Day 4: EventBridge — Rules, Patterns, and Targets

Phase 5 · Aug 15, 2026

Agenda (2–3 hours)

• Read (45 min): AWS EventBridge Developer Guide: event buses, rules, patterns, targets, event replay
• Study (45 min): Compare EventBridge vs SNS vs SQS: when does each service fit?
• Practice (45 min): Create a custom event bus; define three rules with pattern matching; route events to Lambda, SQS, and Step Functions targets
• Challenge (30 min): EventBridge supports 20+ AWS service event sources. Design an architecture that triggers a saga when an EC2 instance changes state

EventBridge vs SNS vs SQS

Use EventBridge when:

• Routing events from AWS services (EC2, S3, CodePipeline, etc.)
• Content-based routing (match on nested JSON fields)
• Event replay required
• Schema registry and discovery needed

Event Pattern Matching

EventBridge rules use JSON patterns to match events:

{
  "source": ["com.myapp.orders"],
  "detail-type": ["OrderPlaced"],
  "detail": {
    "status": ["pending"],
    "amount": [{ "numeric": [">", 1000] }],
    "customer": {
      "tier": ["premium", "enterprise"]
    }
  }
}

Deeply nested content matching without any attribute tagging (unlike SNS). Supports: prefix, exists, anything-but, numeric ranges, IP prefix matching.

Targets

// Put events to EventBridge
eventbridge.put_events()
    .entries(PutEventsRequestEntry::builder()
        .event_bus_name("my-event-bus")
        .source("com.myapp.orders")
        .detail_type("OrderPlaced")
        .detail(serde_json::to_string(&order)?)
        .build())
    .send()
    .await?;

One rule can have up to 5 targets: SQS, Lambda, Step Functions, SNS, Kinesis, API Gateway, other event buses, etc.

Input transformer: reshape the event before sending to the target:

{ "orderId": "<$.detail.order_id>", "total": "<$.detail.total>" }

Event Replay

EventBridge archives can replay events from any point in time:

1. Create an archive: capture all events matching a pattern (or all)
2. On replay: specify time range → EventBridge re-delivers events to specified targets

Useful for:

• Rebuilding projections after a bug
• Re-running a failed downstream integration
• Testing new event consumers against real historical events

Key Takeaways

• EventBridge shines for event routing from AWS services and content-based filtering
• Patterns match on any JSON field — no attribute tagging required
• Event replay from archives enables re-processing without a separate event store
• Schema registry provides discovery and code generation for event types

Tomorrow: message ordering and exactly-once delivery with FIFO queues.