is the ability to share events across AWS accounts. This feature becomes particularly valuable when considering the integration of applications spread across different AWS environments.

Use Case: Application Integration

The Power of Shared Events

Imagine a scenario where two AWS accounts host different components of a larger application. Account A manages a user authentication service, while Account B handles transaction processing. Sharing events between these accounts allows for real-time communication, ensuring that transaction events trigger necessary actions in the user authentication service. This use case exemplifies the efficiency and responsiveness gained through cross-account event sharing.

Security Concerns and Best Practices

Prioritizing Security in Cross-Account Event Sharing

1. IAM Role Configuration:

   - Create IAM roles with the least privilege principle. Assign only the necessary permissions for cross-account communication.

2. Use Secure Protocols:

   - When transmitting events between accounts, prioritize secure protocols. HTTPS is recommended for ensuring data confidentiality.

3. Event Filtering:

   - Implement event filtering to only allow specific event types to be shared. This reduces the risk of unintended data exposure.

Step-by-Step Walkthrough

1. Set Up IAM Roles

Begin by creating IAM roles in both the source and target AWS accounts.

In the source account:

- Navigate to the IAM console.

- Create a new role with the necessary permissions for EventBridge event sending.

- Attach a trust policy allowing the target account to assume this role.

In the target account:

- Create a new role with permissions for receiving events.

- Attach a trust policy allowing the source account to assume this role.

2. Set Up EventBridge in the Source Account

In the AWS EventBridge console of the source account:

- Create a new rule.

- Specify the event publish permission to target event bus by specifing the ARN.

- Specify the eventbridge service in trust policy (Who can assume this role).

3. Set Up EventBridge in the Target Account

In the AWS EventBridge console of the target account:

- Create a new rule to receive events.

- Define the event pattern rule to contains Account field with the source account id and other patterns  as needed.

- Update the EventBridge resource policy to allow event publishing from source account by specifing the role ARN created in the step "Set Up EventBridge in the Source Account"

4. Testing the Integration

To ensure the setup is working as expected:

- Trigger events in the source account.

- Verify that these events are received and processed in the target account.

Conclusion

In conclusion, sharing events across AWS accounts with EventBridge opens up a realm of possibilities for application integration. However, this power must be wielded responsibly, with a keen focus on security considerations. By following best practices and employing a careful configuration process, developers can leverage the full potential of cross-account event sharing.

As you embark on your journey of event-driven architectures, remember that this guide serves as a foundation. Experiment, iterate, and tailor these steps to your specific use cases. 

Happy event sharing across AWS accounts!