AWS EventBridge — What it is & Why you should learn it

What is AWS EventBridge?

AWS EventBridge is a serverless event bus that lets services and applications communicate via events instead of direct calls. It receives JSON events and forwards them to matching targets using rules you define.

Core building blocks

Event: A JSON record that describes something that happened (e.g., an S3 object upload).

Event Bus: The channel that receives events; AWS provides a default bus, and you can create custom ones.

Rule: A filter that matches events based on source, detail-type, and detail.

Target: The service that receives matching events, such as Lambda, Step Functions, SQS, or SNS.

Why learn EventBridge?

• Decoupling — Services publish events without knowing about consumers, enabling scalable architectures.
• Native integrations — Works with many AWS services and SaaS providers.
• Serverless & managed — No infrastructure to manage, with built-in retries and durability.
• Filtering — Match only the events you care about.
• Real-time pipelines — Process events as soon as they occur.

Typical use cases

• Data ingestion on S3 upload → Lambda → DynamoDB/Redshift.
• Microservices communication via custom buses and rules.
• Security and ops signals routed to responders.
• Cross-account event routing.
• SaaS integration (e.g., Zendesk ticket created triggers workflows).

Event pattern example (S3 → EventBridge)

This matches when a file is created under source/ in bucket batch89-etl:

{
  "source": ["aws.s3"],
  "detail-type": ["Object Created"],
  "detail": {
    "bucket": { "name": ["batch89-etl"] },
    "object": {
      "key": [ { "prefix": "source/" } ]
    }
  }
}

Tip: In EventBridge, multiple entries inside object.key are OR, not AND. If you need prefix AND suffix (e.g., source/*.csv), use S3 Notifications with prefix+suffix or filter in your code.