Amazon EventBridge

Exam relevance: Domains 2, 3. EventBridge is the event routing backbone. Know event buses, rules, pipes, scheduler, and cross-account patterns.

1. Overview

Amazon EventBridge is a serverless event bus that connects AWS services, SaaS applications, and custom applications using events. It enables loosely coupled, event-driven architectures.

2. Event Buses

3. Rules

Rules match incoming events and route them to targets:

{
  "source": ["aws.ec2"],
  "detail-type": ["EC2 Instance State-change Notification"],
  "detail": {
    "state": ["terminated"]
  }
}

• Up to 5 targets per rule
• Targets: Lambda, SQS, SNS, Step Functions, Kinesis, API Gateway, ECS, CodePipeline, and more
• Input transformation: modify event before sending to target
• Dead-letter queue: capture failed event deliveries

4. EventBridge Pipes

Point-to-point integration between a source and a target with optional filtering and enrichment:

Source (SQS, DynamoDB Streams, Kinesis, Kafka)
    └── Filter (optional)
            └── Enrichment (Lambda, Step Functions, API Gateway)
                    └── Target (Lambda, SQS, SNS, Step Functions, etc.)

• Reduces boilerplate Lambda code for simple source-to-target integrations
• Built-in batching and filtering
• Supports enrichment step for data transformation

5. EventBridge Scheduler

Create scheduled tasks at scale:

• Rate-based: every N minutes/hours/days
• Cron-based: specific times (cron expressions)
• One-time: single future execution
• Supports flexible time windows (run within a window, not exactly at time)
• Targets: any AWS service API (Lambda, SQS, Step Functions, ECS, etc.)
• Scales to millions of schedules

6. Cross-Account Event Routing

Account A (producer)
  └── Custom event bus → EventBridge rule → sends to Account B event bus

Account B (consumer)
  └── Custom event bus → rule → Lambda/SQS/etc.

• Add resource-based policy to the target event bus allowing the source account
• Enables centralized event processing across an organization

7. Schema Registry

• Automatically discovers and stores event schemas
• Generate code bindings (Java, Python, TypeScript) from schemas
• Enables type-safe event handling in applications

8. Exam Scenarios

Scenario 1: A company wants to trigger a Lambda function whenever an EC2 instance is terminated in any account in the organization. What is the solution?

Create an EventBridge rule on the default event bus in each account matching EC2 termination events. Route events to a central event bus in the security account using cross-account event routing. Create a rule on the central bus to trigger Lambda.

Scenario 2: A company wants to process DynamoDB Stream records, filter out irrelevant events, enrich with additional data from an API, and send to SQS. What is the cleanest solution?

Use EventBridge Pipes. Configure DynamoDB Streams as the source, add a filter for relevant events, use an API Gateway enrichment step, and SQS as the target. No Lambda boilerplate code needed.

Scenario 3: A company needs to run a database cleanup job every Sunday at 2 AM UTC. What is the solution?

Use EventBridge Scheduler with a cron expression (cron(0 2 ? * SUN *)). Target a Lambda function or ECS task. Scheduler handles the scheduling infrastructure — no EC2 cron jobs needed.

9. Exam Tips

• Default bus = AWS service events; Custom bus = application events
• EventBridge is push-based — events are delivered to targets (unlike SQS which is pull-based)
• Pipes = point-to-point with filter + enrichment; Rules = fan-out to multiple targets
• Scheduler = millions of schedules, flexible time windows — replaces CloudWatch Events scheduled rules
• Cross-account routing requires resource policy on the target event bus
• EventBridge has at-least-once delivery — design targets to be idempotent

10. Official References

• EventBridge User Guide
• EventBridge Pipes
• EventBridge Scheduler
• Cross-Account Events