periodic sns alarm by itself (for cron-like lambda execution)

periodiic.json

{
  "AWSTemplateFormatVersion": "2010-09-09",
  "Parameters": {
    "period": {
      "Default": 3300,
      "Description": "SQS message lifetime. SNS events will be kicked every (300 + this value) seconds",
      "Type": "Number"
    }
  },
  "Resources": {
    "sqs": {
      "Type": "AWS::SQS::Queue",
      "Properties": {
        "MessageRetentionPeriod": {
          "Ref": "period"
        }
      }
    },
    "sqsPolicy": {
      "Type": "AWS::SQS::QueuePolicy",
      "Properties": {
        "Queues": [
          {
            "Ref": "sqs"
          }
        ],
        "PolicyDocument": {
          "Id": "QueuePolicy",
          "Version": "2012-10-17",
          "Statement": [
            {
              "Sid": "Allow-User-SendMessage",
              "Effect": "Allow",
              "Principal": "*",
              "Action": [
                "sqs:SendMessage"
              ],
              "Resource": "*",
              "Condition": {
                "ArnEquals": {
                  "aws:SourceArn": {
                    "Ref": "sns"
                  }
                }
              }
            }
          ]
        }
      }
    },
    "sns": {
      "Type": "AWS::SNS::Topic",
      "Properties": {
        "Subscription": [
          {
            "Endpoint": {
              "Fn::GetAtt": [
                "sqs",
                "Arn"
              ]
            },
            "Protocol": "sqs"
          }
        ]
      }
    },
    "alarm": {
      "Type": "AWS::CloudWatch::Alarm",
      "Properties": {
        "AlarmDescription": "Alarm if no message in queue",
        "Namespace": "AWS/SQS",
        "MetricName": "ApproximateNumberOfMessagesVisible",
        "Dimensions": [
          {
            "Name": "QueueName",
            "Value": {
              "Fn::GetAtt": [
                "sqs",
                "QueueName"
              ]
            }
          }
        ],
        "Statistic": "Minimum",
        "Period": "300",
        "EvaluationPeriods": "1",
        "Threshold": "0",
        "ComparisonOperator": "LessThanOrEqualToThreshold",
        "AlarmActions": [
          {
            "Ref": "sns"
          }
        ],
        "InsufficientDataActions": [
          {
            "Ref": "sns"
          }
        ]
      }
    }
  }
}