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Amazon EventBridge

Amazon EventBridge (formerly called CloudWatch Events) invokes your function asynchronously with an event document that wraps the event from its source.

Request

Example CloudWatch Event

EventBridge event example

EventBridge (CloudWatch Events) event example
{
   "version":"0",
   "id":"fe8d3c65-xmpl-c5c3-2c87-81584709a377",
   "detail-type":"RDS DB Instance Event",
   "source":"aws.rds",
   "account":"123456789012",
   "time":"2020-04-28T07:20:20Z",
   "region":"us-east-2",
   "resources":[
      "arn:aws:rds:us-east-2:123456789012:db:rdz6xmpliljlb1"
   ],
   "detail":{
      "EventCategories":[
         "backup"
      ],
      "SourceType":"DB_INSTANCE",
      "SourceArn":"arn:aws:rds:us-east-2:123456789012:db:rdz6xmpliljlb1",
      "Date":"2020-04-28T07:20:20.112Z",
      "Message":"Finished DB Instance backup",
      "SourceIdentifier":"rdz6xmpliljlb1"
   }
}

EventBridge scheduled event

EventBridge (CloudWatch Events) message event
{
   "version":"0",
   "account":"123456789012",
   "region":"us-east-2",
   "detail":{},
   "detail-type":"Scheduled Event",
   "source":"aws.events",
   "time":"2019-03-01T01:23:45Z",
   "id":"cdc73f9d-aea9-11e3-9d5a-835b769c0d9c",
   "resources":[
      "arn:aws:events:us-east-2:123456789012:rule/my-schedule"
   ]
}

EventBridge S3 event

EventBridge S3 event
{
   "version":"0",
   "id":"2d4eba74-fd51-3966-4bfa-b013c9da8ff1",
   "detail-type":"Object Created",
   "source":"aws.s3",
   "account":"123456789012",
   "time":"2021-11-13T00:00:59Z",
   "region":"us-east-1",
   "resources":[
      "arn:aws:s3:::jbarr-public"
   ],
   "detail":{
      "version":"0",
      "bucket":{
         "name":"jbarr-public"
      },
      "object":{
         "key":"eb_create_rule_mid_1.png",
         "size":99797,
         "etag":"7a72374e1238761aca7778318b363232",
         "version-id":"a7diKodKIlW3mHIvhGvVphz5N_ZcL3RG",
         "sequencer":"00618F003B7286F496"
      },
      "request-id":"4Z2S00BKW2P1AQK8",
      "requester":"348414629041",
      "source-ip-address":"72.21.198.68",
      "reason":"PutObject"
   }
}

EC2 Instance State-change Event

EventBridge (CloudWatch Events) invokes your Lambda function asynchronously with the event document from Amazon EC2.

Amazon EC2 State Change Events
{
    "version": "0",
    "id": "b6ba298a-7732-2226-xmpl-976312c1a050",
    "detail-type": "EC2 Instance State-change Notification",
    "source": "aws.ec2",
    "account": "123456798012",
    "time": "2019-10-02T17:59:30Z",
    "region": "us-east-2",
    "resources": [
        "arn:aws:ec2:us-east-2:123456798012:instance/i-0c314xmplcd5b8173"
    ],
    "detail": {
        "instance-id": "i-0c314xmplcd5b8173",
        "state": "running"
    }
}

CodeCommit Repository State Change

Merging changes
{
   "version": "0",
   "id": "01234567-EXAMPLE",
   "detail-type": "CodeCommit Repository State Change",
   "source": "aws.codecommit",
   "account": "123456789012",
   "time": "2019-06-12T10:23:43Z",
   "region": "us-east-2",
   "resources": [
     "arn:aws:codecommit:us-east-2:123456789012:MyDemoRepo"
   ],
   "detail": {
     "event": "referenceUpdated",
     "repositoryName": "MyDemoRepo",
     "repositoryId": "12345678-1234-5678-abcd-12345678abcd",
     "referenceType": "branch",
     "referenceName": "myBranch",
     "referenceFullName": "refs/heads/myBranch",
     "commitId": "7f0103fMERGE",
     "oldCommitId": "3e5983DESTINATION",
     "baseCommitId": "3e5a9bf1BASE",
     "sourceCommitId": "26a8f2SOURCE",
     "destinationCommitId": "3e5983DESTINATION",
     "mergeOption": "THREE_WAY_MERGE",
     "conflictDetailsLevel": "LINE_LEVEL",
     "conflictResolutionStrategy": "AUTOMERGE"
   }
}

Getting the correlation id

JSON path to correlation id: id

Generating sample events

sam local generate-event cloudwatch scheduled-event

Response

N/A

Resources

Typing and data classes

Handlers with infrastructure provisioning

Code Examples

DotNet has a large number of handlers for CloudWatch Events.

DotNet ECSTaskStateChangeEvent example
public class Function
{
    public string Handler(ECSTaskStateChangeEvent ecsTaskStateChangeEvent)
    {
        Console.WriteLine($"ECS Task ARN - {ecsTaskStateChangeEvent.Detail.TaskArn}");
    }
}

Jet - CloudWatch Rules Events allows you to define the infracture code next to the implementation

Ruby example might be getting notified when an unwanted security group port gets opened.
class SecurityJob < ApplicationJob
  rule_event(
    description: "Checks for security group changes",
    detail_type: ["AWS API Call via CloudTrail"],
    detail: {
      event_source: ["ec2.amazonaws.com"],
      event_name: [
        "AuthorizeSecurityGroupIngress",
        "AuthorizeSecurityGroupEgress",
        "RevokeSecurityGroupIngress",
        "RevokeSecurityGroupEgress",
        "CreateSecurityGroup",
        "DeleteSecurityGroup"
      ]
    }
  )
  def detect_security_group_changes
    puts "event: #{JSON.dump(event)}" # event is available
    # your logic
  end
end
Chalice can also to the infrastructure provisioning along set the Lambda handler

Example using Chalice to subscribe to code commit events
app = chalice.Chalice(app_name='foo')

@app.on_cw_event({"source": ["aws.codecommit"]})
def on_code_commit_changes(event):
    print(event.to_dict())
Chalice scheduling ab hourly Cloudwatch event
app = chalice.Chalice(app_name='foo')

@app.schedule('rate(1 hour)')
def every_hour(event):
    print(event.to_dict())

Documentation


Last update: 2022-06-20