Services or capabilities described in Amazon Web Services documentation might vary by Region. To see the differences applicable to the China Regions, see Getting Started with Amazon Web Services in China (PDF).

Managing Amazon CloudFormation events using Amazon EventBridge

Amazon EventBridge is a serverless service that uses events to connect application components together, making it easier for you to build scalable event-driven applications. Event-driven architecture is a style of building loosely-coupled software systems that work together by emitting and responding to events. Events represent a change in a resource or environment.

As with many Amazon services, Amazon CloudFormation generates and sends events to the EventBridge default event bus. (The default event bus is automatically provisioned in every Amazon account.) An event bus is a router that receives events and delivers them to zero or more destinations, or targets. Rules you specify for the event bus evaluate events as they arrive. Each rule checks whether an event matches the rule's event pattern. If the event does match, the event bus sends the event to the specified target(s).

CloudFormation events

Amazon CloudFormation sends events to EventBridge whenever a create, update, delete, or drift-detection operation is performed on a stack. Amazon CloudFormation also sends events to EventBridge for status changes to stack sets and stack set instances. You can use EventBridge rules to route events to your defined targets. These events are guaranteed to be delivered, and they might be delivered out of order.

Since CloudFormation events represent changes to stacks or stack sets and their resources, you can use them to initiate workflows associated with respective events. For example:

The following events are generated by CloudFormation and sent to the default event bus in EventBridge. For more information, see Amazon CloudFormation events detail reference.

Sending Amazon CloudFormation events using EventBridge rules

To have the EventBridge default event bus send Amazon CloudFormation events to a target, you must create a rule that contains an event pattern that matches the data in the desired Amazon CloudFormation events.

Creating a rule consists of the following general steps:

For comprehensive instructions on creating event bus rules, see Creating rules that react to events in the EventBridge User Guide.

Creating event patterns for Amazon CloudFormation events

When Amazon CloudFormation delivers an event to the default event bus, EventBridge uses the event pattern defined for each rule to determine if the event should be delivered to the rule's target(s). An event pattern matches the data in the desired Amazon CloudFormation events. Each event pattern is a JSON object that contains:

For example, the following event pattern matches against all resource state change events:

{
  "source": ["aws.cloudformation"],
  "detail-type": ["CloudFormation Resource Status Change"]
}

While the following event pattern uses event detail data to match only resource state change events where CloudFormation creates a new AWS::S3::Bucket or AWS::SNS::Topic resource:

{
  "source": ["aws.cloudformation"],
  "detail-type": ["CloudFormation Resource Status Change"],
  "detail": {
    "status-details": {
      "status": ["CREATE_COMPLETE"]
    },
    "resource-type": ["AWS::S3::Bucket", "AWS::SNS::Topic"]
  }
}

For more information on writing event patterns, see Event patterns in the EventBridge User Guide.

Testing event patterns for Amazon CloudFormation events in EventBridge

You can use the EventBridge Sandbox to quickly define and test an event pattern, without having to complete the larger process of creating or editing a rule. Using the Sandbox, you can define an event pattern and use a sample event to confirm the pattern matches the desired events. EventBridge give you the option of creating a new rule using that event pattern, directly from the sandbox.

For more information, see Testing an event pattern using the EventBridge Sandbox in the EventBridge User Guide.

Amazon EventBridge permissions

Amazon CloudFormation doesn't require any additional permissions to deliver events to Amazon EventBridge. The events contain information which is already available through CloudFormation's API operations.

The targets you specify may need specific permissions or configuration. For more details on using specific services for targets, see Amazon EventBridge targets in the Amazon EventBridge User Guide.

Additional EventBridge resources

Refer to the following topics in the Amazon EventBridge User Guide for more information on how to use EventBridge to process and manage events.