Event structure reference

The following fields appear in all events delivered to an event bus, and comprise the event's metadata:

{
  "version": "0",
  "id": "UUID",
  "detail-type": "event name",
  "source": "event source",
  "account": "ARN",
  "time": "timestamp",
  "region": "region",
  "resources": [
    "ARN"
  ],
  "detail": {
    JSON object
  }
}

version

By default, this is set to 0 (zero) in all events.

id

A Version 4 UUID that's generated for every event. You can use id to trace events as they move through rules to targets.

detail-type

Identifies, in combination with the source field, the fields and values that appear in the detail field.

Events that are delivered by CloudTrail have AWS API Call via CloudTrail as the value for detail-type.

source

Identifies the service that generated the event. All events that come from AWS services begin with "aws." Customer-generated events can have any value here, as long as it doesn't begin with "aws." We recommend the use of Java package-name style reverse domain-name strings.

To find the correct value for source for an AWS service, see The condition keys table, select a service from the list, and look for the service prefix. For example, the source value for Amazon CloudFront is aws.cloudfront.

account

The 12-digit number identifying an AWS account.

time

The event timestamp, which can be specified by the service originating the event. If the event spans a time interval, the service can report the start time, so this value might be before the time the event is received.

region

Identifies the AWS Region where the event originated.

resources

A JSON array that contains ARNs that identify resources that are involved in the event. The service generating the event determines whether to include these ARNs. For example, Amazon EC2 instance state-changes include Amazon EC2 instance ARNs, Auto Scaling events include ARNs for both instances and Auto Scaling groups, but API calls with AWS CloudTrail do not include resource ARNs.

detail

A JSON object that contains information about the event. The service generating the event determines the content of this field. It can be "{}".

AWS API call events have detail objects with approximately 50 fields nested several levels deep.

Note

PutEvents accepts data in JSON format. For the JSON number (integer) data type, the constraints are: a minimum value of -9,223,372,036,854,775,808 and a maximum value of 9,223,372,036,854,775,807.

Example: Amazon EC2 instance state-change notification

The following event in Amazon EventBridge indicates an Amazon EC2 instance being terminated.

{
  "version": "0",
  "id": "6a7e8feb-b491-4cf7-a9f1-bf3703467718",
  "detail-type": "EC2 Instance State-change Notification",
  "source": "aws.ec2",
  "account": "111122223333",
  "time": "2017-12-22T18:43:48Z",
  "region": "us-west-1",
  "resources": [
    "arn:aws:ec2:us-west-1:123456789012:instance/i-1234567890abcdef0"
  ],
  "detail": {
    "instance-id": " i-1234567890abcdef0",
    "state": "terminated"
  }
}

Minimum information needed for a valid custom event

When you create custom events they must include the following fields:

• detail

• detail-type

• source

{
  "detail-type": "event name",
  "source": "event source",
  "detail": {
  }
}