CloudWatch Event

CloudWatch Events (now part of Amazon EventBridge) deliver a near real-time stream of system events that describe changes in AWS resources. osls can wire a cloudwatchEvent rule to a Lambda function so that the function runs whenever a matching event occurs. For new projects, consider the eventBridge event source instead.

Simple event definition

This will enable your Lambda function to be called by an EC2 event rule. Please check the page of Event Types for CloudWatch Events.

functions:
  myCloudWatch:
    handler: myCloudWatch.handler
    events:
      - cloudwatchEvent:
          event:
            source:
              - 'aws.ec2'
            detail-type:
              - 'EC2 Instance State-change Notification'
            detail:
              state:
                - pending

Enabling / Disabling

Note: cloudwatchEvent events are enabled by default.

This will create and attach a disabled cloudwatchEvent event for the myCloudWatch function.

functions:
  myCloudWatch:
    handler: myCloudWatch.handler
    events:
      - cloudwatchEvent:
          event:
            source:
              - 'aws.ec2'
            detail-type:
              - 'EC2 Instance State-change Notification'
            detail:
              state:
                - pending
          enabled: false

Specify Input or Inputpath

You can specify input values ​​to the Lambda function.

functions:
  myCloudWatch:
    handler: myCloudWatch.handler
    events:
      - cloudwatchEvent:
          event:
            source:
              - 'aws.ec2'
            detail-type:
              - 'EC2 Instance State-change Notification'
            detail:
              state:
                - pending
          input:
            key1: value1
            key2: value2
            stageParams:
              stage: dev
      - cloudwatchEvent:
          event:
            source:
              - 'aws.ec2'
            detail-type:
              - 'EC2 Instance State-change Notification'
            detail:
              state:
                - pending
          inputPath: '$.stageVariables'
      - cloudwatchEvent:
          event:
            source:
              - 'aws.ec2'
            detail-type:
              - 'EC2 Instance State-change Notification'
            detail:
              state:
                - pending
          inputTransformer:
            inputPathsMap:
              eventTime: '$.time'
            inputTemplate: '{"time": <eventTime>, "key1": "value1"}'

Specifying a Description

You can also specify a CloudWatch Event description.

functions:
  myCloudWatch:
    handler: myCloudWatch.handler
    events:
      - cloudwatchEvent:
          description: 'CloudWatch Event triggered on EC2 Instance pending state'
          event:
            source:
              - 'aws.ec2'
            detail-type:
              - 'EC2 Instance State-change Notification'
            detail:
              state:
                - pending

Specifying a Name

You can also specify a CloudWatch Event name. Keep in mind that the name must begin with a letter; contain only ASCII letters, digits, and hyphens; and not end with a hyphen or contain two consecutive hyphens. More information here.

functions:
  myCloudWatch:
    handler: myCloudWatch.handler
    events:
      - cloudwatchEvent:
          name: 'my-cloudwatch-event-name'
          event:
            source:
              - 'aws.ec2'
            detail-type:
              - 'EC2 Instance State-change Notification'
            detail:
              state:
                - pending

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