AWS Lambda scheduled event source via cloudformation

Question

I already have my lambda / roles defined in cloudformation and would love to also use it to add a scheduled eventsources ... are there any docs or examples around ?

Answer 1

Use Aws::Event::Rule with a ScheduleExpression and a AWS::Lambda::Permission

// rule to periodically call the lambda
"TagWatcherRule": {
  "Type": "AWS::Events::Rule",
  "Properties": {
    "ScheduleExpression": "rate(10 minutes)",
    "Targets": [
      {
        "Id": "TagWatcherScheduler",
        "Arn": {
          "Fn::GetAtt": [
            "TagWatcherFunction",
            "Arn"
          ]
        }
      }
    ]
  }
},
// role may call the lambda
"InvokeLambdaPermission": {
  "Type": "AWS::Lambda::Permission",
  "Properties": {
    "FunctionName": {
      "Fn::GetAtt": [
        "TagWatcherFunction",
        "Arn"
      ]
    },
    "Action": "lambda:InvokeFunction",
    "Principal": "events.amazonaws.com",
    "SourceArn": {
      "Fn::GetAtt": [
        "TagWatcherRule",
        "Arn"
      ]
    }
  }
}

Answer 2

I solved same problem.

"RoleForLambdaStopEC2Instances" : {
  "Type": "AWS::IAM::Role",
  "Properties": {
    "AssumeRolePolicyDocument": {
      "Version": "2012-10-17",
      "Statement": [
        {
          "Sid": "",
          "Effect": "Allow",
          "Principal": {
            "Service": "lambda.amazonaws.com"
          },
          "Action": "sts:AssumeRole"
        }
      ]
    },
    "Policies": [
      {
        "PolicyName": "LambdaStopEC2InstancesPolicy",
        "PolicyDocument": {
          "Version": "2012-10-17",
          "Statement": [
            {
              "Effect": "Allow",
              "Action": [
                "logs:CreateLogGroup",
                "logs:CreateLogStream",
                "logs:PutLogEvents",
                "ec2:StopInstances"
              ],
              "Resource": [
                "arn:aws:logs:*:*:*",
                "arn:aws:ec2:*"
              ]
            }
          ]
        }
      }
    ],
    "Path": "/"
  }
},
"LambdaStopEC2Instances": {
  "Type": "AWS::Lambda::Function",
  "Properties": {
    "Code": {
      "S3Bucket": "XXXXXXXXXXXXXXXXX",
      "S3Key": "XXXXXXXXXXXXXXXXXX"
    },
    "Handler": "stopEC2Instances.handler",
    "Role": { "Fn::GetAtt" : ["RoleForLambdaStopEC2Instances", "Arn"] },
    "Runtime": "nodejs4.3",
    "Timeout": "5"
  }
},
"StopEC2InstancesRule": {
  "Type" : "AWS::Events::Rule",
  "Properties" : {
    "Name" : "StopEC2Instances",
    "ScheduleExpression" : "cron(0 13 ? * MON-FRI *)",
    "State": "ENABLED",
    "Targets": [{
      "Arn": { "Fn::GetAtt": ["LambdaStopEC2Instances", "Arn"] },
      "Id": "stopEC2Instances"
    }]
  }
},
"LambdaInvokePermission": {
  "Type": "AWS::Lambda::Permission",
  "Properties": {
    "FunctionName" : { "Fn::GetAtt" : ["LambdaStopEC2Instances", "Arn"] },
    "Action": "lambda:InvokeFunction",
    "Principal": "events.amazonaws.com",
    "SourceAccount": { "Ref" : "AWS::AccountId" },
    "SourceArn": { "Fn::GetAtt": ["StopEC2InstancesRule","Arn"] }
  }
}

Answer 3

The YAML Version

ScheduledRule: 
  Type: AWS::Events::Rule
  Properties: 
    Description: "ScheduledRule"
    ScheduleExpression: "rate(10 minutes)"
    State: "ENABLED"
    Targets: 
      - 
        Arn: 
          Fn::GetAtt: 
            - "LambdaFunction"
            - "Arn"
        Id: "TargetFunctionV1"
PermissionForEventsToInvokeLambda: 
  Type: AWS::Lambda::Permission
  Properties: 
    FunctionName: 
      Ref: "LambdaFunction"
    Action: "lambda:InvokeFunction"
    Principal: "events.amazonaws.com"
    SourceArn: 
      Fn::GetAtt: 
        - "ScheduledRule"
        - "Arn"

Answer 4

Unfortunately, configuring scheduled event sources for lambda functions is currently not supported by CloudFormation. You will need to deploy your lambda using CloudFormation and then manually configure your scheduled events.

CloudFormation does support an AWS::Lambda::EventSourceMapping resource type. However, this resource is limited configuring Kinesis or DynamoDB streams, so this is likely not helpful to you.

http://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-lambda-eventsourcemapping.html

---

**Update - as of April 2016, this is now supported using CloudWatch Events - https://aws.amazon.com/about-aws/whats-new/2016/04/amazon-cloudwatch-events-now-supported-in-aws-cloudformation-templates/

Answer 5

As of this week (18 April 2016) it is now possible to add a scheduled CloudWatch event rule that will trigger your Lambda function.

The AWS::Event::Rule has a ScheduleExpression field for the cron-style schedule and a Targets array which can accept a Lambda function ARN.

Answer 6

AWS supports periodic run through sourcedetails.

 EventSource: "aws.config"
 MaximumExecutionFrequency: Twelve_Hours
 MessageType: "ScheduledNotification"

Answer 7

If you use function name as

"FunctionName": {
      "Fn::GetAtt": [
        "TagWatcherFunction",
        "Arn"
      ]
    }

and you not specify the function then it'll throw you "Template is not valid: Template error: instance of Fn::GetAtt references undefined resource TagWatcherFunction"

So instead of function name you can directly specify the "lambda ARN". you can see example below

"TagWatcherRule": {
  "Type": "AWS::Events::Rule",
  "Properties": {
    "ScheduleExpression": "rate(10 minutes)",
    "Targets": [
      {
        "Id": "TagWatcherScheduler",
        "Arn": {
          "Fn::GetAtt": [
            "TagWatcherFunction",
            "Arn"
          ]
        }
      }
    ]
  }
},
// role may call the lambda
"InvokeLambdaPermission": {
  "Type": "AWS::Lambda::Permission",
  "Properties": {
    "FunctionName": "arn:aws:lambda:<region>:<awsid>:function:<lambd name>",
    "Action": "lambda:InvokeFunction",
    "Principal": "events.amazonaws.com",
    "SourceArn": {
      "Fn::GetAtt": [
        "TagWatcherRule",
        "Arn"
      ]
    }
  }
}